Schematic Diagrams and Service Manuals

Electronics Repair Manuals

This website allows you to find the repair manuals for any electronic devices that you could think of. You will also be able to access schematic diagrams and other useful materials for repairing electronics. You will be able to find the documents that you need to repair your TV, your DVD and VCR players, your mobile phones and cameras, and computer monitors, plus more! You will even be able to find the diagrams and repair guides for very old devices, so you don't have to worry if you think that the guide is out of print; chances are that this site will have it! You don't need to freak out now when your TV breaks down; you will be able to find the guide to repair it and have it working again in no time! Most of the guides come in easily downloadable PDF files, so you can read them on your computer, phone, or tablet! Read more...

Electronics Repair Manuals Summary


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High Performance DTMF Decoder Simplifies Control of Remote Base Stations

Dtmf Remote Control Pic

Refer to the schematic diagram in Fig 1. The design centers around two LSI CMOS integrated circuits, the American Microsystems S3525A band-split filter and the Mostek MK5102 DTMF decoder. Together, these devices contain an incredible amount of circuitry which permit building a highperformance DTMF decoder with a minimum of parts. A color burst TV crystal controls all of the digital timing functions therefore, no critical, interactive adjustments are required.

An easily built project for interfacing with most transceivers

Figure 1 shows the schematic diagram lor the Simple Simplex Repeater Point J1 is the input ol the carrier-operated squelch (COS) signal from the radio. A received audio signal is said to be present when the COS signal is greater than 0.7 V. switching the collector of transistor Q2 to ground. The play record UV R) pin of Ul. the ISD1000A, then becomes low, placing U1 in record mode. NAND gates U3B and U3C are set up as inverters, and thus generate a high output. D flip-flop 1-4A is clocked on this positive edge, therefore making the Q output high. NAND gale U3A has hoth inputs high, therefore generating a low input to the power down (P )) pin of Ul. The resistor R2 and capacitor C6 combination is used to generate a brief delay.

An Introduction To Amateur Fivi

Heath Ib101

Fig. 3, IB-101 schematic diagram. The schematic diagram of Fig. 3 shows what the IB-101 is made of. The input amplifier and Schmitt trigger circuits accept and shape the input signal into a square wave. Decade counters change these sequential input pulses into a binary coded 8-4-2-1 output and recycle on every tenth input pulse. The four bits of binary coded information are then connected to the buffer storage units which accept and store the count data on command of the transfer signal. The decoder drivers translate the binary coded information from the buffer storage units into decimal form and drive the proper display tube cathodes. Timing signals for gating, transfer, and reset are generated in the clock and divider chain. It's all quite neat, you'll have to admit.

Tube Heterodyne Receiver Circuit

Tube Auto Radio

W1R 0 AN APPARATUS ON MOTOR'BOtAS , ' V 11 SCHEMATIC DIAGRAM, Fig. 25. Schematic diagram of a 5 tube radio-phonograph receiver. (Emerson Model CJ-221.) Voltage rating 105 125 volts power consumption 30 watts and 20 watts for the 78 r.p.m. phonograph motor. The frequency range is from 540 to 1,780 k.c. SCHEMATIC DIAGRAM SCHEMATIC DIAGRAM Fig. 31. Schematic diagram of an eight-tube frequency modulation, radio receiver and converter. (Stromberg-Carlson No. 425.) This receiver is designed for the reception of frequency modulated broadcasting stations only, and features the popular Armstrong wide-swing frequency modulation system, making possible virtual static and noise free reception, which in addition to extreme high fidelity makes it an outstanding radio development. At present the Federal Communications Commission has established five channels between 40 and 44 megacycles for frequency modulated transmitting stations. Since this is a comparatively high frequency, the distance over...

Time Domain Reflectometry In Ohm Systems

The adapters are 25-ohm resistors with connectors which are compatible with the -hp- TDR system and with common 75-ohm systems. Fig. 2 is a schematic diagram of a typical TDR setup for testing a 75-ohm cable. Energy returning to the TDR system from the cable is properly terminated in 75 ohms by the series combination of the 25-ohm adapter and the 50-ohm TDR system. There is no source mismatch to cause re-reflections.

Amateur Speech Amplifier Utilizing The Tc Speech Filter

The circuit shown in the schematic diagram comprises an effective amateur speech amplifier and river unit due to the excellent voltage regulation of the oilput signal. This desirable driver characteristic has been obtained by using a 6AS7G twin triode tube which possesses a very low AC plate to plate resistance. This tube is capable of supplying a clean 10 watts of audio power which is adequate for driving any of the popular Class B modulator tubes having output ratings up to 500 watts. The voltage gain of the unit is quite adequate for high impedance dynamic or crystal microphones. The circuit wiring is simple and straight-forward. The manner in which the chassis ground and the B minus return circuits are connected will have a large bearing on making the low level stages hum-free. Precautions to observe are as follows Insulate the electrolytic filter and decoupling condenser cans and also the microphone input connector from the metal chassis. The B minus circuit wiring should be...

Clough Brengle Model 210 Rf Signal Generetor

Planta Puerta Levadiza

The schematic diagram of the Clough-Brengle Model OM frequency modulated r-f. oscillator. The 76 tube in the middle of the diagram is the constant frequency oscillator that is frequency modulated by the motor driven condenser at the left. Fig. 279. Schematic diagram of the Egert Model VRO oscillograph. Fig. 279. Schematic diagram of the Egert Model VRO oscillograph. Figs. 288, left, 289, middle, 290, right. Schematic diagrams showing two types of demodulator circuits with three types of load circuits. The correct points for connecting to the deflection plates are indicated by V. The results obtained when connections are made to other points are explained in the text. Figs. 288, left, 289, middle, 290, right. Schematic diagrams showing two types of demodulator circuits with three types of load circuits. The correct points for connecting to the deflection plates are indicated by V. The results obtained when connections are made to other points are explained in the text.

Oscilloscope Preamplifier

The op amp schematic diagram looks like a triangle. (See Figure 1). There are two input terminals used to correctly address input signal information to the op amp. They are traditionally drawn on the left-hand side of the schematic symbol as represented in Figure 1. Figure 2. Schematic diagram of the oscilloscope preamplifier using an SK90I7 integrated circuit, Note ihat he fC pins are numbered differently for the Texas Instrument's ME592.)

Variable Dc Supply Employing Thyratron Rectifiers

C. power supply shown in the schematic diagram finds its main application in amateur phone and CW transmitters and in laboratories where a variable source of D. C. voltage is frequently desired. This circuit does not require the usual primary variac or a voltage dropping resistor to obtain control of the output voltage. Three high voltage D. C. Power supplies have been designed employing grid controlled rectifiers. One unit employs type FG-17 thyratrons and will deliver a maximum output of 1500 volts D. C. at .5 amps. The second power supply utilizes type 627 thyratrons and is capable of a maximum D. C. output voltage of 2500 volts at .5 amps. The third design employs R. C. A. type 2050 thyratrons and has a maximum output voltage of 400 volts D. C. at . 2 amps. The various circuit values and transformer types required for each individual supply are listed directly below the schematic diagram.

Audio Amp And Spkr Driver

Tuned Collector Oscillator Model Graph

These receivers are commonly supplied with a schematic diagram. In a typical model (most of them are about the same avoid reflex circuits) the first transistor serves as a common-emitter mixer and a collector-feedback tunable local oscillator The next two transistors are if amplifiers at the usual near-455 kHz frequency. There is even an AGO circuit A diode detector provides the AGO cor if rol voltage and the audio to a one-transistor gain stage. A trails former-coupled two transistor push-pull audio output stage, which may include a thermistor for compensation of temperature effects, feeds the small loudspeaker. A small phone jack may be wired to disconnect the loudspeaker when using the low-impedance earphone. 1 e usual arrangement is shown in block-diagram form in

For Further Information

The receive side is somewhat more involved. The desired bandpass characteristic for using the Bell 202 tones is not met very well by unmodified amateur or commercial FM communications equipment. While a demodulator can be made to work by limiting and careful adjustment it has been shown that the XR2211 PLL demodulator used in the TAPR TNC yields a performance improvement on the order of 3 dB when preceded by the switched capacitor fiiter shown in the schematic diagram.

The Neat m Amplifier

C5 is adjusted to peak the input circuit at the base of Ql and C6 peaks the output at QTs collector. L4 through L8 on the schematic diagram are striplnies designed into the circuit board itself. The amplifier may easily be modified for Class C operation, if desired. Fig. I. Schematic diagram* The Ten-Tec manual contains a troubleshooting guide that you probably won't need, but it's there, just in case. Its 26 pages include a circuit description and schematic diagram. Ten-Tec also has a limited warranty and a phone number for technical assistance should you need it. The back cover of the manual shows the resistor color codes and bits of other useful

Parametric Amplifiers

How can an electronics technician who's right out of the service or a tech school go directly into research and development work Jf you think your training might qualify you for a job as an electronics technician, check into it. It's a good deal. The pay is competitive, and the working conditions and fringe benefits are tops* (Experience Isn't necessary, but if you've been on the ob for up to two years, the deal is even better.)

Electrolytic Capacitor Testing At Cycles

Capacitor Testing Bridge Schematic

As indicated in the accompanying schematic diagram, the 120-cycle measuring voltage is applied in series with the external d-c polarizing voltage normally required for electrolytic capacitor testing. Since the d-c supply is grounded, the test voltage must be supplied through an isolation transformer, which can also serve to match the low impedance of the bridge (from a few ohms to a few thousand ohms) to the 120-cycle source.

For Electrolytic With The Capacit Bridge

Tance Test Bridge has been available for some time.1 The modification as shown in the schematic diagram (Figure 2), consists primarily of the addition of terminals for connection of an external generator and of providing 120-cycle tuning for the internal detector. Switching is provided so that either the standard circuit or the special configuration can be used.

Two New Transformers for Measurements on Balanced Systems

Audio Bridging Transformer

A schematic diagram of the 5 kc to 600 kc transformer is shown in Tig, 3. The switch shown in the diagram is built into the transformer ease at are the resistances in the secondary circuit. The transformer is designed for use with either 135- or 600-ohm systems and can be made to have an input impedance of 135, Fig, J. Schematic diagram of -hp- AC-60A. Fig, J. Schematic diagram of -hp- AC-60A.

Air Force Receiver BC

Some of the symbols in the schematic diagram on page 81 are obsolete. However, they will still be found in some technical orders. The symbols that do not correspond with symbols elsewhere in this manual include those for tubes, fixed and variable capacitors, and permeability-tuned coils.

Electrical Communications Technique And Its Applications In Allied Fields

The Wien bridge circuit has been chosen for the Type 434-B Audio-Fre-quency Meter because it eliminates both of these objections. Since it uses only resistance and capacitance, it has no external magnetic field. The two variable resistors may be so constructed that the frequency scale has the most desirable shape. A schematic diagram is shown in Figure 1. The conditions for balance of this bridge are

The Amplifier And Null Indicator

The schematic diagram, Figure 2, shows the connections of the detector circuit. The sensitivity potentiometer controls the gain of the amplifier and hence controls the sensitivity of the visual indicator. This sensitivity control is extremely useful when the full sensitivity of the bridge is not desired or when the bridge is being used as a limit indicator.

Miller Wide Band

Parts placement is not particularly critical, as long as the input and output arc well separated. It may be laid out basically, as the schematic diagram (see Figure I) is drawn with a ground bus around the perimeter of the board, R6 is an optional Ik-gain control that may either be placed in parallel with, or used instead of, fixed resistor R2 to allow for variable gain output. You can also reduce the preamp's gain by inserting an appropriate input or output fixed resistive pad.

FETs as Variable Resistors

Fig. 7 is a schematic diagram of the electronic attenuator. Two pairs of field-effect transistors are the variable resistors. The bias voltage (E in Figs. 5 and 6) is quite low 20 mV so the FET's operate in the linear regions of their V-I characteristics, and therefore look like resistors. The resistance of each branch varies from about 30 Q to 1 MQ.

See The Space Shuttle Video

See the above article in the June ' 2 issue of 73, page 10. Although the PC board toil pattern and the parts placement diagram are correct as shown, the schematic diagram (Figure T) has Ihree errors Ttie +RFT and the -RPT lines are reversed in the schematic and the value of the capacitor attached to Ihe Vcc fead on the bottom EPROM should be changed trom a 0.1 xf value to 10 jiF In ackJilion, Ihe program to detemiine the EPROM frequency select dala is missing ihe divide by symbols in lines 70 and 90, Also, the values in lines 100, 110 and 120 have been changed in the new versron. See the figure tor the correct program. This pro

High Frequency Circuit Design

The latest FCC Extra class study outline lists items like preselector design and the use of Smith charts. Your favorite amateur references may have a paragraph or two on these topics, but High Frequency Circuit Design has many pages. If you are looking for a schematic diagram for a high-powered amplifier, you will be disappointed, but if you are genuinely interested in what makes an ri amplifier work, this book just might hold the answer.

Specifications And Schematics Available Free On Request

Radiofrequency Diathermy Diagram

The amateur who will search out this equipment can acquire a good selection of heavy duty power supply components at little or no cost. Also, the configuration of many diathermy machines is ideally suited to amateur construction. The schematic diagram of a Burdick Corporation device, a fairly typical unit, is shown in Figure 1. Plug-in assemblies are used to provide output on 3.75, 12 and 50 megacycles to meet various treatment and surgical requirements. The rf components used in most equipments will have little attraction for the amateur primary interest lies in the power supply and possibly the enclosure. Fig. J Schematic diagram of a typical diathermy unit. This equipment was manufactured by Surdick Corporation and provided output on 3,75, 13 and 50 MC. Fig. J Schematic diagram of a typical diathermy unit. This equipment was manufactured by Surdick Corporation and provided output on 3,75, 13 and 50 MC.

Automatic Scanner System

Simplified schematic diagram showing connections for guarded scanning of two-terminal components. Figure 2. Simplified schematic diagram showing connections for guarded scanning of two-terminal components. Figure 3. Simplified schematic diagram of scanner switching circuit. Figure 5. Simplified schematic diagram showing interconnections between control unit and switch unit. Figure 5. Simplified schematic diagram showing interconnections between control unit and switch unit. Figure 5 shows a simplified schematic diagram of some of the interconnections between the Scanner Control Unit and the Scanner Switch Unit. Two decade counters in the Scanner Control Unit determine the active channel by means of the matrix ( crosspoint ) connection shown. For example, if the tens decade is set to 0 and the units decade to 9, tens-driver transistor TO and units-driver transistor U9 will be

Analysis Of The Superheterodyne

To get an overall view of a typical superheterodyne receiver, examine the complete schematic diagram on page 38. Two special purpose tubes are used. The pentagrid converter functions as local oscillator and mixer. The variable tuned circuits are ganged for oscillator tracking. Trimmer capacitors CI and C2 and padder capacitor C3 are included to help in tracking. They are screwdriver

Circle Oh Reader Service Card

Refer to the above article in the December 1992 issue, page 12. Diode D1 is backwards in the schematic diagram Figure 3), it should be Installed as shown in Figure 1 below. Note that the diode position is shown correctly in the parts placement diagram in Figure 4b. TNX to Joe Leikhim for the correction.

Deluxe Function Generate

A function generator is one piece of equipment found in the Jab of nearly every electronics technician and engineer. In conjunction with an oscilloscope, a function generator can be used to test or trou-blesboot most gear found in the hamshackn Unfortunately, commercial funaion generators are priced well out of the range of most hams, and good used ones don't often appear at hamfesis, Consequently, I decided to design my own I iis simple, low-cost function generator features TTU square-wavcT

Ghz Data Sheet Available

The 8 page data sheet provides complete ratings and electrical characteristics, package dimensions and representative power curves for each device. The data sheet also presents an extensive amount of applications information for circuit designers, including a discussion of metallization and reliability, input and output matching networks, and blocking and bypass capacitor selection. Schematic diagrams and parts lists are given for circuits used to derive performance data.

Lowpass Series Moerjved Tsection

Fig, 8, Differences between constant-k'1 and m-derived filters are apparent when the schematic diagrams are examined. Any *'m-derivedtf filter contains resonant circuits replacing simple reactances, f'Series'1 and shunt portions of names refer to type of resonant circuit, either series-resonant or parallel (shunt).

Circle On Header Service Card

Enjoy toll-free ordering and technical assistance. Over 21.000 electronic repair parts and components. Orders shipped within 24 hours hom two locations. The best catalog v ith easy reference index and hundreds of new products each issue. The best repair electronics value going

To Oscillator Screen Supply

hanging around1' this fantastic learning spot, being educated in the true tradition of electronic repair. I was one jf the lucky ones, for I received the kind of electronic education that no school can ever hope to offer. I was taught little tricks of the trade thai have benefited me in later life the type of education or which I will be eternally grateful

Alignment Of Tuned Circuits

Schematic diagram of a motor driven frequency modulator con' nected to an oscillator. The oscillator is tuned to the mean frequency of the circuit under test and the motor driven condenser varies the output frequency over a predetermined band, say 10 kc. each side of the mean frequency. Fig. 251. Schematic diagram of a motor driven frequency modulator con' nected to an oscillator. The oscillator is tuned to the mean frequency of the circuit under test and the motor driven condenser varies the output frequency over a predetermined band, say 10 kc. each side of the mean frequency.

Circle S M Re Ao Er Service Card

1990 Ham Radios

In the schematic diagram in Figure I IC I, a 400IB quad NOR gate operates as a monostable multivibrator, or one shof The first pulse, applied to pin 6. fires the one-shot (with R2 and C2 providing the time constant) that remains triggered for the duration of the burst. The result is a single puise of se eral milliseconds, suitable for triggering IC2.

Power Supplies for the Stimulus Response System

Fig. 2 shows the schematic diagram of the starting circuit block shown in Fig. 1, A 1000- tF capacitor is charged via the resistive divider until the potential across it reaches 26V, At this point, Z24 becomes conductive and switches on the drive circuit for the transistor switch. Energy is then fed to the control circuit. When the potential across the capacitor has decayed to 12 V, the transistor switch is turned off and the circuit is ready to begin a new cycle. If no fault condition is sensed by the control circuit, the power supply begins operation before the end of the first start cycle. If. on the other hand, a fault is detected, the start cycle is repeated at three-second intervals. After the start cycle, all primary Fig. 2. Starting circuit schematic diagram Fig. 2. Starting circuit schematic diagram

Call Direct Use Area Code

The parts listed on the schematic diagram are the ones I used because they happened to be available in the junk box. However, the value of the components used are not too critical, and can easily be substituted if not available, or example, potentiometer R1 mav be of any value from about 250 ohms to about 2500 ohms, I just happened to have a 500 ohm pot, so that's what I used, R2, R3, R4, and R5 may be of values from 100k ohms up to 500k ohms, and too, each one can be of a different value within this range as they are all used individually and have no interaction in the circuit. However, 1 would not use a pot lower than 100k ohms because of possible damage to the meter, and I would not use one higher than 500k ohms because the higher value makes the tuning too critical. The capacitor CI need not necessarily be a .005 but should be something close to this value at 1000 wvdc or higher. The diode D1 could be a 1N48, 1N60, 1N64, 1N6G, or some other type and work equally well Since I had a...

Benchtop Inductively Coupled Plasma Mass Spectrometer

The schematic diagram of an ICP-MS instrument is shown in Fig. 1. Basically, liquid samples are introduced by a peristaltic pump to the nebulizer where a sample aerosol is formed. A double-pass spray chamber ensures that a consistent aerosol is introduced to the plasma. Argon (Ar) gas is introduced through a series of concentric quartz tubes, known as the ICP torch. The torch is located in the center of an RF coil, through which 27.12-MHz RF energv is passed. The intense RF field causes collisions between the Ar atoms, generating a high-energy plasma. The sample aerosol is instantaneously decomposed in the plasma (plasma temperature1 is in the order of 6,000 to 10,00OK) to form analyte atoms, which are simultaneously ionized. The ions produced are extracted from I he plasma into I he mass spectrometer region, which Solid Sample Analysis. Solutions and liquids are the normal sample types measured by ICP-MS. Solid samples are normally digested using mineral acids and analyzed as...

Around a glass cylinder

Do not feel that there is any real need for such Lissajous figures during routine frequency calibration. With careful operation with ratios up to 10-1, complete coverage can be had with a high degree of accuracy. However, we show the schematic diagram and several examples for those who may want to develop such patterns. To establish the fre-

Simple Multiuse Amplified Speaker

Fig. 1 is the schematic diagram of this amplified speaker. S) is a SPOT toggle switch with a center-off position (on-none-on). In one position it connects the internal 9-Volt battery to power the amplifier. In the opposite position it connects the amplifier to J3, to which is connected an external storage batter or regulated power supply. When the unit is not in use. the switch is centered,

Power Line Disturbances and Their Effect on Computer Design and Performance by

Although they are meant for different applications and represent different design approaches, both of these new power supply families take advantage of a new HP switching transistor called a power MOSFET (metal-oxide-semiconductor field-effect transistor) MOSFETs have been around for a while and their superiority over other kinds of transistors for many high-frequency applications is well known. However, until recently there weren't any with the HP device s combination of high voltage rating, fast switching speed, low resistance, high reliability, and small chip size. The cover photograph shows where the HP power MOSFET fits in the schematic diagram of a 65000A Power Supply. On page 18 is an article about the new MOSFET, telling why it's different and how it's made.

An Enhancement Mode PHEMTfor Single Supply Power Amplifiers

Schematic diagram of the MBE layer structure of the enhancement-mode PHEMT. operation, bettergm linearity than a conventional DFET. The HP Laboratories' approach employs molecular beam expil axy (MBE) to place a highly doped, thin electron donor layer close to the gate, with the electron donors on hoth sides of the Ino.2Gao.sAs channel. Highly selective reactive ion etching is used to define the vertical position of the Schottky gate. Figure 1 is a schematic diagram of the MBE layer struct ure of the enhancement mode PHEMT.1

To the center of the trace the receiver tuning can be changed and the

Cathode Ray Tube Diagram

Schematic diagram of the Supreme Model 555 oscillograph. The functioning of the frequency modulator is explained on the opposite page. On the right is the front view of the Hickok Model RFO-1 Oscillograph. The schematic diagram of this instrument will be found on the next page. In the revised model the spot positioning controls, as well as all the others, are on the front panel. Schematic diagram of the Hickok Model RFO-1 cathode-ray oscillograph. Schematic diagram of the Hickok Model RFO-1 cathode-ray oscillograph. Schematic diagram of the Triumph Model 800 cathode-ray oscillograph. Note the two rectifiers, the type 879 supplying the high voltages for the cathode-ray tube, type 906, and the type 80 supplying the bias and plate voltages for the remainder of the tubes. Schematic diagram of the Triumph Model 800 cathode-ray oscillograph. Note the two rectifiers, the type 879 supplying the high voltages for the cathode-ray tube, type 906, and the type 80 supplying the bias and plate...

Millimeter Wave Source Module Interface

Fitting the digital circuitry Into the module was another design constraint. A 4-bit-wide bidirectional data bus was chosen as the best compromise between precious printed circuit board space within the module and minimal pin use on the interface connector. Fig 1 shows a schematic diagram of the circuitry resident in the module. Data slored permanently in ihe nonvolatile RAM (NOVRAM) s read by first loading each counter (U2 and U3) with the desired memory address and then enabling the NOVRAM data output Using a s mlliar procedure, permanent programming of the memory is allowed when test points A and B are jumpered together. While this approach burdens the driving instrument's firmware design, it simplifies the hardware required in the module The module's complete digital interface requires only eight connections and five small ICs.

Digital Combinatorial Triggering

A major Logic Analyzer design consideration was that all controls be simple to use and intuitively understood by digital users. The trigger section is a good example. All trigger switches are grouped in a shaded area on the front panel (Fig. 3). The algorithm describing trigger requirements is drawn on the front panel as a simple schematic diagram using common digital symbols.

Operational Analysis Of A Simple Radio Receiver

To analyze the simple radio receiver, study the schematic diagram shown on page 6. In this schematic, are gathered together all the steps just discussed. The points to be considered in the analysis are What are the essential components What are the functions of each component - What are the changes made in the radio waves as they pass through the receiver

Relative RF Power Meter

Fig. 1 shows the schematic diagram for the Relative RF Power Meter. J1 is the RF input. J2 is the connector for the 50-ohm terminator. The RF signal enters at JI. is rectified by D3. and filtered by FB1 and FB2, and charges Cl. RU, RIO, and R3 form a voltage divider which determines the meter's sensitivity to input power. Overvollage protection of Ul's input is provided by

Feedback effects in an amplifier will be examined in some detail in

The basic equivalent circuit of the tetrode is essentially that of the triode, even though a screen grid exists in the tetrode. A schematic diagram of a simple amplifier circuit employing a tetrode is given in Fig. 4-6. In drawing the equivalent circuit, the rules given in Sec. 3-3 have been appropriately extended and

The application of positive feedback has the opposite effects Thug

The principle of feedback is illustrated in the schematic diagram of Fig. 5-16. For simplicity, series injection is shown at the input, but other forms of network coupling may be employed. In the diagram shown, a voltage Eg is applied to the input terminals of the amplifier, with the polarity as shown. Suppose that the resultant voltage at the output terminals is Epk. Suppose that a fraction 3 of this output is fed back in series with the input signal in such a way that the resultant signal that appears between the grid-cathode terminals has the form

Tuned Power Amplifiers

The basic circuit of a tuned power amplifier is substantially that of the single-tuned direct-coupled type discussed in Sec. 10-1. The essential differences are in the magnitude of the grid-bias supply voltage Ecc, the corresponding value of the grid input signal eg, and the amount of power involved. A schematic diagram of a tuned power amplifier is given in Fig. 11-1. Fig. 11-1. Schematic diagram of a tuned power amplifier. Fig. 11-1. Schematic diagram of a tuned power amplifier.

Special Combination Offer

The amplifier shown in Figure 1 can work well over the frequency range of 10 to 50 MHZ. The 40673 dual-gate MOBFET is capable of higher frequency operation however, there are belter devices today for Ihose applications. If you want to build this circuit it will work however, il is primarily used for component selection examples. With the schematic diagram (Figure 1) in mind, let's go shopping for parts. Don't

Dual Output Laser Module for a Tunable Laser Source

The laser module must maintain precise alignment between the laser diode and two collimating lenses and provide electrical connections for the laser chip drive current and the laser temperature controller. We have provided this functionality in a small, robust and hermetic package (Fig. 2). A schematic diagram of the laser module is shown in Fig. 3, A semiconductor laser chip with one facet antirefleetion-coated is solder-mounted to a submount and heat sink. The heat sink is temperature-controlled with a Peltier cooler using a thermistor to monitor the temperature. The reduced temperature extends the laser life and increases the optical output power for a given laser current. In addition, by minimizing temperature fluctuations, thermally induced refractive index changes in the chip are reduced. This improves the wavelength stability of the external-cavity laser. Fig. 1. .Schematic diagram of a wavelength-tunable external cavity laser containing a hermetic laser module. Fig. 1....

Frequency In Cycles Per Second

Base and sound-level meter without cable correction. Figure 3 is an elementary schematic diagram of the system. As is indicated, no external grid-leak is used to determine the bias for the preamplifier. The insulating material supporting the back plate structure of the microphone is a glass-bonded mica with a leakage resistance of more than 107 megohms and is specially treated to remove and seal out moisture. So long as the leakage resistance is maintained at this high value, the grid bias is established by the voltage gradient within the electron cloud surrounding the cathode. Under these conditions it has been found that the bias is stable and the noise level over the 20-kilocycle band at the output of the preamplifier is approximately 20 a volts or low enough so that sound levels of 40 db (re 0.0002 ubar) can be meas

Bookbind THIS Conclusion

This is the third and final part of this series. The previous two described the tools, materials, and fixtures required for the processes involved. The objective behind the process is to save valuable technical information that has been placed into your hands. Most all of the technical knowledge shared with us is in the form of a schematic diagram, which, if saved, will continue to share the knowledge forever.

Adj For Freo While Counting

Fig. 1-3, Schematic diagram shows basic circuit as used in a continuous-ione-squelch repeater access system. Parts values shown are not applicable to single-tone encoder applications (see text). Figure 1-3 is the schematic diagram for the unit, which is essentially a phase-shift oscillator coupled into an emitter follower. Since the power consumption of the oscillator circuit is so low, a standard 9V transistor-radio battery will provide an ideal power source. At full output, the oscillator draws no more than about 3 mA.


The Symbols chapter includes a listing of the upper and lower-case characters of the Greek alphabet. There is also an extensive table of electronics schematic-diagram symbols. It is hard to imagine that I will ever need to perform a unit conversion that isn't covered somewhere in the 25 pages of conversion factors. There is a two-page temperature conversion table that I found especially interesting. Read a known value in bold type on this chart. The value to the left is the Celsius equivalent of a Fahrenheit value or the one to the right is the Fahrenheit equivalent of a Celsius temperature. It is a very easy to use chart, with values given for every degree from 0 to 100, and every ten degrees down to -100 and up to 500. (This means the table covers a range between -148 and 932 F or -73.3 to 260 C.)


Esquema Inversor Essab Plus Todos

Figure 2 shows the schematic diagram of the amplifier portion of the system (AM-494 GR). The unit comes equipped with a pair of 4CX150A tetrodes, the same lineup Johnson used in its Thunderbolt kilowatt unit. These are extremely rugged tubes and are capable of comfortably running a full thousand watts input by themselves. The big secret is keeping the bottles cool which is no problem with this amplifier because an efficient air-blowing system is built right in. Construction of the tube sockets is such that the cooling air circulates from the tube bases up past the ceramic envelopes to


The quality objective implied that the counters had to carry the standard HP warranty of one year on parts and labor. To achieve this objective, it was necessary to assure that when a counter did require repair, servicing could be accomplished easily, rapidly, and at low cost. As a result, the service engineer was involved during the initial design states. His early involvement meant not only that the instrument would be easily serviced but that the operating and service manual would help keep both the need for servicing and the attendant costs to a minimum. The service engineer made many recommendations for lest points and for redesigning the printed-circuit boards to make the test points easier to find and more accessible. In the manual, test points are emphasized on schematic diagrams, and waveforms and truth tables are incorporated into the schematics. The manual contains information for users not familiar with common electronic equipment for example, explanations of BNC...

Etron Rf Notes

Volume 1 is a new software package from Etron Enterprises which aids in the design of Butterworth-response filters to the seventh order. Based on network modeling, the program designs low-pass, high-pass, bandpass, and band-reject filters as a function ot input output impedance ratios and user-defined input parameters, The output of the program is a schematic diagram labeled with circuit constants,

General Description

The ACT-40 Amateur Transmitter is housed in ACT-40-C black-crackle finish cabinet rack having overall dimensions of 19 inches wide, 15 inches deep, 26 inches high. The weight of the transmitter is approximately 164 pounds. A schematic diagram of the complete transmitter is shown in Figure 19.

Cowect To

Integrated Circuit Agc

Schematic diagram of the RCA OA Fig- 2. Schematic diagram And photograph of the Motorola MC 1550, Terminal numbers refer to leads on TO-5 type package. Fig- 2. Schematic diagram And photograph of the Motorola MC 1550, Terminal numbers refer to leads on TO-5 type package. The schematic diagram for the RCA CA

Vernier Dial

This oscillator has been a very worthwhile replacement for the old tube model in the station transmitter. As mentioned, the output was adequate to drive my rig, but some transmitters in the Novice class might require a little more drive. The output level is dependent on supply voltage increasing the battery to 12 or 1 SV will provide additional drive. However, the supply should not be much over 20V unless a 2N697 is used at Q4 in place of the 2N706 shown on the schematic diagram. Different bias resistors for Q5 as well as a larger dropping resistor for the zener diode would be required if the supply is increased. An untuned vacuum tube buffer amplifier might be more effective to couple into an existing transmitter if the output of Q5 is not enough alone. . . .W9ZTK

Grid Dip Meter

Grid Dip Meter Circuit

Study of the schematic diagram w*ill disclose nothing really new in circuitry, although the AM modulation capability is an additional and very useful feature not found in many other instruments. The circuit is a conventional ultra-audion oscillator using a split stator tuning capacitor, A inilliameter is connected in the grid circuit and the plate voltage is made adjustable to control the magnitude of oscillation. This permits setting the grid current to the optimum point on the meter scale. When the grid dip meter coil is coupled to a circuit tuned to the oscillator frequency, it will absorb power, This loss of energy results in a decrease in the magnitude of osc l-lation and is indicated by a reduction in grid current. Therefore, by tuning the instrument for a dip on the meter and reading the frequency from the dial, the resonant frequency of the externa circuit is quickly determined.

Heard On The Band

There are stilt two active operators on Johnston Island. KH3AA, the chief electronics technician for the installation there, is on generally once a week, and IKJ6BJ can often be found around 14056 kHz from 0600Z. WH3AAA is reported to also be on the island and trying to upgrade. The New Jersey DX Club has

New Books

In addition to the question answer sections, the book goes into detail on learning code, the requirements for each class of license, details on how to fill out the form 610, and the examination schedule for the various FCC offices. There is also a chapter devoted to the schematic diagrams needed for the exams.


As an electronics technician, I'm always on the lookout for test gear for the workbench or shack When my forly-year-old audio signal generator finally bit the dust, I decided it was lime for a new piece of gear to take its place Luckily. I found exactly what was looking for m a friend's Dick Smith Electronics catalog ihe K-3520 function generator kit it was inexpensive ( 69.95), attractive, and had pretty decent specs.


1990 Ham Radios

In this age of high tech watches, LCD speedometers, and pagers-in-a-pen, it was only a matter of time until some of that new technology filtered down to the lowly electronics technician. The most common high tech test tool lately is the digital multimeter probe. . . . it was oniy a matter of time until some of that new technology filtered down to the lowly electronics technician

Wide Impedance Range

The secret of this unusual instrument is the variable-ratio transformer shown in the accompanying schematic diagram. This transformer must be a good approach to an ideal transformer. It must respond over a frequency range of 20 to 10,000 cycles per second, and it must he so constructed that the losses are as nearly constant as possible for every one of the ratio adjustments. A compensation network operated by the ratio changing switch corrects for small differences, so that for all ordinary purposes the transformer has a constant loss. The instrument always presents a nearly resistive impedance to an external circuit.

Dual Tone Control

Thordarson's development of this Dual Tone Control was prompted by the many requests of sound men for an effective tone compensating system to boost or attenuate the bass or treble frequencies independently of each other. Examination of the schematic diagram will show that the final circuit is simple and not at all complicated to construct. It is constructed on a small chassis, making it adaptable to practically any existing amplifier.

Is Homebrew OM

Every year, in thousands of new hamshacks, this scene ensues. The Novice sends away to all the QSL printers that advertise in 73, QST, the Callbook and Popular Electronics. Then, amid samples of stock, print styles, cartoons, illustrations and doo-dads, the new ham sends away for the card that expresses his personality ,.,96 point callsign, as in the WA6XXX card, superimposed on the schematic-diagram background, as in the WA5XXX card, with overside fill-in data as in the ZD 10AA card. The January '62 issue of 73 had a good article on making QSL s for club members. The idea was that all the members could chip in to pay for an artist's design which would then go on all ol their cards, this approach is fine if you don't mind carbon copy cards and belong to a club. If not, it's not.


You can see the setup for an alignment procedure in the schematic diagram on page 167 for a superheterodyne receiver. Note that the tuning indicator is an output meter connected across the secondary of the output transformer. A signal generator (shown in three different positions) provides a test signal which, in turn, provides an output indication. Each stage is tuned for a maximum indication on the output meter.


Schematic diagram of the preamplifier. Numbered components are identified below. Fixed-value resistors are carbon composition, 1 4 W. Fixed-value capacitors are disc ceramic, 50 WV. Numbers in parentheses identify Radio Shack numbers. C7 through C6-5-60-pF miniature trimmer (272-1340) Q1 -MRF901 (276-2044) Q2 2N3819 (276-2035)

From Turnon

Schematics For Carryall 272

Schematic diagram of the input circuits. Switching at only three points converts a conventional Schmitt circuit, used with external drive, into a wide-range oscillator for internal prf control. Figure 6. Schematic diagram of the input circuits. Switching at only three points converts a conventional Schmitt circuit, used with external drive, into a wide-range oscillator for internal prf control.

Bookbind THIS Part

Hams, above most others, communicate technical information via schematic diagrams. Schematic diagrams carry the concept of a project design and techniques for achieving a useful piece of equipment. Unless the various issues are cataloged and stored where they can be found, the valuable information is essential v lost forever

Vhf Frequency

Two months ago we started describing our frequency counter design, showed how to use it and gave a complete parts list. i his month we will provide the complete logic and schematic diagrams, and describe how it works, and next month we will have the printed circuit board layout, parts layout drawings, and construction and operation information.

Circuit Section

The schematic diagrams given on the following pages have been carefully chosen to illustrate the use of different generic tube types in diversified transmitting applications. All of the circuits are designed to give reliable and satisfactory performance they show, for the most part, simple, conventional, straight-forward arrangements which experience has shown to be dependable. Although relatively few circuits are given, it is often practical to use a portion of one circuit in combination with portions of other circuits to obtain a design meeting the desired requirements. In general, almost any circuit shown using a triode, tetrode, or pentode tube type is equally suitable for any other tube type in the same generic group, provided the necessary revisions are made to meet the ratings of the tube used.


HAM- I V, a complete tvM k on the subject which gives all the fundamentals plus full instructions on putting a station on the air for under I By W KYQ. 3.00 ATV BULLETIN. Published bimonthly for all amateurs Interested in Ham-TV, Issue 4 now out. Lists all active TV stations, newest circuits, and other chitchat. 1.0(1 per year MILITARY SURPLUS TELEVISION EQUIPMENT by W4WKM, Photos, description ami schematic diagrams of the most popular surplus TV equipment CRV-f AAK television camera, the CRV-53AAG camera. CRV-52ABW Television Transmitter, CRV SOABK Television monitor, CRV-46ACD Television Receiver. These re units of the ATK Television equipment.

Unstable Signature

An intermittent fault is one of the biggest problems in electronic repair. The fault comes and goes, and in most cases does not stay long enough for positive detection. Signature analysis can detect such faults if they occur within a measurement window. However, the operator may not receive the message if the measurement cycle time is too short.


The audio test panels as constructed are shown in the schematic diagram of Figure 2. A Hartley oscillator delivers voltages at each of five selected frequencies (40, 100, 400, 2.500, and 6500 cycles) covering the audio-fre-quency band. At each of these fre- Figure 1. Schematic diagram of the test panel for making rapid measurements of gain and overload


As many readers concluded* the dual iok potentiometer is non-standard and, therefore, must be replaced with another value for the speed control in the free-running multivibrator. One solution which provides a two-fold advantage is to use a dual 10k potentiometer. First, a standard control is provided. Secondly, the small amount of fixed resistance w hich is placed in series with each potentiometer prevents the maximum speed from exceeding 50 WPM. Hence, the elusive 5,8K, i watt resistors which appeared in the photographs, now have a logical place in the schematic diagram.


One of the features of this unit is that it can be used with three different meters (i.e., multimeter, plate current meter, or ratiometer). Operation of the unit is quite simple. Referring to the schematic diagram (Fig, 2), it will be noted that zener diode CRT holds the voltage of battery B1 at 3.9 volts I his is applied to a series resistance network so that the voltage drop from the lower end of control R14 to the junction of R13 and R22 is approximately 40

Network Qslcards

Before applying power to the transmitter, you should make a thorough visual inspection. Check for solder bridges, poor solder connections* melted wire insulation and component leads touching other con-doctors. Double-check all connections to make sure they agree with the schematic diagram.


As shown in the elementary schematic diagram of Figure 2, the Type 1390-A Random-Noise Generator uses a gas-discharge tube as the noise source. A transverse magnetic field is applied to the tube in order to increase the noise level at high frequencies and to eliminate the oscillatory nature of the electrical discharge usually obtained in a gas tube.1 The noise output from this gas tube is amplified in a two-stage amplifier. Between the first and second stages the noise spectrum is shaped in three different ways, depending on the setting of the range-switch control shown just below the meter in Figure 1. At the 20-lcc setting, a low-pass filter is inserted, which has a gradual roll-off above 30 kc, with the audio range to 20 kc uniform in spectrum level. The 500-kc setting puts in a low-pass filter that rolls off above 500 kc. At the 5-Mc setting, a

By Melanie M Daniels

Fig. 2 is a photograph of the power module. Tire schematic diagram, Fig. -3, shows the electrical design of the power module. The bias circuits must be simple and fast because of the pulsed nature oft be GSM modulation. Because of the Fig. 2 is a photograph of the power module. Tire schematic diagram, Fig. -3, shows the electrical design of the power module. The bias circuits must be simple and fast because of the pulsed nature oft be GSM modulation. Because of the

Construction Notes

Figure 4 is ihe transmitter s schematic diagram, When buili as a transceiver, a DPDT switch lakes care of the transmit receive switching. 1 put this switch on the rear of rig up high where it's easy to reach. One half of the sw itch is used for switching the antenna to the receiver and transmitter. The other half sw itches 12 volts to the receiver iiain control line during receive, and supplier 2 volts to the transmitter during transmit.

July Vol Viino

Schematic diagram of the Type 516-A Radio-Frequency Bridge. The heavy lines represent the bridge element , the light line the shields Figure 3. Schematic diagram of the Type 516-A Radio-Frequency Bridge. The heavy lines represent the bridge element , the light line the shields

Second Tuning Unit

Block Schematic Network Analyzer

A simplified schematic diagram of one of the tuning units is shown in Figure 14. The circuit is basically a two-stage tube-and-transistor amplifier. There is negative feedback from the collector circuit of Q-l to the filament of Y-l, which stabilizes the gain of the amplifier and the operating points of V-l and Q-2. There are two possible paths for positive feedback. One of these is the so-called Wien bridge network, which produces a maximum feedback at one frequency and gives the tuning unit its selective characteristic. The other is a resistive voltage divider, which gives the tuning unit its flat frequency or all-pass characteristic. When either positive feedback network is used, there is always an excess of negative feedback for stability of gain.

Send For Free

The schematic diagram of the regulated supply used in the I iA 109 chassis is shown in Fig. I. Both the rectifier filament and the high voltage secondary windings of the transformer are regulated. The inductance of I he high voltage secondary winding is tuned to resonance by the 2 mfd capacitor. Because of this resonant condition, a high circulating current flows in the winding, causing this section of the core to become saturated. Because of Ibis saturation, the secondary voltage is relatively constant over a wide range of load and primary voltage variations.

Of Operation

The input signal is clipped or limited, amplified, clipped a second time, and amplified again. The resulting wave-shape approximates a square wave or a series of pulses, depending upon whether the input signal is a sine wave or pulses, respectively.

Meter Station

ARC-1 Xav Surplus Transmitter Receiver Xmtr. u cs 832A in final, 20 waits input, with AM push-pull plate modulation. Ten crystal controlled channels. rcq range 100-3 Me, Receiver lias extra, separate guard channel which can be tuned for your net frequency. Complete with tubes, schematic diagram, and conversion instructions for AC power supply and tunable oscillator. Shipping wt. GU pounds, t'scd good. 524.95


The programmer uses these symbols to draw a schematic diagram of the tasks to be done to accomplish an end task. This schematic is then used as his reference to complete the programming. Fig. 12. Flowcharting symbols. The programmer uses these symbols to draw a schematic diagram of the tasks to be done to accomplish an end task. This schematic is then used as his reference to complete the programming.

Div Of

The pan adaptor power supply is designed for 38011000 cycles. It will be necessary to replace the power transformer with a 60 cycle oscilloscope power trans former. The one used by the author was a replacement transformer for a Heath 0-11 oscilloscope. See modified schematic diagram. Most transformers do not provide for a 1B3 filament winding. The transformer used in this conversion used a IV3 high voltage rectifier, The author also wished to remove the power connector, name tag, fuse liolder, handle and mounting fasteners from the front panel to give the unit a commercial appearance. Step 1. Replace power transformer with 60 cycle version. Remove 400 cycle transformer. See schematic diagram for transformer details. lie author, in order to mount the transformer he had available, cut a hole in the chassis and mounted the transformer on two small angle brackets.

Circuit Description

Sra Robinson

Figure 0 is a simplified schematic diagram of the converter. Twelve input lines (4 for each decade) connect the electronic switches S1-S12 to the flip-flops in the counter's storage decades. The nominal input voltages are +65 v for a binary 1 and +185 v for a binary 0. For a decade in state 9 (decimal) all four flip-flops are in binary state 1 (+65) and for decimal 0 all flip-flops are in binary state 0 (+185). Each of the electronic switches, S1-S12, connects the associated output resistor (weighting re

S Io Frequency

A schematic diagram of how pseudo-Rayleigh noise can be produced from two GR 1 382 Random-Noise Generators 1 is shown in Figure 6. High-conductance germanium diodes, such as 1N455 or 1N695, should be used for low forward voltage drop. A dc amplifier will be needed if it is necessary to reduce the output impedance level or to provide more power.

Voltage Test

If all connections are found to be correct, the tubes may be inserted and the line-cord plug connected to a 110-volt 60-cycle receptacle and the speaker (1500- to 2000-ohm field) plugged in A slight turn of the Tone-Control knob to the right will turn on the receiver. After a brief warm-up period the voltages shown on the Schematic Diagram should be checked with a high-resistance voltniultr, u available. Voltages indicated are , measured from the point shown, to the chassis, with the' chassis as the negative terminal. If values measured are materially different than shown on the diagram, a thorough recheck of the circuit should be made. Be sure the receiver Is turned off and the linc-eord disconnected from the power receptacle while the wiring is being becked.


Schematic diagram oj the converter. All resistors are hU+watt carbon. All bypass capacitors arc disk ceramic, Dipped silver mica capacitors arc preferred for capacitance values below 100 but disk ceramics arc acceptable unless otherwise specified. The 1 pL dipped silver mica capacitors are made by Cornell Dubilier. For best sensitivity* connect the 77588 source directly to a ground lug as at A. For better overload control, connect the 1 V191 (or IA'192) diodes across 1 as at CX, and then connect the 77S88 source to the 330 ohm (,005 in -) bias network as at B.

Delayline Oscillator

A novel use for a variable delay line is illustrated in the schematic diagram of Figure 1. The circuit utilizes the delay line as the feed-back element of a triode oscillator. The delay line may be thought of as a phase-shift network having 180 phase shift at a frequency corresponding to twice the delay time and its odd harmonics.


F1 0.5 amp line fuse T - J J 5 VAC primary, 20 V-flC secondary at 0.5A DJ j 8V I W zener D2tD3 smalt diode combinations D4 -D7 400V 1A rectifier diodes Rs series current setting resistor SI - AC 3 pole, 5 positioj rotary switch M - 0 30V voltmeter Q1 GE-14 transistor Q2 40466 transistor.

Book Review

European systems are prominent in this book because the author is with the Department of Electrical and Electronics Engineering at the University of Wales, Swansea, UK. This means that metric units are used throughout, and the Queen's English may occasionally confuse us colonials. Nonetheless, the book has a wide range. It describes cellular systems and techniques used in the US, UK, Scandinavia and Japan. A two-page appendix briefly describes systems in many countries. Contributors include Hewlett-Packard Company, Marconi Instruments Ltd and Rohde & Schwartz UK Ltd.

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