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- - fundamentals

Most of the articles dealing with integrated circuits (ICs) either explain the theory of internal electronic operation or show some complex use for the device to someone who is already familiar with ICs.

It is not necessary to have an understanding of how they work to begin using and enjoy working with ICs. What is needed is the nuts and bolts practical information on how to get started usually overlooked by the more advanced technical article.

The 1C can be basically ihuughi of as a miniaturized primed circuit (PC) board, It is a complete electronic circuit within its package, built to perform some specific function.

This is both the problem and the key to easily working with them. Instead of working with components and building a circuit with them, you are working with the complete circuit as a plug-in unit adapted to your purpose.

The cheapest and most obtainable 1C surplus available Is the digital type, This was designed for computer use. Amateurs use it two basic ways: as it was designed when they can use that particulai 1C function, and by externally manipulating it to perform some unrelated function that it was never designed for.

Many counters use digital ICs to count the same way a computer would. Other equipment takes the com puter circuit and makes it work as an amplifier, product detector, oscillator, and so forth .

This article will try to answer some of the more obvious questions about how to start working with digital ICs and get usabie results. The first question is:

How Do I Tell What These Devices Are?

An IC is named for the particular computer function it performs in a digital computer. Most of the time the name will not be of any value to the amateur, except to identify the device to be used. He will he using il in a different way for a different purpose liian it was intended.

It also has a code number, as tubes and transistors do. There are a I ¡mi Led number of

chi;

specific computer functions, but a variety of ways they may be packaged.

An IC package may contain only one actual circuit, or it may have a number of them inside. This is for computer building convenience. It may seem confusing at first that so many code numbers seem to he :he same circuit, but they may be different combinations within the package.

An IC also belongs Lo a "logic family/' This heading is usually given over the list of code numbers in the ads. This refers to the electronic means by which the circuit does its work.

The circuit function can be performed a number of ways electronically. While this is important for com* puter use, it is less so for amateur use. When you become more experienced, the need to become more selective about which logic family you use may arise — but not when you are starting out.

Where Do I Get More Specific Information?

Check the ads and send foi the catalogs of surplus IC dealers. This will give you at least one number/name cross reference that you might need.

When you order, for a slight additional charge you can get the data sheets for the devices you order. If you plan to do a lot of work with ICs, there are several data books available on the common K families (for about three dollars each).

Careful reading of IC articles will also give you quite a bit of information. One article may not give it all, but comparing several will yield something you can use.

With So Much To Choose From, What Do I Start With?

The important thing is to begin. Keep it simple. Some particular devices are standing out as most commonly used.

The family lo start with is the TTL (transistor transistor logic) family, also referred to as T^L. These are cheap, rugged and available.

Within this family there are two devices which are well known and eas> to work with. They arc the 7400 quadruple dual input NAND gate and the 7490 decade counter. Forget the names and look foi the numbers. You may just see H'7400 gate" and "7490 counter' hi the ad.

What Can I Do With Them?

The 7400 is the heart of many IC oscillator circuits, and is often adapted to perform other common circuit functions. This is one area where ihe device is adapted to perform tasks \\ was not designed for.

The 7490 likes to divide by \\y.ot five and ten. It s^ the heart of many dividing and counting circuits. This is a case of the device being used as it was designed.

One obvious use would be to combine the two and make a multiple output frequency standard such as 100 kHzT 10 kHz, 5 kHz or a custom output for a particular use.

By learning with the simple circuit you gel the practical basics of the more complex dividing chains used in counters or other exotic gear.

These are basic circuits, The 7400 has also been adapted to perform many of the functions of a complete SSB generator, acting as oscillator, mixer, buffer and so forth. This makes it a good device with which to learn the basics of external circuit manipulation.

What Else Will I Need To Get Started?

Besides a i:ew ICs to play with, you will also need a few biisic ítems to start off with. These should be thought of as capita I investments. You will use them over and over again as you work.

You will need a power supply. For digital ICs you need 5 V dc, preferably regulated. This is no problem and will be dealt with later.

You wül need one of the IC breadboard matrices. For experimental circuits, ihere is no more practical way of working with them. Printed circuit board techniques are clumsy and don't lend themselves to quick changes. Individual sockets and components are much too fussy to work with conveniently,

You wilt also need a supply of small parts to use with the ICs, There arc fewer used with an IC circuit than with tubes <>r transistors, and with careful buying they are much cheaper.

What Is It Going To Cost To Get Started?

I lie initial investment will be in the neighborhood of thirty-five to forty dollars, most of which is for nonexpendable items used over and over again.

This compares favorably with what you would spend on a comparable breadboard setup for tubes or transistors if you started from scratch.

After the initial investment, the cosi per circuit will be lower than with tubes. Careful planning of purchases and buying ahead at quantity prices can bring the cost way down.

The biggest expense will be the IC breadboard matrix. The Pro to Board 100 at $19.95 (plus postage) or the AP Superstripat $17,00 (plus postage) is probably the best investment.

Plenty of ready*built supplies, kits, and Individual parts to build supplies are available surplus for between five and ten dollars.

As for the rest, five to ten dollars will buy a good supply of 7400s and 7490s, and a fistful of the small pans you will need to build a loi of the basic circuits.

The initial high cost will also be offset by the fact lhat, with the use of the breadboard matrix, you will be abie to use the small parts over and over again without cutting the leads.

After the initial investment, the cosi per additional experimental circuit will be much less than with tubes.

What Kind OI Power Supply Will J Need?

Digital ICs want 5 volts dc, preferably regulated. This is not hard to arrive at. It is much easier ihan with lube supplies.

While a complex piece of IC equipment might draw several Amps, for an experimental supply anything from 200 mA to an Amp will be satisfactory. Even a battery will run several ICs.

Linear ICs work from a wider range o voltages, usually in the 9-IS volt class, and there are some types of ICs (like differential ampii-iieis) which take two voltages one plus, one minus — in thai range. This sounds harder to do than it is, but start with the digital IC and the single supply.

What About Voltage Regulation?

Here is where you really get a break with ICs. A well regulated dc tube supply is quite an undertaking. With ICs, it's a breeze.

If you have a transistortype bench supply in the 9-1 2 volt range, just add an IC regulator such as the LM309H ($.75 to $1.50, depending on the source) and

When you are ordering parts, include a few regulators and some disc capacitors. They are quite cheap.

Where Does The Power Go?

Many partial schematics are ambiguous about some of the IC connections. As with tube circuits that don't show the trlamem circuit, assuming that you know where it goes, the IC circuits use a form of shorthand.

Most ICs have a pin connection for the source voltage (Vcc) and a ground return for the other feg of the voltage. Many times this is just not shown.

With a multisection IC, there is still just the one Vcc input which feeds all the sections.

Fig, 2, your supply problem solved.

These come in a variety of packages which look like familiar transistor types. Thc\ have three leads: one input, one output, and one ground. CarVt get much simpler than that. They will handle about one Amp each.

What About Additional Filtering?

It is best to regulate the voltage right at the IC unit, which makes the IC regulators ideal. If the power supply is at a distance from the unit, it is best to bypass the input with .1 uF or more.

It is also advisable to bypass each IC package uith .01 to .1 uF, to prevent interaction between ICs* This may not be needed experimentally and not all finished circuits will need or have it.

How Do I Read The Schematic?

Reading IC schematics is easy once you know how. Two systems are used. The first is to use the actual computer circuit function schematic symbol. This is often used when a multisection IC is broken up to perform several functions.

The important thing to remember is that the computer symbol is only used for convenience andl usually has no computer meaning in the circuit.

I he numbers on the pins refer to the pin numbers of the complete IC package. An example is shown in Figt I, which is one section of the 7400 with the pin numbers shown. The other Ihree sections would be drawn the same way, with the correct pin numbers foi cai h.

Often the entire IC is shown as a rectangle with the pin numbers on it, making it look like a largi: rectangular tube socket. The important thing here is that, unlike tube sockets, the IC pins are counted from the top of the case. Pin one is usually located by a mark.

Since most ICs are used with printed circuit boards, most of the other parts are top mounted; thus, the pins are shown from the top of the device.

Fig, 2 shows the complete 7400 IC package with the four sections drawn inside and the pins numbered. Also shown are the Vcc pin, common pin, and the associated bypass and voltage regulator^ for basic recognition o( ihe complete unit.

Can I Use My Junk Box Parts With ICs?

For outboard things like power supplies, switches, chassis, and chassis mounted parts, you probably can. For the pans directly connected to the IC, it is unlikely. They will be too big to fit conveniently and the leads may be loo thick to use with the IC matrix without damage.

Considering the low cost of miniature surplus IC components and the convenience of using them, this is no problem. Use what you can of what you have. The tittle parts are cheap.

Where Do 1 Find Circuits?

Basic individual circuits are now common in most of the magazines. The larger articles may have what you need as part ol another device which you might not want all of.

Can I Adapt Circuits From Other Pieces Of Equipment?

Very often you can. Unlike tubes, tCs are designed to be building blocks. The ICs in a family are designed to interface with each other.

Often it is possible to isolate the IC and its external circuit components that you want, and use it in another project without serious modifications.

How Are IC Circuits Coupled?

The two most common methods of coupling are direct coupling, where one output pin of an IC goes directly to the input pin of the next IC, and capacitor coupling. This makes it very simple most of the lime.

Whai About Unused Leads Or Sections?

There is no hard and fast rule. Many ICs have such high ^ain ihat a floating input pin or section can cause insia-bit ity problems. There are several ways of dealing with this.

One of the safest general methods is to return all unused input leads to the \ cc pin through a 1000 Ohm resistor. It is noi necessary to use separate resistors for each lead. All leads from the IC cati be returned through the same resistor.

Look at similar IC schematics. Sometimes the lead will be left floating or will be grounded. With grounding, some ICs will drau too much current. A miliiammeter in the Vcc line will show you what the current is doing.

Transistors Are Easily Damaged; What About ICs?

ICs are quite rugged. Manv problems are simplified because the^ are matched to be interconnected. The most critical voltage is the Vcc voltage. There is a \ en small range above and below this in which ICs v\<II work properh without damage. Using the small IC regulators will take care of this.

The next thing to watch is that they aren't over driven. If you are using ICs with each other, this is unlikely, but il you are using an external drive voltage it may cause damage the vime as overdriving a transistor,

DonT let that scare \ou. It i> not too common. They are quite rugged compared to transistors and they are vir\ cheap. Ai 20(1 or less for a 7400, you can blow out quite a few learning and never feel it.

What About Using Other ICs?

The 7400 and the 7490 were chosen here because they arc commonly used and information is readily available. There are plenty of others which can be used.

The basic oscillator circuit uses two gale sections. There are other computer gates which will also work. If you happen to have a stray IC gate type which is not a 7400, try it in the same type of circuit. It may work and il won't hurt to try.

Check through the IC anicies and keep a file of the types of ICs used. The ne\t most commonly used will show up that way.

What About Linear Devices?

Once you have gotten past the IC hurdle and have worked a bit with the digital type, you can begin to expand. As the prices come down, it becomes attractive to try the linear devices.

The regulator ICs you will be using arc linear devices. The others which you might be interested in are the types that perform some radio or other desirable amateur function without the need for external fudging* They are

IC SHOPPING LIST Power Supply

S volt regulated or 9-12 volt tranststor type

9 voli transistor radio type ban ety

Matruc

Proioboard 100 $19.50 i postage}

Prot aboard 6 $15,95 postage)

IC Types

TTL digital 7400 series 7400 gaie, 7490 counter Linear LM309H, K or equtv. 5 volt regulator

Capacitors

Resistors

1/4 Wan carbon. Most used values for ICs listed: 150, 220, 330,470, 560, 680, Ik, 1.8k, 2.2k {Available in sets quite cheaply with moie values an set)

Hookup Wire

^22 or smdller solid

(Add other items needed for specific projects desired, in order to make up minimum orde* requirements, or get price breiik on quantity ordered.)

internally designed lei perform thai specific task.

One of the simplest and most available, directly applicable 10 many uses, would be the audio type IC These range from duai stereo preamps to complete p re-amp/power amp ICs that are well within the range ol what is used in communications work.

Working up from thai, there are iht- ICs designed for commercial use which are complete i-f strips or com-

KlDNAPPTD: Drake TR 22 with crystals for 34^94, 94-94, 16 76, 04-64, 64 64, 38 receive. Texas D/L no, 4472525 on chassis. Jack Van-Nana WB5DYE, Tulsa OK, Phone (9181 627 3738.

ABDUCTED: Regency HR2A s/n 04 10422, Crystalled for 94,94 34 94. 16 76. 52. 52. Has bracket attached and cigarette lighter plug on power cord. Stolen from Don Billjngs W0GOH, 2838 N. Prospect St., Colorado Springs CO 80907. phone 303 636 166 K

plete subsections of communications type receivers. Some are specialized for FM or TV.

As these find their way into common amateur use, they ma\ well put the design of simple but effective equipment back in the range of something which can be done with limited means.

Many of them will work with the IC matrix and a standard Iransist or-type supply. (5 volts is rather lean for the linear devices.) There are some that will not fit into

FILCHED: Motorola two freqh( control head, Motorola T-power mike, Moto. speaker, 16 button TT pad with light, mounted in Bud Sox. Stolen from Jim Best WA0RZ1, 1923 Alpine Drive, Colorado Springs CO 80907, phone 303 47M486.

HIJACKED Regency Hft28, sn ur known. Crystalled for 34.94, 34 34. 16 76. 19 79, 22 82, 28. 88, 88 8G. 145.80/30 68, 58 25 85. Stolen from Glenda Butkr WBOOCH. 1509 E. 12th St.F Pueblo CO 81001, phone 303-544-7777

the standard IC matrix, being designed for direct PC board use.

The thing to look for is the standard DIP 'Dual Inline Package) configuration. Most of the ads will tell you if it is an unusual construction. Many of the audio power types have heat sink tabs. You can still use them, but not as easity as using the matrix.

What Am I Waiting For?

I don't know. What have

STOLEN: Atlas 210X xcvr sn TH3214 with Lafayette mobile mike modified with 3 conductor V diam plug. Does not have dc power cord or ac supply. Also Lafayette HA 146 2 mtr kcvt s/n 111T with mike, power cord and the following xtajs: 52-52, 16-76, 76 76, 19 79, 22-82, 34-94, 94-94, and 147 69 09. If any info call collect (213) 374 8528. Les Goddard WB6URL, 2121 Clark Lane, Redondo Beach CA 90278.

PLUNDERED: EBC i44Jr„ s/n 50108, synthesized rig, Stoten from Dick Sucher WA02LY, 27 Learning Road, Colorado Springs CO 80906, phone 303-47 M696.

LOOTED: Kenwood TS520 s/n 140579 engraved WA7WDC, and an icom 230 a n 24-05651 also engravec WA7WDC. In addition about S7,000 worth of tools and test equipment. If anyone has any information to the recovery of the this equipment please notify the Phoenix City Police, G, M. Chinn WA7WDC, 906 E, Broadway, Phoenix AZ 85040.

ROBBED: Genave GTX 200, s/n 22-03, ss number inside 031 28 9354. Crystalled for 157.63 03, 147.06, 156,37-97, 34 94. 9*94 and MARS frequency. BNC on back: for duplex operation. Extra relay inside for sw. mike and motor control head; early vintage set. Stolen from Gus McKinney W30GFR, 807 Holmes Drive, Colorado Spring CO 80909 phone 303-473-?397.

HIJACKED- Regency HR-2P s/n 04-02604 with mead battery pack attached, s/n 7157; with microphone. Rig had modifications for Topeka preamp and extra 6 channel crystal deck. Stolen from my car parked at Ramada inn, 1900 Fort Myer Drive, Arlington, Virginia, night of ^flarch 31. 1976. If you have any information on this equipment, please contact A. D. Abercrombie W2GJS, 1002 iMerrymount N , Turnersvilie NJ 08012, <609) 227 1383,

STOLEN: FM 278 2 meter, stolen from car. Has 410306102 engraved on back and side. Contact Allen Eskind W4ZLW, 6104 Hickory Valley Kd.. Nashville TN 37205.

you got to lose? Even if you blow out a few ICs while learning, they can be rep!aced for less than a buck. The initial investment is one of the cheapest available ¡n amateur radio, when viewed in terms of the fun you will eventually have.

Sei aside a little something each week and soon you'll have enough for the power supply, breadboard matrix, and a handful ol ICs and pjrts. After that it should be downhill all the way. ■

LIFTED Drake TR22 s/n 640995 was stolen from my car located in the parking lot al 2121 East 63rd Street, Kansas City MO between 8 am and 11 am CST on Thursday April 8 1976 The radio was marked on the chassis with my Social Security number and amateur radio call. Anyone with inFor mation concerning this radio is asked Lo contact the Kansas City MO Police Department (816 J 842 6525 or K0IDJ.

TAKEN: Drake Model ML-2, I2chan nel all xtaled, serial no. 11239. Touch Tone pad attached to top. CaU K2YKE attached to side and marked several places inside. Stolen from my car in Buffalo, New York April 9th. Ken Haas, 243 Crosby Blvd, Buffalo, New York 14226. Phone 716 834-4083,

RIPPED OFF: Hearh HW 202, series 00316 transceiver. Modified: BNC antenna connector, scanner with LEDs over top (extra) barswitch. Three switches to left not connected Righl switch turns scanner on/off. Wires were cut at back panel. Contact Dick ElEis W5YCK, 104 West Avenue A. Alpine TX 79830, phone 915-837 3728.

PILFERED: Regency HR21 s/n unknown, Crystalled for 34 T7'67, 25/85, 88'88, has owner s name jnside. Stolen from Dwane Barber WA0WWO, RFO 3 Box 353, Greeley CO 80631

MISAPPROPRIATED Icom IC22A, s/n 3401802. Crystalled for 94/94, 34/94, 22/82, 28/88, 52/52, 16/76, 37/97, 87/27, 19/79. Calf is engraved on back, accessory plug wired for TT, PTTr and 455 kHz output, Stoten from Bill Croghan WB0KSW, 1030 WP Colorado. Colorado Springs CO 80905. phone 303 471 7504.

TAKEN Regency HR-2A, s/n 04 07989 taken from car in Harrisburg PA. K3NVO 49538*8556 engraved on chassis. Has scanner board mounted over receive crystals and four red LEDs mounted vertically on left iront panel for channels one through four. Call or contact Ronald Kaullen K3NVO, 6326 Blue FEag Ave , Harrisburg PA 17112.

Oscar Orbits_

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