Transmitter On A Chip

Lithic Systems

Someone eventually had to do it - and they did. Lithic Systems has announced a comolete AM transmitter on a tiny IC chip. Designated the LP2000, it is capable of 50 MW output on 10 meters when fed by a 12V supply. Operation on 6 meters is also possible with slightly reduced output.

The block diagram shows that the chip isn't a simple oscillator/ modulator as you might expect. Not only does it have two buffer stages between the oscillator and output stage, but it incorporates a power supply regulator andl an audio preamp that is sensitive enough to be driven by a small speaker voice coil. Pretty sophisticated for an AM transmitter! T/R switching is accomplished by a fatch Tngger so the circuit can remain connected to its power source at a times.

Radio Schematic

Fig, J. Schematic of the complete transmitter.

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Fig, J. Schematic of the complete transmitter.

You can't put everything on a chip (yet), so naturally a few extra components are needed to get things working. Not many though - two cofls, an overtone crystal, two resistors and a few capacitors - no trouble should be had iby anyone trying to package the circuit in weird places (like your wrisrwatch .. tor an enemy's ham sandwich!}. No kidding, this little transmitter is bound to start showing up everywhere as a bugt Another possibility is a remote burglar alarm small enough to mount right inside a door knob! Power require ments are +5 to + 15V so those tiny, aspirin size batteries are a natural for the power source. Current drain at 12V is 28 mA,

Lithic Systems is hard at work developing VHF FM and even SSB transmitters similar to this one. Those are certainly going to revolutionize things, Who is going to manufacture the first 2 meter FM nameplate?

Contact Circuit Speci*fists, Box 3047, Scottsdaie AZ 85257 or watch their ads,

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