248

KITS - R.F PROJECTS

Two-Stage FM Transmitter, or Wireless Microphone

A powerful little circuit withsurprisingly good audio qual-ity. Can transmit up to about1/2 mile in open country.This is probably the mostpowerful FM transmitter thatyou can legally purchase. Anelectret microphone is usedto add sensitivity. The circuit can run on six volts, greatest out-put is at 12 volts, but use 9 volts and short antenna wire tostay legal.

No. 80-320

FM Telephone Transmitter

Miniature transmitter attach-es to the phone line andtransmits the conversation.Transmits 200 yards andmore in most installations.Tunable to clear spot on theFM band of your radio.Completely parasitic; i.e.uses the power from the telephone line and needs no battery.The circuit might be used to share or record conversations, butplease do not use illegally.

No. 80-160

Sound Activated FM Transmitter

Sound turns on the transmitter,which operates in the FM radioband. A neat way to catch a thiefin another room or garage. Thevolume of sound needed to trig-ger the circuit is adjustable. Thetwo stage transmitter has goodrange and the circuit powersdown unless it “hears” sounds;reactivates with a sound.

No. 80-280

3 Volt FM Transmitter

The most powerful circuit we’veseen that operates on such lowvoltage (just two AA cells). A rangeof 100 meters can be expected andgiven a good antenna and goodconditions, 500 meters is not unusual. Can be operatedon up to about 9 volts. Transmits to the FM radio band.Teaches basics of transmitters. Microphone is included.

No. 80-070

This is the Cadillac of FM transmit-ters, and wireless mikes . Transmitsin the standard FM radio band; tuneto open frequency. Varactor tuningresults in stable signal, free fromstray capacitance and drifting.Sensitive, picks up conversationsfrom several feet. Powerful opera-tion on a nine volt battery but could use 12V DC if you are goingfor distance. Easy to build, good for teaching beginners with just abit of supervision.

Varactor Tuned FM TransmitterWireless Mike Kit

No. 80-065

One Chip AM RadioThis is a complete AM radiofor the standard broadcastband, most of which is on asingle IC. Other compo-nents, such as the coils andvariable capacitor to make afinished radio, are included.The IC is the RF amp,detector and AGC circuitry.The IC’s output drives a two stage, transistor audio amplifierand 3” speaker. Operates from 9 volt battery. A good kit forbeginners to see and build.

No. 80-630

R.F. Bug Sniffer (Locator)If someone put a BUG (listening device)in your meeting room, would you know it?Today’s small circuits make listeningdevices too easy to conceal to ignore.You may want to assemble this one forresale to nervous and needy users. A highquality circuit, should be considered evenby the professional. It will detect anytransmitter sending A.M. or F.M. or justC.W. at frequencies anywhere from ten to450 mHz; peak sensitivity is in the 80 to120 MHz portion where many bugswould be found. The signal strength isindicated on a bargraph, so the closer to the source you get, thehigher the indication. With some practice, you should be able tofind a covert transmitter to within a few inches of its location.“Professional” bugs, placed by serious operators can be foundeasily. Operation on 9 Volt battery for portability.

No. 80-990

FM Stereo Transmitter

This is a circuit that will broadcast CD qualitysound to your FM Walkman, home stereo orautomobile radio. It produces a strong signalthat will generally cover the average homeand yard. It is stable enough to use even withdigitally tuned FM receivers. Typical usesinclude broadcasting your own music to areceiver at pool-side or in the garden. Or, youcould broadcast from a personal, portable CDplayer to a car radio that has no CD player. School uses include run-ning a “broadcast station” from another room as a speech class exer-cise. The unit is powered by a 9V transistor battery, or you could use anAC wall adaptor.

No. 80-060