This classic walkie talkie consists of both 27MHz transmitter and receiver all in one circuit. Nearly all the components in the 4-transistor circuit are used for both transmitting and receiving making it simple to build and economical at the same time. The frequency-generating stage only needs 27MHz crystal to be removed and it becomes a receiver. Next is a three transistor audio amplifier with very high gain. The first transistor is a pre-amplifier and the next two are wired as a super-alpha pair, commonly called a Darlington pair to drive the speaker that is also used as a microphone. The use of telescopic antenna will provide better reception and transmitting range. Use two identical walkie talkie circuits for two way communication.
Build Accurate LC Meter and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging and reset function to make sure the readings are as accurate as possible ... [more]