Simple walkie-talkie with three transistors

This is a shortwave radio station contains only three transistors. The easiest walkie-talkie to repeat novice radio amateurs. The design was taken from an old magazine, but its relevance is not a bit lost. The only thing that is outdated is the radio components that need to be replaced with modern analogs, as a result, the characteristics of the radio intercom will improve.

Radio station

Simple walkie-talkie with three transistors
The circuit is simple, especially if you understand its operation. I suggest you immediately visually divide it into the left side with one transistor and the right one with two transistors. Transistor VT1 assembled transmitter and receiver at the same time. When the switch closes the contacts "1", the radio is in the receive mode and this transistor operates in the mode of the supergenerative detector. And when the contacts are closed in the "2" mode - this is the transmission and the transistor works as a master oscillator. With this, I think it is understandable.Transistor VT2, VT3 assembled a simple low-frequency amplifier, which, depending on the position of the switch, either amplifies the signal from the microphone and transmits it to the transmitter, or amplifies the signal of the supergenerative detector and transmits it to the loudspeaker. By the way, the loudspeaker and the microphone are one and the same element - the high impedance DEM telephone cap.

Parts for a radio station

Coil L1 is wound on a frame with a diameter of 8 mm with a ferrite core turn to turn and has 9 turns of PEL wire with a diameter of 0.5 mm. The coil L2 is wound over the coil L1 and has 3 turns of the same wire. Coil L3 has a diameter of 5 mm and contains 60 turns of PEL wire with a diameter of 0.5 mm. You can use the primary winding of the output transformer of a transistor receiver as the L4 inductor.

Antenna design

A simple walkie-talkie on three transistors
I made the antenna from thick aluminum wire, with a piece of insulation, over which the L3 coil was wound.

My modernization


I made such a walkie-talkie back in school, but then I changed all the transistors to more modern and high gain.For example, I replaced VT1, VT2 with KT361, and VT3 with KT315. Now I would certainly change the polarity of the power supply and the polarity of the capacitors, replace all the transistors from the npn structure to pnp, and pnp to npn. Well, I would install modern transistors. There are no special requirements for transistors, so absolutely any fit. The author of the scheme says that the radius of action of radium of the same type in open areas is 100-200 meters. I also overclocked such radios to 500 meters, for this I used modern transistors, I increased the antenna to 900 mm, plus I increased the generator current, replacing the 100 Ohm resistor with 50 Ohm. Someone will say that all because of the increase in the antenna, with which I do not agree, and I will say that with the “native” antenna I was able to communicate by 300 meters.

Setup

If you assembled the radio correctly and from serviceable parts, then the whole setup will be reduced to tuning the coil L1 at a frequency of 27 MHz. This can be done with a subscript core or with a capacitor in the loop.


Related News


Smart Design in Barcelona
Sock Snowman
22 uses of lemon
Simple as five kopeks Curd dessert
Always put onions in the freezer
Decorating a wooden antique watch
Vase in papier-mâché technique
We select the wardrobe in the style of Lolita