RADIO ON THREE TRANSISTORS.
RADIO ON Three TRANSISTORS.
N. Marushkevich , Minsk
The radio station is designed for two-way communication in the range of 27 MHz with amplitude modulation. It is assembled on a transceiver scheme. The cascade on the transistor VT 1 serves as a receiver and transmitter. Amplifier transistors VT 1 and VT 2 in receive mode amplifies the signal allocated by the receiver, and in transmit mode modulates the carrier .
When installing special attention should be paid to the location of the capacitors C10 and C11. They are used to prevent self-excitation. If self-excitation still occurs, then you must connect an additional several capacitors of the same capacity.
About customization. She is very simple. First, with the help of a frequency meter , the transmitter frequency is set, and then the receiver of another radio station is tuned for maximum noise suppression and highest signal loudness. The coil L 1 adjusts the transmitter, and the coil L 2 tunes the receiver.
Supply voltage - 9-12 V.
The communication range in the open area is about
The receiver current consumption is 15 mA,
transmitter - 30 mA.
Telescopic antenna -
Case dimensions - 140x75x30 mm.
Tr 1 - any small output transformer.
Ba 1 - any suitable in size speaker with a winding resistance of 8-10 ohms.
DR 1 - DPM-0,6 or self-made: 75-80 turns of sew 0.1 on the resistor MLT 0.5 W - 500 kOhm.
The remaining parts are of any type.
The coils are wound on frames with a diameter
Printed and circuit boards - in fig. 2 ð