Operating at a frequency of around 180 kHz, this transmitter was found in a Science & Electronics of 1970. The coil has 34 turns of 22 wire. The transistor can be the 2N2222.
The source used in this timer is of the type without transformer and regulated by the 7 W zener. The...
This high-gain digital amplifier uses general-purpose transistors. The supply voltage is logic...
The circuit shown in the figure has temperature compensation. Phototransistors can be of any type...