This circuit was found in a 90s Popular Electronics. It is used for the acoustic transmitters of 40 kHz, as several found in this section. Transistors support current equivalents.
We found this circuit in an American documentation from the 60's. The transistors are made of...
The accuracy of this circuit depends on adjustments made with capacitors of small tolerances of known...
The figure shows how to implement an OR function with two inputs, using a relay. The relay...