We found this Vox in a 1969 Motorola documentation. Transistors support modern equivalents and the SCR can be a TIC106. The reset is done by a push button.
This circuit monitors extra-low frequency (ELF) fields. We found it in an American documentation from the...
We can use any type of resistive transducer with central resistance in the range of 10 k ohms to 1...
This circuit controls two lamps so that when one increases in brightness the other decreases. The...