We found this circuit in a 1985 documentation. The transformer is an old TV flyback that has an exposed part of the core, where 10 to 20 turns of common wire are wrapped.
This amplifier can work with voltages between 12 and 22 V. This means that we can use it in the...
When pressing S1, S2 or S3 this circuit generates different tones for a tone-modulated...
The configuration shown in the figure uses two NPN transistors activating the load when the input...