Found in a Hands On Electronics from the 80's, this circuit activates a relay with alternating touches on the push-button. The relay depends on the supply voltage.
This simple amplifier stage with a transistor has a linear response from 25 Hz to 120 kHz. The...
The output transistors can be the TIP41 and the BD135 and BD136 drivers. TR1 can be a BC558 and...
The general-purpose thermostat shown in the figure uses a high-resistive thermistor as a sensor....