Found in a 1965 General Electric Hobby Manual, this timer was originally created to operate with photo magnifiers of the time. The circuit can be adapted for other purposes.
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....