This signal injector and tracer (follower) was found in an old American documentation. The transistors can be general use and power is made with one or two common cells.
This circuit using an operational amplifier was found in old American documentation. It can be...
This is a voltmeter with high input resistance. The transistor is germanium. We found it in an...
Two NAND gates are used in the configuration shown here to perform as a monostable triggered by...