This circuit is from Mullard 1969 documentation. The circuit operates at a relatively high supply voltage and has a 10 Vpp output. The transistors are of the time, but admit equivalents.
In the figure we have a simple timer with two voltage comparators of the four of an LM339. The...
This circuit can be used in a signal level indicator with LEDs. The circuit is from an Electronics Now...
This circuit, found in an old magazine of the year 1968, uses a Power germanium transistor. This...