This circuit was found in a 1966 EEE. What it does is it converts the logic levels of 0 V and +4 V into -6 V and +6 V. Some older type transistors can be replaced by modern equivalents.
This circuit is from the LM317's own manual obtained from an old documentation. The IC should be...
This circuit uses separate sources for the power supply and the operational stage. The output...
This circuit reproduces the signal from a nearby transmitter in a phone. The earphone must be...