Found in a 1980s American documentation, this circuit uses programmable unijunction transistors of the time. The time interval obtained depends on the capacitors that can be changed.
The 1: 1 transformer on this circuit found in a 1967 Electronics World can be wrapped around a...
This simple stage can operate with low frequency signals (audio), driving a small lodspeaker....
This circuit has a gain of 6 and a Q factor of 8.63. Operational amplifiers are common, like the...