This General Electric circuit, in a documentation from the 1960s, allows the use of high resistance resistive sensors with unijunction transistors in a relaxation oscillator.
This optically coupled circuit was found in the February 1968 Radio Electronics magazine. The...
This limit detector or window discriminator uses an old operational amplifier, but it can be...
We found this circuit in a 1974 integrated circuit manual. Operational amplifiers can be of...