This circuit is from a documentation from the 70s. The circuit uses logic gates of the time, which in many cases were arrays of transistors allowing use as audio amplifiers, as in this case.
This circuit suggested by Intersil, provides a Kelvin scale of 3 and a half digits in a 7106, with...
This circuit suggested by Motorola can be used as LED high frequency modulator. One possible...
This LED diode test is suggested by the Texas Instruments optoelectronics manual. The transformer current...