This circuit is from a publication from the 70s. The operational amplifier is from the period. Modern equivalents according to the motor current must be used.
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...