This configuration is from the 70s, having been found in an American documentation. The transistors can be BC549 for Q1 and BC548 for Q2.
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...