This circuit is from a 1978 Texas Instruments optoelectronics manual. The trimpot adjusts the LED current. Other currents can be adjusted if they are within the capacity of the FET.
This circuit was found in a PC documentation from 1996. It can be used as a shield with modern...
This circuit measures the power of a transmitter being sandwiched between the antenna output and the...
This circuit was found in a 1968 Hughes documentation. The transistors are from that time. The coil...