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.
I found this circuit in an English publication from 1989. This configuration can be mounted with...
This circuit can be used to amplify signals up to 150MHz. The JFET can be MPF102 or BF245 and the...
In this circuit of 1987 the player has to briefly press one of the keys trying to hit which LED...