This simple tone control using two transistors was found in an Electronics Today International of the 90s. Transistors are general purpose NPN types, like the BC549 for greater gain.
This circuit uses a FET to drive an LED with constante currente. The current up to 20 mA can be...
This circuit was found in a 1999 publication. Its purpose is to flash two LEDs according to the...
With this voltmeter with high input resistance, voltages from 10 mV to 50 V. can be measured. FETs...