We found this circuit in the Linear Applications Handbook by National Semiconductor. It uses the LM3900, an operational transconductance amplifier as a base. Q1 can be a 2N2222 or similar.
This circuit is from a documentation from the 70s. The circuit uses logic gates of the time, which...
We found this circuit in the October 1988 Radio Electronics magazine. The circuit is still current...
This CMOS logic-based circuit was found in the April 1974 issue of Radio Electronics magazine. The circuit...