This TTL circuit was found in an American documentation from the 80s. The components are common in the series and the supply must be made with a voltage of 5 V.
This circuit was found in a 90s Hands-on Electronics. The transistor can be a BC548. What it does...
In the figure we show how to use an LM324 as a voltage comparator the reference voltage is...
This circuit is based on an LM3900 transconductance operational amplifier, found in 1992...