This step of two transistors has a high input impedance due to the use of FET. We can use BF245 for this function and the bipolar can be BC548. The circuit is from an 1975 American documentation.
This circuit came out in a publication called Electronics Handbook of 1993. The circuit triggers an...
This circuit detects the 60 Hz signal from the power grid captured by an object, activating a...
This circuit shows how to use a fixed 5 V regulator on a variable 1 A source. The integrated...