This automotive circuit was obtained from an 80's schematic from the integrated circuit factory itself. The voltage regulator is still common, but the operational amplifier is of the time.
In the figure we have an amplifier from the 50s using the CK721. The circuit has a voltage gain of 5...
This circuit came out in a publication called Electronics Handbook of 1993. Q1 can be a 2N2222 or even...
The integrated circuit used in this small transmitter is not very common today. The coil has its...