This 1975 tachometer for cars with platinum can serve as an idea for new projects. The components are from the era and a modern equivalent operational amplifier can be used.
Indicated to operate in tube circuits, this preamplifier has 250 V power supply. The circuit is...
The configuration shown was found in an old Poptronics but can be easily assembled using a common...
Found in a 90s Popular Electronics, this simple circuit turns on a light when the light stops to...