This Hughes circuit is from 1968. Equivalent modern components can be used. The input impedance is 1000 M ohm.
This 2002 circuit uses many more electrical components than electronics. The keys are common, and...
This circuit is from the National Semiconductor CMOS manual of 1977. What this circuit does is to...
This circuit warns you if you forget to turn off the car light and leave it. The circuit is from a...