This interesting sensor for RF signals was found in an article in the June 1989 Radio Electronics magazine. It is a field strength meter with an LED bargraph indicator.
This symmetric 30 mA x 15 V power supply was found in the Ferranti transistor manual from 1974....
We found this probe circuit for frequency meters up to 10 MHz with a sensitivity of 10 mV, which...
This circuit is from a cookbook to timers. The circuit is triggered by an external signal and,...