This circuit uses a diode as a radiation sensor. The operational ones are old because the publication is from the 80's, but modern low voltage equivalents can be tested.
The transmitter shown can reach around 100 meters depending on the location and sensitivity of the...
This circuit converts a positive CMOS supply voltage to a negative one. We found it in a 90s...
The circuit shown in figure 5 generates square signals based on a transconductance operational amplifier...