This amplifier for electrometer can work with currents of 0.1 pA in a band of 1 Hz. The circuit is from NASA in a publication of the 60s. Transistors are general purpose types.
We can either supply this circuit with 12 V if we use a relay for this voltage as well as 6 V if...
Two NAND gates are used in the configuration shown here to perform as a monostable triggered by...
Frequency and active cycle of this circuit are fixed by the two crystals that may have different...