[sdiy] pico ampere stuff

[Czech Martin]

the other day I soldered a simple pico ampere meter, just
a 3140 follower with a 6nF polystyrene cap @ the input.
Both, + and - leg bend up in the air (air insulation).
The droop rate was as described in the data sheet,
about 2pA leakage @ room temperature due to ESD zeners.

Now, that is boring. So I decided to use this circuit to look for leakage
on my favourite predrilled paper/card/pertinax boards.
Soldered to pins in @ minimum hole distance, no fancy solder,
no cleaning. Result: not a single pA more leakage even
@ elevated voltages at the gap.

So my pertinax boards are not that bad. However, aging and humidity
can wreck leakage sensitive circuits, so cleaning and good solder
flux is certainly a good idea.

Next thing is to make a 200Meg resistor in order to have
a real pico ampere meter (current to voltage converter).

Straight forward circuit.


m.c.