Hello every body,

I need to detect a low value of current in a circuit(1.5uA to 50 uA) and i have to use just transitor(s), resistances and capacity(ies).

About resistance, i think that i have to choose some high values to detect these current values(10 Mega, 1 Meg or...).

can you help me please to define this scheme.

thank you.

badrove

 

the skie's the limit if you can use as many transistors as you want. where exactly is this small current you trying to "detect".

i perhaps would use a very low precision resistor (1% or .5% .05ohm) in series with this small current, then using the transistors you have build a diff op-amp with large gain to sense the small voltage drop across that resistor. however, using discrete transistors to build a usable high gain diff op-amp may prove to be cumbersome and futile.....