Remote Switching on a PCB

Discussion in 'General Electronics Chat' started by Graemec, Mar 18, 2011.

  1. Graemec

    Thread Starter New Member

    Aug 3, 2007
    I am quantifying the characteristics and performance of a device that includes a photodiode.

    Currently my set up involves the photocurrent generated by a photodiode going into a pre-amplifier and then additional signal processing elements.

    My new experiment involves the use of low current ammeter. The meter is different from a normal ammeter in that it sinks the current rather than being a low impendence element in series in the circuit. I need to be able to switch between the photocurrent flowing into pre amplifier and flowing into the ammeter.

    Obviously I could add a switch to the PCB, however(for reasons I won’t go into) I can’t access the board during the test. There is however cable coming off the PCB.

    I am thinking of using a miniature PCB single pole double throw relay, which I could activate remotely. I've read a few of data sheets and some make reference to a minimum contract current. Values around 10mA seem the norm. As I will be measuring currents in the 1-100nA range I don't know if a relay is a suitable component.

    Can anyone suggest a suitable approach and components to use?