Silicon Diode Current Source Boxes

Four boxes built at Northwestern University

Design specifications

Outputs: 4 @ 10 microA each
Powered by: batteries
Accuracy: +/- 0.1 microA
Temperature drifts: 0.1 microA per 10 degrees C or less Compliance: 3.0 Volts

Batteries
  • Separate power for each of the four components
  • Battery life: 1-2 months
    • Layout
  • Box: must be durable (strong). Metal preffered for this reason
  • Current outputs: isolated BNC
  • Battery Monitors: isolated BNC
  • On/off switch


    • Kevin says: +/- 15 V is the way to go. Battery life will be ~1 week due to awkwardness of building low-current supplies with amps.

    Testing the silicon diode current source boxes

    Testing SPARO Silicon Current Source Box
    Temperature Device Resistance Current
    Room temp 50 kOhms 10.7 microA
    LN2 100 kOhms 10.1 microA
    300 kOhms 9.6 microA

    (Nominal compliance spec is 2.5 V = 250 kOhms)

    Put in 8.4 V battery: current at 250 kOhms is same as for 9.6 V battery!

    Battery sucks up to 350 microA when in operation.

    Battery life should be 10 times better than previous version (built in 1995) as previous version sucked 3 mA for a nominal life of 7 days.

    I believe Kevin's estimate of 6 weeks. Could be even longer.