Current Measurement and logging

[deburgess]

Currently, I am using an Analog Discovery 3 to study a nonlinear oscillator circuit based on a lambda diode. I would like to directly measure current without adding a resistor (which would alter the parameters of the circuit and could qualitatively change its behavior).  In addition, I would like to study non-periodic waveforms (including chaos) created by driving the oscillator with a function generator.

Can you give me some general advice about the test equipment I should use to directly measure and log current?

In addition, what should I use as a function generator to create at least a 10-V ramp? (The arbitrary wave generator on the AD3 is great, but is limited to a 5V amplitude?

thank you very much,

Don Burgess

[JColvin]

Hi @deburgess,

The Discovery Power Supply DPS3340, https://digilent.com/reference/test-and-measurement/discovery-power-supply-3340/start, has integrated voltage and current readback with its three power supply outputs, one of which is a +1 to +15 V output. Each of the three outputs can also act as an arbitrary generator, but as a power supply (rather than a DAC) you will be much more limited in how fast you can oscillate the signal (probably topping out at around 50 Hz if the load is sufficient).

On a different note, the Analog Discovery Pro ADP5250, https://digilent.com/reference/test-and-measurement/analog-discovery-pro-5250/start, can output a +-12 V signal into a high impedance source with its own AWG, though it does not have integrated readback to go with it. You can measure current through the built-in DMM that is present on the ADP5250, but the sample rate isn't much faster than the DPS3340.

Otherwise, most current measurements for on-board components tend to use a resistor of a known value and measure the voltage drop across that impedance. There are others that instead measure the magnetic change from the current flowing in a wire, but I don't believe there is anything like that for small on-board components, but I could be wrong on that point. Either way, Digilent doesn't have a specific solution for this.

Let me know if you have any questions.

Thanks,
JColvin