Dummy Load - Oscillation Problems

Stephen Coates' Website - stevecoates.net

Created: 17th November 2012
Updated: 15th December 2013

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Electronic DC Load

Oscillation Problems

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As I mentioned on the main dummy load page, it was easy to get the circuit to oscillate. This page is just here to show the circuit that caused it, along with some photos of the oscilloscope, showing the weird waveforms obtained.

Circuit Diagram

This circuit diagram is different to the one on the previous page. The capacitor is in a different location.

Oscillating Dummy Load Schematic


Here are some photographs showing the various waveforms measured at the top of the 1R resistor. The multimeter shows the current in Amps.

In this photo, we are into the power supply's ripple:

And with that capacitor removed altogether: