A while back, I bought a few DDS modules through eBay.  I used code from NR8O to program one of them and started pulling parts from the bin and pushing the output signal through the parts and into a load resistor.

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Experiment 1: Just a diode

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Result 1: the large waveform is the input signal (A), and the small bumps are the scope channel 2 (B). The diode rectifies the signal, which is why the bumps are only going up (and not down). The forward voltage drop on the diode is why the bumps are so small.

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Experiment 2: a diode bridge

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Result 2: This is similar to the circuit above, just more voltage drop because more diodes are involved.

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Experiment 3: Through a capacitor

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Result 3: the capacitor blocks DC, but allows AC through, with some voltage drop.

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Experiment 4: Capacitor parallel with load.

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Result 4. No change because there is nothing between the test points.

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Experiment 5: through an inductor

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Result 5: there was no change.

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Experiment 6: inductive load

The video below shows what happened.  I'm sure there's an explanation of the instability, but I don't know the explanation.

Stay tuned for experiments 2!

73 de KE8P


Category: Arduino

About the Author

Andrew is the owner of this blog and enjoys computer programming, building things, and photography. He's a pretty busy guy, which explains why updates to this blog are so infrequent.

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