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.
Experiment 1: Just a diode
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.
Experiment 2: a diode bridge
Result 2: This is similar to the circuit above, just more voltage drop because more diodes are involved.
Experiment 3: Through a capacitor
Result 3: the capacitor blocks DC, but allows AC through, with some voltage drop.
Experiment 4: Capacitor parallel with load.
Result 4. No change because there is nothing between the test points.
Experiment 5: through an inductor
Result 5: there was no change.
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
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