Is your transformer (inductor) getting too warm ? It's possible that the peak current is larger than Isat; at saturation the magnetic efficiency drops way off.
It's not easy to measure the inductor current, because parasitics are introduced by the scope-probe. Most often, the ground lead picks-up noise and makes your signal look far worse than it really is. I remove the ground clip and the plastic shroud around the probe tip. Then, I wrap a few turns of bare wire around the exposed ground of the probe (approx 1-2 mm from the probe tip) and solder that to the closest GND connection. This minimizes the coupling of noise to the scope's ground; I've actually removed several volts worth of noise using this technique. This will allow you to view clean *voltage* waveforms. If you dont have an expensive current probe (I certainly dont), you will need to insert a small resistance (100 milliohms) and measure the voltage across it to infer current. Make sure it is NOT a wirewound resistor, which is inductive. The current waveform should look triangular (increase linearly from 0 to peak when the switch is on, then decrease to 0 rapidly when the switch turns off). Once you have that you can start debugging where things are going wrong. Converters always seem to run beautifully with no-load; when you start loading them down, all kinds of things happen. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/c37e71e9-ee0a-4da5-9894-311b19ff1fb6%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
