Hello. I'm following desmith's guide to building a power supply, and I'm using a circuit somewhat similar to his except I've selected some different components due to some size constraints. The main difference is my mosfet is this guy: https://www.digikey.com/product-detail/en/toshiba-semiconductor-and-storage/TPH5200FNH,L1Q/TPH5200FNHL1QCT-ND/5456292
Anyway, my no-load output swings from 250V to 150V over the course of several seconds, during which there is no activity on the EXT pin. The output is basically just dropping due to leakage resistance. Once the output reaches 150V, I see switching activity on the EXT pin and the output quickly shoots up to 250V, and then switching activity stops again. This cycle just repeats. Putting a load of a single nixie on the output does not change the behaviour. If I ground the FB pin, instead of seeing 12V at the output as expected I see something like 300-310V. My FB pin usually sits around 1.7-1.8V as the voltage swings up and down. My Ref pin is at 1.5V as expected. My input voltage is 12V. Can anyone give me some insight as to what is happening? I have attached a snippet of the circuit showing the HV supply portion. -- 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 neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/0d2ed804-8cd3-4003-9549-53152e4be619%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
