> On Nov 21, 1:53 am, Dekatron42 <[email protected]> wrote: > Hi! > > I need help in designing a power supply with the MC34063 which will > deliver +475V @ 50mA for running a bunch of dekatrons. >
Wow ! That's over 100 dekatrons ! Whatcha mak'n ? What Jon says is true. You're gonna need a beefy coil and power FET. Just some added info. The MC34063 design has a nominal efficiency of 75%; 80% if everything is perfect. 475V x 50mA = 23.8W. At 80% that's 30W in, and 6W of that is waste heat.At 75% that's 32W in; 8W of heat. That's a lot of waste heat to dissipate in a small area. The best inefficiencies are achieved with the MAX1771. 85% is realistic expectation. At 85%, the input power will be 28W, with only 4.2W of waste heat. Here's a link to Nick's MAX1771 page: http://www.desmith.net/NMdS/Electronics/NixiePSU.html You can test it with both with, and without, the doubler. Adjust it for 475V out straight, and test the results, then at 240V out, with a doubler (to get the 480V), and test it. See which one works better. Also, lower your voltage to 450V, or even 400V. What kind of dekatrons are you using ? If you can get away with it, use the 400V. At 50mA, that's 20W, or 15% less. 23.5W in at 85% efficiency; only 3.5W of waste heat. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
