MPJA has some nice dual-primary type power transformers for very affordable prices. An LP-430, which has 4 amp. 12-volt secondary works very nicely using one of the primaries as a secondary, and then putting the real secondary in series with it to add a bit more voltage.
Then, after rectification and filtering, that lashup feeds to a zener diode shunt regulator which maintains 170 volts within a volt or so. Since I am not much up on switching supply design, and since I kind of like big, dumb, simple sorts of things, this HV supply seems quite workable. It's being tested now in a nixie clock which is spread out on solderless boards. It uses 6 of the 8422 tubes and it uses 6 of the 74HC160 counters. Chuck > > >---- Original Message ---- >From: [email protected] >To: [email protected] >Subject: RE: [neonixie-l] Re: Linear power supplies for nixies >Date: Sat, 26 Sep 2015 23:43:05 -0700 (PDT) > >>2. Instead of a voltage doubler, a 'boost' supply is another way to >get >>higher anode-supply voltage. One version (hvsupply.pdf) 'adds' a few >volts >>to the AC line before it's rectified, though it's not isolated. I >use this >>in my big clock to get around +220VDC. The other version >>(neondr_pwrsupp.jpg) accomplishes the same result, but it's >isolated from >>the AC line and that's desirable for safety reasons. >> >> >> >>For the non-isolated supply (hvsupply.pdf), I used a 36 V >transformer. >>There's a full-wave section for 220VDC (D4 & C4). There's also a >half-wave >>doubler (D1, D2, D3, C2, and C3) that generates +440V for the >dekatron in >>this particular clock. R3, R12, and R4 are important for safety >reasons: >>They discharge the capacitors. The role of R12 is subtle, but if you >study >>the circuit you will see the discharge path thru the transformer. >RESD2 is >>one of several high-value resistors in the overall design that >provide a DC >>path between all supplies to reduce ESD susceptibility while the >clock is >>being built. >> >>The isolated supply (neondr_pwrsupp.jpg) is from the clock I'm >currently >>designing. This circuit has not been tested in actual usage yet, but >I have >>run quite a few simulations on it. I still need to run it with >transformer >>winding resistance. The rectifier (XD101) and filter cap (C101) >provide >>about +180V. This clock has fourteen IN-18 tubes, each running at >5mA, so >>it's a fair amount of current. >> >>In order to get isolation, you need a dual-primary transformer. One >of the >>primaries is connected to the AC line and supplies the energy; the >other >>primary winding is used as a secondary winding. When using a >transformer in >>this manner for isolation, you must be careful not to exceed the VA >>(volt-amps) rating and that means you must include the VA >consumption for >>all secondary windings (which includes the primary winding that got >>re-purposed as a secondary). Assuming you use a diode-> capacitor >>rectifier, you will want to calculate the VA rating based on peak >current, >>which is higher than the load current. If you pick a transformer >with a VA >>rating that's too low, you will see more losses (heat). Some will be > >>I-squared-R losses in the windings, and most will probably be from >core >>saturation. The easiest way to determine peak current is with a >circuit >>simulation (LTspice and ngspice are excellent simulators available >for >>free). Or, you can just try it out and see if the transformer gets >warm; if >>it does, get a higher VA rating. >> >>I'll post another article about designing the correct filter cap >value. >> >>-- >>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/a7b6bab1-eb4f-4b67-b19c- >69e5528d9f57%40googlegroups.com. >>For more options, visit https://groups.google.com/d/optout. >> $4.95/mo. National Dialup, Anti-Spam, Anti-Virus, 5mb personal web space. 5x faster dialup for only $9.95/mo. No contracts, No fees, No Kidding! See http://www.All2Easy.net for more details! -- 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/380-22015902714274381%40all2easy.net. For more options, visit https://groups.google.com/d/optout.
