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I am going to use a 800vct Triad PTrans of 200ma current capacity. The filter configuration will be inductor, capacitor, inductor, capacitor. Those values are 3H x 20 uf x 7H x 120uf. I wanted to know how would one determine what the unloaded and loaded voltage that would be at the end of the filter. I will also be using a tube rectifier. I am trying to get a B+ of around 400vdc with a 5AR4 rectifier. Thank you in advance, Dak
Follow Ups:
I think it is important to understand that if unloaded a choke input supply gives you 1.4X the secondary voltage or around 550V. This means you should use at least 600V caps to avoid problems if a low or no current situation happens.
I would just build it as a pure choke input supply and then slowly add capacitance before L1 until you get near your desired voltage. I find that 1-2uf typically gives me a DC voltage close to the secondary AC voltage (i use mercury tubes) so I would figure you will need something like 2-3uf to get your 400V.
dave
That is about what I am expecting. I have room under the chassis to add on some 2.0UF X 600VDC PIO caps that should zero in on my target voltage. the 2nd cap is 2 x 10uf 600vdc PIO GE Pyranol which should be more than enough in my app. I should have the amp ready for real world testing by tomorrow. Thanx for the tip and assistance. regards, Dak
This is about what your power supply would look like as designed. Just under 350v.
Hi Chip, thanx for psudding up the variables. I should have mentioned that the DCR of the second inductor is around 100 ohms. Sorry for leaving that out. The first inductor DCR is correct.
Well, at least I now know that I will be close to my needed voltage and I can play with some of the values to get what I need. Thank you for helping. cheers, Dak
400v
Both of these use the step function simulation for current after 1 second.
I use the PSUII power supply simulator. The transformer HV winding & choke winding resistance must be inserted for accurate results. Additionally the capacitor ESR should be inserted as well, but is not as critical as the winding DCR.Performing an educated guess at the transformer & choke winding DCR, 322 volts @ 200ma & 495 volts @ 10ma (bleeder resistor).
Wanting 400 volts, change the rectifier tube to a 5R4G and add 10uF capacitor for a CLCLC. The simulator indicates 390 volts @ 200ma. If the transformer has a 115 volt primary and your line voltage is 120 volts, that 400 volts should be achieved. Load at 10ma produces 531 volts.
Notes-
Simulation included 31 ohm DCR for power transformer, 30 ohms for 3HY choke & 60 ohms for the 7HY choke.
I prefer a 5R4G rectifier due to the high PIV rating. It should not arc inside the tube.
I would use caution using a new manufacture 5AR4 on a 800 VCT winding. A NOS 5AR4 should be ok.Capacitor input is more demanding on a transformer due to the higher peak to average current demand. About 140 degrees F is the maximum temperature I recommend for a vintage power transformer.
Edits: 03/03/15 03/03/15
Hi Sony, thank you for checking the simulation. I was going to download PSUD but I also read some blogs about how you can expose your computer to viruses and cyber attacks with that software. So, I thank you for running the sim for me.
I have lots of Mullard and USA made 5AR4 and I don't bother with the currently made ones.
Once I get the amp set up with the output trans and tubes I can play with adding another cap to the filter supply to adjust the B+ voltage. Thank you for the help. tc, Dak
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