Power supply build question

[Disabled_shredder]

I am building a submini amp from scratch in design and I'm on a very tight budget. Also I am more versed in repair than design. My question is I am using a Hammond 269ax power transformer that has a 250vct at 115ma. After diode rectification that would be 350v. Way higher than what I need. I know user ur 12 did a submini design with this power transformer and I saw In The post he referenced his voltages being under 200v. So either a does anybody have a copy of the schematic for that power supply for the lil devil amp or b will I get alot less volts through this power supply than I'm expecting. I will have 5 stages of filtering and need to range from 180-185 down to 150 or so. I have tried doing the math for calculating the voltage drop and resistor values but I'm not very good with theory and I do not want to get tied up with alot of money in trial and error (I know that's part of it but I want to reduce cost as much as possible) and get close on the first try, which I think is reasonable in request. I am using a pair of 5902s on the out put and 4-5 6112/6111s between preamp pi and effects loop. Any help with figuring out the ps side would be awesome.

[martin manning]

250V CT means 125VAC on each half of the secondary, so silicon diode rectified voltage will be a bit under 125*1.414 or 177 at 150mA.

[Disabled_shredder]

Ok that's more logical. But why 125 if its 125-0-125 would it not produce 250 then recification. Does that question come across right or is it still stuck in my head? Maybe you could elaborate why you say only half of the transformer voltage.

[martin manning]

The CT is grounded (the "0" in 125-0-125), so you have two 125V RMS sources that are 180 degrees out of phase. Each of those is half-wave rectified before being combined at the reservoir capacitor so it's the peak voltage from each sine wave that is delivered to the reservoir, not the peak-to-peak.

[Disabled_shredder]

Thank you that made perfect sense. I have fixed more than enough amps for this to be an embarrassing question but it's one that has never mattered until now. Now by chance you wouldn't have a simplified formula to calculate the sections like the Duncan tone stack calculator kind of jig? I'm not good with math and equations and I'm not sure I'm on point what I have read you start at the end and work back to the beginning but then that makes me continuously have to go and change the last set of numbers to make the voltage drop right for that section.

[SoulFetish]

You may find this helpful. Hammond made this document available on their website to shed some light on what you can expect from rectifier and input filter design. A single power transformer can be used to produce several different DC voltages and current rating, depending on which rectifier is used and what kind of input filter is used directly following the rectifier(ie. capacitor, choke, etc.)
Here is the PDF: