I’m trying to figure out whether I need to go and buy a new set of capacitors for building a universal PSU to power an M2x or if these will be ok as I have a bunch of them lying around.
SLPX153M050H4P3 Cornell Dubilier - CDE | Mouser
The voltage rating and capacitance seem like they’d be fine. Just wondering about the quality?
SLPX153M050H4P3 Cornell Dubilier - CDE | Mouser
The voltage rating and capacitance seem like they’d be fine. Just wondering about the quality?
Those will do fine. Nothing wrong with their quality; should be similar to Nichicon, UCC, Epcos, Panasonic, etc.
Cheers,
Jeff.
Cheers,
Jeff.
Is vishay fep30dp suitable as rectifier diode for this power supply? They are huge, the biggest diodes I have ever seen.
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Great thank you. I'm planning on powering a pair of lm3886 amp boards with this, kind of overkill, but this is what I have to work with. So I would want an output voltage between 25v to 30v with load. Which components on this power supply may I skip since it is not powering a class a amp?
Using the parts and pieces you already have on hand is always important, and yes, it’s overkill, but what the heck, it’s DIY. 🙂
Output voltage is dependent on your transformer. What transformer do you have?
You don’t need a ton of capacitance for a LM3886, I’d just populate one cap per ‘corner’ of the CRC. Or use smaller caps, I.E., no need to spend a bunch of money. No need to make it look like a Class-A PSU with enormous caps, it wont make any difference.
Don’t populate the output snubber. Input snubber is fine to use.
Output voltage is dependent on your transformer. What transformer do you have?
You don’t need a ton of capacitance for a LM3886, I’d just populate one cap per ‘corner’ of the CRC. Or use smaller caps, I.E., no need to spend a bunch of money. No need to make it look like a Class-A PSU with enormous caps, it wont make any difference.
Don’t populate the output snubber. Input snubber is fine to use.
Fantastic information, thank you. Off to mouser to order the caps and the resistors.
Edit:I have a transformer 250va trade that outputs 36vac and an antek 200va that outputs 28vac
Edit:I have a transformer 250va trade that outputs 36vac and an antek 200va that outputs 28vac
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36VAC rectified will output 50V (VAC*1.4=VDC)
28VAC will give 39V
You need a 0-22, 0-22 VAC transformer
AS-2222 - 200VA 22V Transformer - AnTek Products Corp
Input snubber rs1(2) cs1(2) cx1(2)
28VAC will give 39V
You need a 0-22, 0-22 VAC transformer
AS-2222 - 200VA 22V Transformer - AnTek Products Corp
Input snubber rs1(2) cs1(2) cx1(2)
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oh. well according to the data sheet the lm3886 chip should be able to take the 39 rectified (also with load the actual voltage at the load will be lower). i dont really want to buy another transformer unless i have to.
That is very true, so yes, use the 28v. 
It's a 250VA transformer, its not going to sag much under load, though you'll loose ~1.4v to the diodes.
It's a 250VA transformer, its not going to sag much under load, though you'll loose ~1.4v to the diodes.
can you help me determine the input snubber values? im reading the hagerman article but it is a little too much for me.
i did, it is not. i'd just forego the input snubber for now, but those components are located between the heat-sinks, so if I dont put them there now, i'll never be able to later on. so i got to figure it out and put it there before soldering the rectifier and there will be no changing them.
Without having your transformer to measure please understand that any guess as to the value of Rs (because its the resistor that actually does the snubbing, not the capacitors, and yes, there is such a thing as too much), is going to be a guess. So try this -
0.01uF Cx
0.15uF Cs
30ohm Rs
0.01uF Cx
0.15uF Cs
30ohm Rs
i'll go ahead and try this. there is no way i can do first hand measurments of my transformer and i will probably end up multiple transformers with this board. i have wima 250v 0.01 uf and 0.1 uf film caps and also i have the resistors. i might have 0.15 uf ceramic Chinese no brand caps.