Sourcing components for this PSU:

http://www.qsl.net/yo5ofh/projects/vps/vps.htm

It has been mentioned to use solid Tantalum caps for C1 + C3 at least, but would a Electrolytic cover it? The schematic also calls for C1 to be 2200uF @ 64V, but all I can source (so far) is a 2200uF 50V Electrolytic - should I be concerned of the voltage rating if I only use a 25VAC transformer?

 

50V will be fine, and ignore any references to tantalum caps. At one time they were praised due to tolerance, low ESR & stabiltity but with the modern common electrolyics being so good the tantalums have just fallen inrto a high $$ niche spot.

 

Tantalums tend to go off like firecrackers if left un-powered for an extended period of time.

Use fresh electrolytic caps. You can help the response time if you parallel the large electrolytics with some much smaller low-ESR caps.

 

Another thing I keep forgetting to mention is that it's definitely worth the few extra pennies to buy 105*C electrolytics as opposed to the ones only rated for 85*C, the life at room temperature or not much above it can be anywhere from 5 - 20x as good.

 

While tantalums are better than average caps I have to agree with Wookie on this one. Never had one go off like firecrackers, more like match heads. More than one too. I remember working on a test fixture that had an intermittent noise problem with cold spray when one went up. It was in the middle of a board I would have to fix (no options) and I had the cold spray in my hands, so it made an impromptu fire extinguisher. Even with the cold spray continuously dousing it it still burned to the ground. These are not flame proof components.

 

Thanks,
I've got a good assortment of Low ESR Caps, and I'll have a look for some 105deg ones too!

Thanks guys