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Like I said yesterday, try an LP2950 linear LDO regulator.The output cap should really be there to smooth out any ripple (which is important) but....
Any reg with a feedback should get a clean voltage reference (hence the cap) but say 78xx (not adj) without fb should be ok with a cap on the input and not much on it's output as the reference is to gnd...
What i'll try is varying loads without the cap (can't see it oscillating personally with a linear reg)
Without this capacitor the part will oscillate.
They're pretty handy, besides as a regulator they make a good reference since they're fairly precise. That's what I was using the LP2950-3.3 for when I got the oscillations the other week - a reference on the input of a comparator.Lp2950 (ok ok, i've ordered one lol)
Well i ordered 10 (3.3v ldo) ...
Good one, glad it's sorted. Now you can get down to the real fun. Ignore the stuff that's over your head - just follow datasheet guidelines for components and you can't really go wrong.I have fitted the Volt reg in my board and it is working fine.
I am not using for anything except to try to understand the basics of how things work.
Most of what came after my last post was way over my head but thanks anyway.
Yep this is what i was talking aboutI would be making sure you have the regulator connected correctly .... those voltage reading I have seen on a reversed connection
He already explained that he had the regulator connected using flying leads and had a bad connection. Going by the output voltage he was getting, it would have been a bad ground connection.Is it possible that you mistook the input and output pins ?
Steve, don't you mean 'appropriate'?but that capacitors have developed to such an extent that it's now a lot easier to get caps with inappropriate (for this purpose) specs.
Steve, don't you mean 'appropriate'?
Right, I get your meaning now.No, I actually mean inappropriate.
There are cautions against using high value ceramic caps as the output caps for certain LDO regulators. These high value ceramics (say, 10uF 6V) are attractive for use on a board populated with SMT components. They're small, they're cheap, and we use a 0.1uF ceramic, so a 10uF must be great, right?
Well in some cases "WRONG". The ceramic caps have a very low ESR, and I've seen regulators (I'd have to go searching to find them now) which specified a range of ESR for the output capacitor to achieve both stability and their published specs.
Actually, google comes to my assistance with this, and this.
Here is another pdf which goes into some detail about the input capacitor.