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Topic: LM317LZ - how complicated does the circuit need to be? (Read 3126 times) previous topic - next topic


i.e. no capacitors

No you can't do this without capacitors and expect no trouble. Put a capacitor across the input and another across ( that means to ground) the output. If you don't have a data sheet that tells you the values to use then you won't go far wrong with a 4u7F for each.


You could try zener diodes. They're pretty cheap and not really all that complicated.


Mar 18, 2012, 09:55 pm Last Edit: Mar 18, 2012, 09:57 pm by Dane Reason: 1
Mike, thanks for your help here!

I've made a model in Fritzing to show how I would wire the vreg circuit.

I'm kind of amazed that, apart from the caps, I had it wired correctly (as per my drawn circuit).

Can someone please confirm this should do the trick?



apart from the caps

Yes, You should turn polarity of C2,  rather switch the connecting wires such that the capacitor + side remains up, which makes the picture clearer as well.


While topologically your circuit is correct:-
For best results the capacitors should be as physically close to the chip as possible and the capacitor leads should be as short as possible.
I would put the regulator chip in three adjacent holes so the capacitors can go straight across the chips and then wire the other stuff from that.

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