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Topic: LM317LZ - how complicated does the circuit need to be? (Read 1 time) previous topic - next topic

Grumpy_Mike

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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.

ebird97

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

Dane

#17
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?

Thanks

michael_x

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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.

Grumpy_Mike

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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