Pages: 1 [2]   Go Down
Author Topic: LM317LZ - how complicated does the circuit need to be?  (Read 1034 times)
0 Members and 1 Guest are viewing this topic.
Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 639
Posts: 34724
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
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.
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 36
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

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

Wales
Offline Offline
Full Member
***
Karma: 0
Posts: 246
Don't take things too seriously
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

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
« Last Edit: March 18, 2012, 03:57:09 pm by Dane » Logged

Germany
Offline Offline
Faraday Member
**
Karma: 59
Posts: 3083
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
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.
Logged

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 639
Posts: 34724
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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.
Logged

Pages: 1 [2]   Go Up
Jump to: