Small Power Regulated Power Supply

[teleman]

Yes!

[mjf]

hello.
i often put some indikator lights at the output of the voltregs............a resistor with a standardled (red,yellow or green ) in series can show proper function or not.
with 9v output minus 2volt for the led and 10ma ledcurrent you get a res around 680ohm.......750ohm/0,5watt.
greetings

[teleman]

Thank you.Since there are already 2 holes drilled on the front plate for LEDs..I too was thinking if I should have these or not ..since,I thought that they also introduce some noise in to the circuit! If you think it is negligible,then I will definitely connect the LEDs.

[mjf]

good morning.
.......so far never had a problem with led - noise........iirc luxman and others used (red) leds as a volt reference in their phonopreamps and so.
a led at the output of the reg gives you a continuous current draw..........

[teleman]

Good day to you too!
In that case I will connect 2 LEDs & post a pic. of the competed PSU.Thanks for your ever willing help & advice.Much appreciated as always!

[mjf]

.......here is a foto with a lm317/337 psu once i have built.
greets.......

[teleman]

Nice work! Did you have any problems with dc voltage symmetry without the trim pots? What voltage are you running this at? I have not learned PCB making properly..in retrospect should have payed more attention in class!

[teleman]

Oh! I almost forgot to mention...I'm using LM 317T/337T reg.but not sure of the quality of these as these are 2 different,dubious brands bought on the E-Bay!
I've also connected a commercial type mains IEC Filter socket!(used the maxim
of throwing everything when one's in doubt!..seems to work all the time,,ha..ha)
Anyway,once I connected the LEDs,the voltage drift stopped considerably & didn't rise even with the the increase in temperature!.

So we can perhaps assume that the small loads presented by the LEDs actually help stabilizing the circuit as already mentioned in the DATA sheet.

I would like to hear from anyone else who has experienced this,The data sheet actually mentions about this with regard to no load conditions vs temperature.

I will try to plot the dc o/p on my scope & see how it performs.

The additional or alternate parts list would be;
Prim:220/230 Second;0-9-0-9 12VA Transformer.
Mains IEC Filter socket =1A
2x200mA slow-blow fuses (depending of course on the current drawn by the trafo!)
LM317T
LM337T
2x 5k 1/2w trimm pots
2x 1N4002 additional clamping diodes
2x tri-color LEDs with red /green retrained & other 2chopped off from the LEDs!
2x120ohm R
SWITCH CRAFT DC chassis plugs & sockets.

That's all folks!

[mjf]

Did you have any problems with dc voltage symmetry without the trim pots? What voltage are you running this at?

.......at the moment at +-18v,but i use this reg's with different applications too.so it is easier to get symmetry with trimpots for me (5k on the foto,but with lower output i would use 1......2k).the foto is without heatsinks..........and at the copperglad downside there are sometimes big foilcaps built in.

[mjf]

[QUOTE=teleman;1982244]Oh! I almost forgot to mention...I'm using LM 317T/337T reg.but not sure of the quality of these as these are 2 different,dubious brands bought on the E-Bay!

........what is "dubious brand"? i have regs here from: national,fairchild,texas instr.,ons(motorola)............


I've also connected a commercial type mains IEC Filter socket!(used the maxim
of throwing everything when one's in doubt!..seems to work all the time,,ha..ha)

.....good idea - going the easy and save way.

greetings............