Lightspeed Attenuator a new passive preamp

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#2,847
15V at the smoothing cap with no load.
drops to 14.45V with the LDRs drawing current.
drops to 13.87V with the single LED added.

You need proper smoothing cap across the rectified supply.
Try 1000uF or somewhere close, 470uF to 2200uF.

Measure those three conditions again.
 
#2,848
AndrewT said:
15V at the smoothing cap with no load.
drops to 14.45V with the LDRs drawing current.
drops to 13.87V with the single LED added.

You need proper smoothing cap across the rectified supply.
Try 1000uF or somewhere close, 470uF to 2200uF.

Measure those three conditions again.
Click to expand...

Hi Andrew

I'm keeping you busy! 😀

Should I place this cap before the regulator, just after the green terminal block?
 
#2,850
I use 1,000uf either side of the reg.

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#2,852
Tripmaster said:
Hi

I added a 1000uf cap after the power supply terminal block today. It worked fine for a while but has blown another walwart! :headbash:
Click to expand...

I think there is something shorted out or something wrong with your circuit, are you able to post some pictures of this setup detailed pictures of your board and other things ?

Have you tried to measure the current draw from the psu with the volume pot ?

What are the spec's of your walwarts ?

Jase
 
#2,853
jleaman said:
I think there is something shorted out or something wrong with your circuit, are you able to post some pictures of this setup detailed pictures of your board and other things ?

Have you tried to measure the current draw from the psu with the volume pot ?

What are the spec's of your walwarts ?

Jase
Click to expand...

Hi Jase

This is soooo infuriating. I don't like to give up too easily but this is starting to waste far too many power packs. I might just build one on perf board as it much easier to fault find. I find it hard to believe I've had so many problems with such a simple circuit 🙄

I'm not sure if these pictures are going to make it any easier for you...

adapter.jpg


inletandpower.jpg


LDRs.jpg


Top-7.jpg


Bottom-1.jpg


Have you tried to measure the current draw from the psu with the volume pot ? NO

Thanks for your interest!
 
#2,854
is this a switch ?

inletandpower.jpg


I don't think it's suppose to be connected that way, it should be in series not parallel, that might be the problem right there. Wire the power adapter right to the board, if you can put the meter in series on the current measuring mode and see how much current is being drawn.

Edit, infact take that whole thing out of the loop the connector and the switch and just wire the adapter to the board first.

J'
 
#2,858
Tripmaster said:
Thanks!

Can I leave the DC inlet socket as I don't have any small grommets?

Is there anything else I can measure/do to see if I have a fault?
Click to expand...

for now its not time to make it look pretty 🙂 just remove the top cover and wire the power supply right to the board. If it works then ill show you your error 🙂


( just in case ) i can see it working 100% too, it looks like your switch is wired to short your psu, 🙂

Try it wired directly to the board, remove the plug and switch, if works post back 🙂
 
#2,860
Tripmaster said:
'For now its not time to make it look pretty 🙂' Fair point 😱

All done, and hopefully not burning-out on the work bench😀

Cutting of the DC jack from an adapter has certainly widen my choice 😉

I'll keep you posted.
Click to expand...

Just remember we are just doing this to try it out, thats all. If it works then your good to next step, i can almost bet that, the switch was the problem, i see it wired in parallel not series.

Jase
 
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