AMZ FX ANALOG ALCHEMY GEOFX MEF ROG DIY WIKI

Power suply. Works great without the LED. With is regulator get's HOT

Started by DeusM, January 11, 2019, 07:20:43 PM

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DeusM

January 11, 2019, 07:20:43 PM
Hi guys. So I built this power supply. The problem is that when I put the LED it doesn't work at all. And the regulator get's hot pretty quick. I have no idea what could it be. I double triple checked the LED polarity. I used a 4,7k resistor in R4. I read something that changing the value of R3 I can modify the LED intensity. Can it be R3? I read that it and R1 shouldn't go up to 5K.



It's not the amps that kills you. It's the "mojo"

bluebunny

#1
January 12, 2019, 06:44:51 AM
Have you adjusted the trimmer yet to get a high-ish output voltage? I'm suspecting not: what you describe sounds like it's currently set to give a very low voltage output.  This means, 1) it's dropping a lot of volts (so the regulator gets hot), and 2) there's not enough Vf to light the LED.
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Ohm's Law - much like Coles Law, but with less cabbage...

italianguy63

#2
January 12, 2019, 06:53:41 AM
To me sounds very "short-ish" since it won't light.  Maybe check the LED polarity again.

Have you tried putting the LED "upstream" of the regulator?

MC
I used to really be with it!  That is, until they changed what "it" is.  Now, I can't find it.  And, I'm scared!  --  Homer Simpson's dad

duck_arse

#3
January 12, 2019, 08:42:46 AM
measure the voltage at the regulator "In" pin, then remove D3, and remeasure the input and output voltages. please.
You hold the small basket while I strain the gnat.

DeusM

#4
January 12, 2019, 11:35:29 AM
Quote from: duck_arse on January 12, 2019, 08:42:46 AM
measure the voltage at the regulator "In" pin, then remove D3, and remeasure the input and output voltages. please.
Why? The please? Should I be scared?  :icon_frown:
To measure it I have to put one probe on the uput or input pin and the other on the negative of the circuit?
It's not the amps that kills you. It's the "mojo"

GGBB

#5
January 12, 2019, 02:59:22 PM
Quote from: duck_arse on January 12, 2019, 08:42:46 AM
measure the voltage at the regulator "In" pin, then remove D3, and remeasure the input and output voltages. please.

Yeah - a 2.2V zener there does not seem at all right.
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DeusM

#6
January 12, 2019, 05:58:56 PM
Quote from: GGBB on January 12, 2019, 02:59:22 PM
Quote from: duck_arse on January 12, 2019, 08:42:46 AM
measure the voltage at the regulator "In" pin, then remove D3, and remeasure the input and output voltages. please.

Yeah - a 2.2V zener there does not seem at all right.
My bad. It's actually a IN4748. I just puted what I found on Multiboiard
It's not the amps that kills you. It's the "mojo"

DeusM

#7
January 12, 2019, 06:03:55 PM
This schematic doesnt have that diode. It's just for polarity protection. i don't think it shloud be a problem.

It's not the amps that kills you. It's the "mojo"

DeusM

#8
January 12, 2019, 06:45:35 PM
Ok. So only the first jack works. And the LED turns on only when there is a conection ther. Could it be that I conected the black pins togheter in the board?


It's not the amps that kills you. It's the "mojo"

DeusM

#9
January 12, 2019, 07:19:58 PM
Okay. I cut the left lug and all works great. LED turns on, but only when there is a pedal conected. Is that how its supouse to work?
It's not the amps that kills you. It's the "mojo"
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