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Oct 14, 2021, 03:37 PM
Registered User
Hmmm ...... 3.8V? Not sure how you achieved that. Does it vary if you move the little potentiometer? (disconnect LEDs first)
Perhaps get your multimeter, set it resistance reading and check if the exposed, tinned pads either side of the cut you made by the potentiometer are showing something other than zero ohms. This will confirm the cut is good. If it reads near zero then you haven't cut it through.
Next measure the resistance from the 5V pad to the adjacent 9V pad (nearest the edge of the pcb, not the long, common strip) If this reads zero you have soldered the 5V and 9V pads together. Repeat between 5V and 3.3V pad and ensure it's not reading zero ohms.

On your second attempt it is hard to see how you could have output voltage equal to input voltage. If you do nothing to the board then it should default to adjustable and you would be able to set any voltage you want. Try moving it and see if the voltage changes. I guess it's possible the control has been set hard to one end.
The device will get a bit warm mainly due to the resistance of the series control FET, the rectifier/FET and the inductor. This is one reason why working with12V strips would be better - the current reduction would be about 5/12 or less than half. Power loss is proportional to current squared so this would drop considerably.

Cheers,
David
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Oct 16, 2021, 03:59 PM
Registered User
Thread OP
Quote:
Originally Posted by KiwiDavid
Hmmm ...... 3.8V? Not sure how you achieved that. Does it vary if you move the little potentiometer? (disconnect LEDs first)
Perhaps get your multimeter, set it resistance reading and check if the exposed, tinned pads either side of the cut you made by the potentiometer are showing something other than zero ohms. This will confirm the cut is good. If it reads near zero then you haven't cut it through.
Next measure the resistance from the 5V pad to the adjacent 9V pad (nearest the edge of the pcb, not the long, common strip) If this reads zero you have soldered the 5V and 9V pads together. Repeat between 5V and 3.3V pad and ensure it's not reading zero ohms.

On your second attempt it is hard to see how you could have output voltage equal to input voltage. If you do nothing to the board then it should default to adjustable and you would be able to set any voltage you want. Try moving it and see if the voltage changes. I guess it's possible the control has been set hard to one end.
The device will get a bit warm mainly due to the resistance of the series control FET, the rectifier/FET and the inductor. This is one reason why working with12V strips would be better - the current reduction would be about 5/12 or less than half. Power loss is proportional to current squared so this would drop considerably.

Cheers,
David
I think I give up trying to do the fixed method. it's just do damn small and hard to cut in the right spot and solder a darn near microscopic bead on the pad. I decided to just roll with the one that is reading just under 4 volts since it seems to be bright enough and not heating up the battery so I know it's not pulling the full voltage. The other one I'm just gonna use the pentiometer. If I can get it to read 5v then I will just epoxy it so it can't move. Figured easier to fix the voltage that way than this soldering cutting BS. However, I found a small flat head screw driver and no matter how much I turn the pentiometer, the voltage just reads the full lipo pack voltage on the meter. How the heck do I adjust the voltage using the Pent? driving me nuts. I shoulda just gotten a fix 5v regulator and been done with it.
Oct 17, 2021, 12:35 AM
Registered User
It really shouldn't be that hard and I'm sorry to hear it's been heavy going for you. For electronics stuff this is not particularly fine work and it can be much finer.
4V is suspiciously low but if you're happy with the results then stick with it. I'm not sure I would use epoxy on the potentiometer - it's an open frame part and has a carbon track which may get upset with chemicals in the epoxy - I really don't know. I think a small bead of hot glue may be safer or just sleeve the regulator.
It's possible you got a bad part but true faults are much rarer than people make out. Hopefully you can get enough going to suit your applications.
Good luck.

Cheers,
David
Oct 17, 2021, 10:15 PM
Registered User
Thread OP
Quote:
Originally Posted by KiwiDavid
It really shouldn't be that hard and I'm sorry to hear it's been heavy going for you. For electronics stuff this is not particularly fine work and it can be much finer.
4V is suspiciously low but if you're happy with the results then stick with it. I'm not sure I would use epoxy on the potentiometer - it's an open frame part and has a carbon track which may get upset with chemicals in the epoxy - I really don't know. I think a small bead of hot glue may be safer or just sleeve the regulator.
It's possible you got a bad part but true faults are much rarer than people make out. Hopefully you can get enough going to suit your applications.
Good luck.

Cheers,
David
So today I finally got my 2nd regulator wired up with the LEDs on my other wing. Don't know why I keep getting these odd voltages but on this one it reads around 4.81 volts. I'll take it but not sure why 4.8 and not 5. Weird
Oct 18, 2021, 04:18 AM
Registered User
Getting closer.
Was that measured directly at the regulator or further down stream at the LEDs? Was this regulator set up for 5V output with the cut and the solder bridge?
You're within 5% so it may be as good as it gets. There will be a tolerance on the regulator's reference voltage and then again on the two resistors that multiply that reference up to the desired output voltage. It won't make much difference to the LEDs anyway. I think you can say you have won this round.

Cheers,
David
Oct 18, 2021, 10:17 AM
Registered User
Thread OP
Quote:
Originally Posted by KiwiDavid
Getting closer.
Was that measured directly at the regulator or further down stream at the LEDs? Was this regulator set up for 5V output with the cut and the solder bridge?
You're within 5% so it may be as good as it gets. There will be a tolerance on the regulator's reference voltage and then again on the two resistors that multiply that reference up to the desired output voltage. It won't make much difference to the LEDs anyway. I think you can say you have won this round.

Cheers,
David
I measured directly on the regulator at the output/ground pins. This is the one I did not cut anything or solder. I kept turning the pentiometer but when I was reading it before, it was just with lipo connected before I connected everything to the LED and ESC on the wing. Also, need to correct myself. It reads 4.5. plenty bright. I have a piece of extreme tape over each end of the regulator including over the pentiometer so it's not going anywhere and at least the middle where the heat sink is is exposed for cooling. Hopefully this will work out. I will know better when I actually fly it which might not be for a while since it's getting near end of flying season. Hoping I will hit some warmer and calmer days before winter.
Oct 18, 2021, 03:59 PM
Registered User
Quote:
Originally Posted by bpjacobsen
I measured directly on the regulator at the output/ground pins. This is the one I did not cut anything or solder. I kept turning the pentiometer but when I was reading it before, it was just with lipo connected before I connected everything to the LED and ESC on the wing. Also, need to correct myself. It reads 4.5. plenty bright. I have a piece of extreme tape over each end of the regulator including over the pentiometer so it's not going anywhere and at least the middle where the heat sink is is exposed for cooling. Hopefully this will work out. I will know better when I actually fly it which might not be for a while since it's getting near end of flying season. Hoping I will hit some warmer and calmer days before winter.
OK that makes sense. So it was basically a no load vs loaded reading measured at the correct place. Ideally it should be trimmed when on load but you first needed to get it in the right area before attaching LEDs.
Some regulators change modes at very low loads. For full loads they do a variable PWM but some parts do a skipping pulse operation at light loads. This may change the ripple voltage as seen by the meter.
I think you're good to go and if it's bright enough stay with it.
Heatsink? Most of the heatsinking is done by the copper pcb. Often they have plated vias to conduct heat from the chip side to the plain copper side which has a bigger area.

Cheers,
David
Oct 18, 2021, 09:11 PM
Registered User
Thread OP
Well, maybe not heat sink, but the metal box piece in the middle that gets warm. thanks for all the help. I hope to report back when I finally get to test these out in flight and see how it does overall.
Oct 19, 2021, 12:16 AM
Registered User
OK - I think you mean the inductor - basically turns of wire on a ferrite core. They have resistance so with a reasonable current flowing they do get warm.
I look forward to any user evaluation of the LEDs under low light conditions. I hope it all goes well for you.

Cheers,
David
Oct 19, 2021, 01:57 AM
Registered User
OK - I think you mean the inductor - basically turns of wire on a ferrite core. They have resistance so with a reasonable current flowing they do get warm.
I look forward to any user evaluation of the LEDs under low light conditions. I hope it all goes well for you.

Cheers,
David


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