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Gah, failed LM1117 qgain! Help?

Wolfman29

Wolfman29

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Hey peeps.

I was trying to make an LM1117 based driver for my PHR... but it won't work!

Here is an exact replica of the soldering and PCB I made for it.

lm1117failedcircuit.jpg


When I plug it into roughly 8V of input, on my testload, I get a fluctuation between 3.2A and 800mA-1A, and then it drops to zero, repeat.

It *should* be giving me roughly 113mA... but it's not! What's wrong here?!
 





your drawings just a tad bit confusing:thinking:

if you could possibly label where C1, C2, R1, and R2 are i could help
 
i think your supposed to be using the negative when using a test load..
not sure though
 
You're connecting the diode output from the wrong side of the resistor chain. It should go from ADJ side, not OUT side.

Just make your OUT+ (assuming it's diode positive) directly on ADJ. It'll magically work.

Don't mention it :)
 
Okay, so that didn't work, unfortunately. I did the same thing, except connected the adj and out right at the pins, and then stuck the resistor chain after it, and I was getting a constant current of around 360mA... I need 107mA or so from the 11Ohm resistor.... What's wrong, damnit!?!
 
Well, don't connect out and adj right at the pins.

You should connect them after the resistors, and then connect the load at the adj pin.

ETA: It looks like you have ground/- connected to the regulator +in, that would make a short circuit.
You don't need ground for the regulator.
 
What about the cap then? The caps need to go to the GND, don't they? And thanks - will try that after I take my brother to the ER :\
 
I feel like an idiot. Know why? Because I have seen that before, and I even know that the left pin is adj. I just always thought that I connect out to out =p
 
But, it works now! Woot! Just working on making it smaller now (with a file) so I can fit it in the pill.
 
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