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FrozenGate by Avery

LM1117 Driver Question?

Joined
Jan 14, 2011
Messages
3,816
Points
63
Hey there, everyone. I recently got my parts from Mouser and DigiKey and I have been working on a micro, Aixiz-sized driver for a couple of hours now.

For some reason though, even though it's all wired up and it *should* work, my test-load reads about 353mV => 353mA, but I am using a 3.3Ohm resistor and I get the same reading when I use a 10Ohm resistor! Why isn't it working?

Anyway, here is how my board is set up (it is all on a 3x7 through-hole board... imagine 3 holes by 7 holes and it should make sense).

circuit.jpg


So why won't it work? What's wrong with it?

Is something wrong with the LM1117?
 





How many diodes are in your test load, what is your supply voltage, and what is the power rating of your resistor?
 
I have the Rkcstr driver (which is switchable between 4 and 6 1N4001s), and I just stuck a little 1/4W SMD resistor on the pads, but it didn't start smoking or anything when I connected the testload.

My supply voltage was slightly lower than 6V, probably around 5.8V. But, I set it up to be using the "red" diode setting, and it still read the same.
 
Mm - I discovered something else.

When I disconnected the resistor from my test-load, and I hooked up my driver with a 10Ohm resistor on it, and then I put my DMM on ammeter and measured the amperage across the area where the resistor used to be, I get about 350mA, and then after about 2 seconds it drops to 124mA. Doesn't that sound right? 1.25V drop from the driver, so 10 Ohms = 125mA, correct?

Anyway, is that an accurate way to measure the output of some drivers (or at least mine)? And why did I get that boost of 350mA at the beginning? Cap discharge?
 


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