Charge Pump with 15 regulator... HOT

Started by goldenmonkeycolor, February 27, 2015, 06:13:39 PM

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goldenmonkeycolor

I built a charge pump on vero (utilizing a layout I cannot find at tagboard effects, because of the way its listed, but i know ive used it for 9v to 18v succesfully many times)

anyways Its getting hot!!! the regulator gets super duper hot- its putting out 14.9v on my meter and appears to be working, but man it cooks- i havent let it go too long as I didnt wanna cook it completely.
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I just added the regulator to a vero layout.  took the 18v output to the lm7815ac (to-92 package) input, ground to the ground and output to its own pad.  I also added one 10uf capacitor from output to ground

I also originally installed 1n4004 diodes thinking they were shotckky diodes all this time (i do not know my diodes.... hm... among other things)  maybe i fried the lm78l15 before I iswapped them for 1n5817's. did i mess something up?  i just looked at the datasheet and it says the minimum voltage input is 16.7v- could i have fried it by using the 1n4004's (where it only output 12v when I measured)

When looking at the regulator laying flat with legs facing you and flat side facing down- i installed it as input on the right leg, ground center and output left leg.

greaser_au

#1
I assume you mean a LM78L15AC is what you are using?
When the output voltage is 14.9V, what is the input voltage?  
Is there any load on the output of the regulator?
Low input voltage should not hurt.
Connecting the device in reverse (any situation where Vin is less than Vout) will likely destroy the regulator.
What type of 10uF output cap did you use? if an aluminium electro, good practice is to parallel it with a 100nF  ceramic/monolithic.

Try to find the correct manufacturer's datasheet. The random (planeta) datasheet I found online (assuming I'm reading it correctly) says input left/output right when orienting it as per your description - different manufacturers represent the same things in different ways - it can get confusing. Over the years I've seen to-92s pinouts drawn front-on, one time even rear-on  (whats with that???), bottom view, top view, and a couple of different obliques.  Some name the terminals directly on the drawing, others use their standard case drawing with pin numbers and provide a pinout table (sometimes well separated from the drawing  >:( )...  

good luck
david