Simple 12v adjustable help

[MarianB]

Well i think it is you that needs to read much more carefully my messages, just because someone doesn't like some of your sugestion it does not give you any reason to be upset, and by no means does it gives you the right to attack them, as i sayd you are stuck on useless semantics, even you understud what i meant but you are maybe too stubborn to admit it.

Well, if that is what you are then, good luck, you'l need it.

 

[liamstears]

I just came across this circuit here (scroll down to Simple Adjustable Voltage Source):

Telephone In-Use Relay, LM317 Regulators, Lithium Charger

And this sounds perfect

Now my questions are, how many amps could this simple npn pnp circuit provide? Also just how much heat will it produce?

I only have the small clip on heatsinks that I can put on it although I could possible place it on the larger heatsink in the power supply and possibly even next to the slow running 80mm intake fan if needed?

I think I will go this route as it's simple and cheap just need to know how many amps I can get in this circuit and how well I need to cool it

If possible I would like to be able to supply up to 5a so if different parts are needed in this same circuit please do let me know although I could live with 2a output

So is my attached picture right before I wire it up?

 

[tauro0221]

Hi,
I do not know really what you want to accomplish. You are changing constantly your design and you will not accomplish anything. Stick to one design and see if you can make it work. I never had a problem using linear voltage regulators and I see that you can not get none to worked. If you follow to the letter the datasheet or used one of the samples schematic in the datasheet you will not have a problem. If you want 5 amps output my advice it is to use the LM338. It will output 5 amps with a good heat sink. If you use the LM317 max amp output will be 1.5. and you must have to bypass it with a transistor to be able to output more than 1.5 amps. Get the LM338 follow one of the examples that meet your specification in the datasheet and as long you follow the schematic you will not have any problems. Give it try.
Good luck.