7805 regulator question

[asnider123]

I have come upon a bunch of 7805 pulls from motherboards. They are rated 5V @1.5 amps. This is not sufficient for a 5v mod. Question .. can you run 2 ICs in parallel for 3A total (like batteries in parallel) or will one IC take dominance of the circuit? Or is the rating a conservative number and it could really provide 5V @2 amps?

 

[drewk302]

It can be done, I read this: (it may give you a starting point) High Current Voltage Regulation - Electric Circuit

 

[phoenixfire]

Yes, you can use regulators in parallel to increase current, each one will put out 5v at it's rated current. I don't know why I didn't think of this when the regulator quit on my 5v, box DUH! Contrary to popular belief a single 7805 will do a passable job on a 5v box mod in a pinch. I have been using one from ratshack on mine for about 3 weeks and am quite happy with it. I use 2 ohm cartos mainly and it has been putting out nice vapor and keeping me going. This allows me to loan out my egos to my wife and new vapors to get them off analogs until they can get one of there own.

 

[breaktru]

Yes Alan you can split the amperage load but you will be draining twice as much from the battery, although it's milliamps is twice the drain.
It's not so bad if your using high mah batteries.

 

[drewk302]

keep us up to date if you do it. It would be cool to see how it holds up, and specs and so on for all informational purposes.

 

[Dalton63841]

I made a box mod last night using 2x 14500 in series and a 7805 regulator from RS, and it works GREAT so far, doesn't seem to get hot at all unless I chain vape on it.

I didn't even use any resistors or anything. I used this schematic that I found on instructables.com

Obviously my batts would be in place of the 9v, and the atty connector in place of the usb. I know its not the best way to do it, but in a pinch with no other parts available, it works great.

 

[asnider123]

Dalton .. that's cool! Simple, made from readily-available parts, perfect.

The 7805 is rated at only 1-1.5 amp .. just wondering what atty resistance you are using.

 

[Dalton63841]

Dalton .. that's cool! Simple, made from readily-available parts, perfect.

The 7805 is rated at only 1-1.5 amp .. just wondering what atty resistance you are using.

I knew the 7805 I had was only rated at 1amp, but figured I'd give it a shot on the premise that it would be okay since it is only doing work intermittently. So far it is still working great.

At the moment the only HV atties I have are these. Not sure what resistance they are exactly as I don't currently have a way to measure it, but the atties are made for 6v mods according to the website. I bought them just to test out a VV mod, which I don't have parts for yet.

My guess is about 3.2-3.5ohm. At 5 volts my math shows ~1.5amp.

 

[asnider123]

Those look neat, it's odd that they do not tell you the resistance ???

 

[Dalton63841]

Those look neat, it's odd that they do not tell you the resistance ???

After I bought them I found several complaints that they don't last, but they are doing fine for me. I am very curious about the resistance myself. I feel very ghetto flying blind doing these mods. I really can't wait till next month(playing catchup on bills this month) so I can get a new multimeter and a few other things. The 4 mods I have built so far were done with scrap pieces in my trunk, and the tools I have used are a steak knife and $5 solder iron.