Getting 12v from a 7805 - help please!

[bacteria]

According to this site: http://www.rason.org/Projects/regulator/regulator.htm

you can get 12v from a 7805 (which normally outputs 5v).

I have tried this circuit with a 7.4v battery and a 12v battery, and I just get 5v still. In other words, it doesn't seem to work.

Ideas? I just want a simple low amperage (500mA max) step-up regulator.

I am ideally wanting to get 12v out of a 7.4v battery, other ideas?

[MrPopo]

So you've attached the two resistors and hooked up your multimeter across the final Vout pin and ground pin? One lead should be where R1 meets the regulator's Vout and the other should be on the other end of R2 (where it meets ground).

[gtmtnbiker]

So you've attached the two resistors and hooked up your multimeter across the final Vout pin and ground pin? One lead should be where R1 meets the regulator's Vout and the other should be on the other end of R2 (where it meets ground).

Ditto what MrPopo says.

[bacteria]

Actually, made a small error on the board - I get 7v out of 7.7v battery on the 7805. I need 12v (as output).

I know I can play with the resistors, however it is better if someone can give me the answer who knows what they are doing!

[MrPopo]

What's your current circuit's resistors? A 470 and a 510 should get you 12V off a 7805. Can you draw what your circuit looks like right now, including values of resistors?

[bacteria]

I'm at work at the moment so can't take pic, however I made up the 510 ohm resistor with a 460 ohm and a 46 ohm resistor; and the 460 ohm one with a small 460 ohm resistor - much smaller one than normal one.

[gtmtnbiker]

I'm at work at the moment so can't take pic, however I made up the 510 ohm resistor with a 460 ohm and a 46 ohm resistor; and the 460 ohm one with a small 460 ohm resistor - much smaller one than normal one.

Are the resistors in series or in parallel? As MrPopo said, having a picture will help. There's something you're doing wrong...

[bacteria]

Connected them in series (so: end<resistor><resistor>end), total reading was about 506 ohm as I recall.

Does it matter if using small resistors or normal ones for this?

[MrPopo]

The size of the resistor shouldn't matter much, as the power involved won't exceed their tolerance. If you can either take a photo of your setup or make a crude paint drawing it would help.

[Hobie-wan]

The size of the resistor shouldn't matter much, as the power involved won't exceed their tolerance. If you can either take a photo of your setup or make a crude paint drawing it would help.

I don't know if the message will be able to carried properly without using cunieform.