How to provide negative supply to an amplifier?

[krishnanice]

Hey all, I'm using couple of op-amplifiers in my design and I have to provide +9V and -9v supply to both the amplifiers. As of now, for the whole system I'm using a single supply of +9V battery as the supply. I'm not sure of how to provide -9V to the op-amp. Do I just have to switch the batterys? I would appreciate if someone could actually help me! Thank You!

 

[IanP]

negative supply

The easy way is to use 2 x 9V batteries, but if you need to operate of one you can build a dc-dc converter ..
Below is one example .. instead of 5V zener diode use 9V ..
In fact the output voltage will be higher than -9V .. something like -8V, but it shouldn't matter much for the operation of opapms ..

Regards,
IanP

 

[newelltech]

charge pump negative supply

As an alternative to the 555 you might want to search for dc-dc converter IC's. I think there are some low-current chips that only require an external capacitor.
If you're processing ac signals, you could keep using a 9 V supply and bias the ac at 4.5 V, thus eliminating the need for another power supply.
Also you might want to find a different amplifier that works with a single supply - there are lots of them

 

[dindeds]

external negative supply

If you don't need output swing from + to - supply then wire the op-amp in single ended configuration. Then you can use single 9V battery.

 

[cydi]

charge pump dc dc converter negative supply

If you have a couple of +9V batteries. its pretty simple to get the -9V. Just cross couple the two get the +9V, common, and -9V.

 

[AlexNadal]

battery negative supply

Other way is to use an LM7909, that provides you a -9 voltage and a LM7809 that provides you a 9 voltage

 

[kender]

simple negative supply

If you don't need a lot of current on the negative supply rail, use a charge pump voltage inverter. For example, the venerable TC7660.

 

[muralicrl]

-1.3v negative supply

Hi,

In your power supply, three terminals will be there. -ve, Gnd and +ve

To give -9V use -ve and Gnd terminals.
To give +9V use +ve and Gnd terminals.


If you need more details, contact me.

Regards,

N. Muralidhara

CRL-BEL