Negative voltage generator

[Thane of Cawdor]

Hi,

I've been searching for a way to generate smooth negative voltage for my op amp circuit so I can run it off a single supply. What is the simplest way to do this?

P.S. I've already tried 555 circuits and I don't really want to buy specialised inverter IC's for this project.


Thanks

[Rerouter]

if your playing with a 555 just rectify the output of the crude inverter and throw it through a linear negative regulator, (7905?)

[Thane of Cawdor]

if your playing with a 555 just rectify the output of the crude inverter and throw it through a linear negative regulator, (7905?)

Ok, will try to build it now 

[uwezi]

P.S. I've already tried 555 circuits and I don't really want to buy specialised inverter IC's for this project.

Still I would suggest you look into the MC34063. It probably needs fewer external components than any 555 circuit, is very cheap and easy to use. Just enter your values on this webcalculator. The schematic diagram on the page will automatically adjust to up-converter/down-converter/negative-output. See the screenshot below as an example.

But be careful when using this chip for the first time! For some weird reason it is the only chip I know where everyone uses the pinout as seen from below!

[Thane of Cawdor]

Hi,


Couldn't I just use a simple MAX232's positive and negative voltage generator?

Thanks

[fcb]

I've used the ICL7660A in a few audio designs - painless and if you've got enough capacitance on the -ve rail - very low noise.

[Thane of Cawdor]

I've used the ICL7660A in a few audio designs - painless and if you've got enough capacitance on the -ve rail - very low noise.

Would you know how much current it could supply?

Thanks

[BravoV]

Alternative cheaper non IC method using only discrete components, read it carefully here on the circuit design starting the one posted by Jay_Diddy_B and also few variants below it -> Starting from this post and go forward.

Hope this helps.

[Bored@Work]

eBay auction: #141047197560 $1.41
eBay auction: #380755874794 $1.44

Can easily be wired up to generate a negative voltage.

[I_may_be_drunk_right_now]

Hi,

I've been searching for a way to generate smooth negative voltage for my op amp circuit so I can run it off a single supply. What is the simplest way to do this?

P.S. I've already tried 555 circuits and I don't really want to buy specialised inverter IC's for this project.


Thanks

You can't get away with biasing at 1/2Vcc? Is this a DC application? What is this "circuit"? Is it a secret? Tell us so we can give better answers, otherwise it's just pissing in the wind when after 235 replies you finally tell us what you really want.

[TerminalJack505]

Did you try something like the attached with the 555? 

It should work fine so long as you don't need a lot of current or a regulated voltage.

[johnwill]

basically there are two ways to generate negatives volatges from a positive source . A switching power supply with transformer or coil ..
depending on your power requirements .. it can be as easy as a transistor and a coil. The second possibility is a "CHARGE PUMP " is basically an analog switch commuting the poles of a capacitor .. poe A is connected to positive source .. pole B is grounded .. is charged in time T depending of the cap capacity . Next cycle capacitor is completly disconnected from source and pole A is grounded pole B is connected to LOAD .. The best configuration is to have two caps while one gets charged by the source the other powers the load.

[kg4arn]

If you don't need too much current...