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'[EE]: quick'n'dirty positive to negative convertor'
2002\02\06@111703 by John Walshe

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Hi guys'n'gals,
   Has anyone got any neat ideas on how to a +5v to -5V converter for a
power supply. Only a few milliamps required on each rail. It's a once off
for something I'm trying at home. I did try just splitting the supply but
for some reason the positive circuit didn't like it (it wouldn't work!).
I must invest in a dual rail PSU sometime!
Any thoughts appreciated,
John

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2002\02\06@112357 by Spehro Pefhany

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At 04:09 PM 2/6/02 +0000, you wrote:
>Hi guys'n'gals,
>     Has anyone got any neat ideas on how to a +5v to -5V converter for a
>power supply. Only a few milliamps required on each rail. It's a once off
>for something I'm trying at home. I did try just splitting the supply but
>for some reason the positive circuit didn't like it (it wouldn't work!).
>I must invest in a dual rail PSU sometime!
>Any thoughts appreciated,
>John


Easiest thing is to slap an ICL7660 and a couple of caps in there.
http://pdfserv.maxim-ic.com/arpdf/ICL7660-MAX1044.pdf

If -3V is ok you can use a hex inverter as an oscillator and a charge pump
using a dual diode, and save a few pennies. Or feed it a reasonable clock
signal that you may have on the board elsewhere.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
spam_OUTspeffTakeThisOuTspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
9/11 United we Stand

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2002\02\06@114314 by Peter Onion

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On 06-Feb-02 John Walshe wrote:
> Hi guys'n'gals,
>     Has anyone got any neat ideas on how to a +5v to -5V converter for a
> power supply. Only a few milliamps required on each rail. It's a once off
> for something I'm trying at home. I did try just splitting the supply but
> for some reason the positive circuit didn't like it (it wouldn't work!).
> I must invest in a dual rail PSU sometime!
> Any thoughts appreciated,
> John

Charge Pump !

generate a square wave signal 0 to +5v

Put it throught a capacitor  (say 1uF)

Connect other end of capacitor to a diode which has it's cathode connected to
0V.  You will get -4.4v  (5v - diode drop) on the capacitor.

Or get a charge pump IC which does it all for you (MAXIM do such devices, but
I've never used any so I can't recomend a particular device).


Hope this helps.

Peter

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2002\02\06@115252 by SM Ling

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>     Has anyone got any neat ideas on how to a +5v to -5V converter for a
> power supply. Only a few milliamps required on each rail. It's a once off
> for something I'm trying at home. I did try just splitting the supply but
> for some reason the positive circuit didn't like it (it wouldn't work!).
> I must invest in a dual rail PSU sometime!

Or get a ATX PC power supply as a spare and it can also acts as your
bench-top supply.  If you do a little modification, you can have adjustable
output too.

Cheers, ling SM

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2002\02\06@115818 by denis

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Hi,

See to Analog Device.

ADM660
products.analog.com/products/info.asp?product=ADM660
Work to 1.7 to 7 volt,

Regard

Denis

{Original Message removed}

2002\02\06@124426 by Kirk Lovewell

picon face
Try Telecom Semi (now owned by everyones favorite
microcontroller manufacturer)
p/n: TCM828.
I used on a recent design and it has performed well.

Kirk

>
> Hi guys'n'gals,
>     Has anyone got any neat ideas on how to a +5v to
-5V
> converter for a
> power supply. Only a few milliamps required on each
rail.
> It's a once off
> for something I'm trying at home. I did try just
splitting
> the supply but
> for some reason the positive circuit didn't like it
(it
> wouldn't work!).
> I must invest in a dual rail PSU sometime!
> Any thoughts appreciated,
> John
>
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> http://www.piclist.com hint: PICList Posts must
start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other
[BUY]:,[AD]: ->Ads
>


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2002\02\06@144909 by Kirk Lovewell

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Sorry, I think that should be Telcom Semi, not
Telecom.  At any rate, you can find them at
http://www.microchip.com now.

Kirk

{Quote hidden}

to
> -5V
> > converter for a
> > power supply. Only a few milliamps required on
each
> rail.

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2002\02\06@150209 by Alvaro Deibe Diaz

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What about a ubicuous MAX232? Sure, you have one on the desk. To low the
-10V to -5 you can use 3 LED in series...

This is as quick and dirty as it could be, isnt't it?

Only a few mA, though...

Regards,

Alvaro Deibe

{Original Message removed}

2002\02\07@042803 by uter van ooijen & floortje hanneman

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>     Has anyone got any neat ideas on how to a +5v to -5V converter for a
> power supply. Only a few milliamps required on each rail. It's a once off
> for something I'm trying at home. I did try just splitting the supply but
> for some reason the positive circuit didn't like it (it wouldn't work!).
> I must invest in a dual rail PSU sometime!
> Any thoughts appreciated,

max232 + 7905?

Wouter van Ooijen

Van Ooijen Technische Informatica: http://www.voti.nl
Jal compiler for PIC uC's:  http://www.voti.nl/jal
PICs kopen? http://www.voti.nl/shop

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