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krishnanice
Joined: 08 Apr 2006
Posts: 11
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 21 Sep 2006 9:03 Negative Supply! |
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| 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!
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IanP
Joined: 05 Oct 2004
Posts: 6322
Helped: 1484
Location: West Coast
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| 21 Sep 2006 10:15 Re: Negative Supply! |
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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
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newelltech
Joined: 23 Aug 2006
Posts: 217
Helped: 32
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| 21 Sep 2006 17:50 Re: Negative Supply! |
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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
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dindeds
Joined: 11 Aug 2006
Posts: 124
Helped: 8
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| 03 Oct 2006 10:05 Re: Negative Supply! |
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| 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.
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cydi
Joined: 12 Dec 2006
Posts: 166
Helped: 11
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| 18 Dec 2006 7:52 Negative Supply! |
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| 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.
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AlexNadal
Joined: 28 Nov 2006
Posts: 25
Helped: 1
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| 16 Jan 2007 11:34 Re: Negative Supply! |
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| Other way is to use an LM7909, that provides you a -9 voltage and a LM7809 that provides you a 9 voltage
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kender
Joined: 19 Jun 2005
Posts: 931
Helped: 68
Location: Stanford, SF Bay Peninsula, California, Earth, Solar System, Milky Way
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| 06 Mar 2007 8:30 Negative Supply! |
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| 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.
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muralicrl
Joined: 06 Feb 2008
Posts: 281
Helped: 30
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| 13 Mar 2008 11:39 Re: Negative Supply! |
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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
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