# Does an amplifier have a max gain ?

Discussion in 'The Projects Forum' started by simeonz11, Jan 8, 2010.

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1. ### simeonz11 Thread Starter Active Member

Apr 29, 2008
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For this current project of mine , I need to amplify an ac sine wave +-0.5v(1vp-p) . It is a pure sine wave by all means and perfectly symetric + and - etc ... I wont be dealing with anything but a pure sine in the audio range .

I wish to amplify this to a maximum of +-24 volts . The opa604 .

http://focus.ti.com/paramsearch/doc...null&appId=null&viewDeviceCallingPage=null#rt

Now I have located an op amp that seems to suit my needs , my question is the following .

Can a 50 or 100x gain of such a small signal be amplified precisely at +-24 volts with a single op amp , or do I need 2 x op amps .

Does open loop gain mean max gain of an amplifier , all datasheets have a max open loop gain and a minimum gain , but there is no talk of maximum gain in closed loop .

Also , if this op amp is specified for +-24 volts , will it do harm if I use 2 x brand new 12v batteries , I know these can reach 13.8 volts when new , so +- 27.6

thx .

Last edited: Jan 8, 2010

Apr 20, 2004
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3. ### SgtWookie Expert

Jul 17, 2007
22,183
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OK, wait a minute...

Do you mean one battery for a Vcc of 13v and another for a Vee of -13v giving a total 26v?
Or do you mean you're using four batteries; two for a Vcc of +26v and two for a Vee of -26v?

And what kind of output current are you expecting to get out of this amplifier?

4. ### t06afre AAC Fanatic!

May 11, 2009
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You will most most probably damage your your circuit if the power rails exceed 25 volt. From the data sheet we can also read that then the power supply is +/-15 volt the highest output voltage will be somewhere between 11 and 12 volt (+/-) with a 600 ohm load. If you use a +/- 24 volt power supply the output voltage will be around 20 volt maximum. But this will depend somewhat on the load. Anyway you will never get +/- 24 volt output swing with this circuit.

Apr 20, 2004
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