Im abit confuse how to i connect my supply to my opamp Vcc.
Should i do it by method a) or b). The last time i used the opamp i happen to fry it due to wrong Vcc wiring. I must get it right this time

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I assume you are using the 741 op amp. Well, both are wrong. The 741 is a dual supply opamp. If you are using 15V supplies, you'll need 2 of them.
Opamp V+ is connected to the +VE of Supply1.
Opamp V- is connected to the -VE of Supply2.
-VE of Supply 1 is connected to +VE of Supply2.

Hope you get the idea.

 

Is this correct then?

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Hi Fabbie,
The polarities of your supplies are correct now, but I don't think an old 741 opamp will work with only 10V across it. Use a more modern opamp that can work with either a single supply of 3V to 44V, or dual supplies of 1.5V to 22V.

 

Don't forget the common point of the 2 supplies will be your GND reference for the opamp

 

Is correct.
A 741 op amp will work on a sngle polarity 9V supply depending on it's use. All that is necessary is to bias one input to 1/2 the Vcc voltage with
a voltage divider.

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10V cant work across a 741 opamp? The datasheet stated that the maximum Vcc is 15V. I better test it out first to see it with my own eyes first

 

Hi Fabbie,
I said that I didn't think that a 741 will work with 10V across it, which is dual 5V supplies like you show.
It is rated for use only with dual 15V supplies where its output has a voltage loss of up to 5V positive and 5V negative when driving a load resistance of 2K or less. With dual 5V supplies its output might not have any output voltage swing whatsoever.
Its input common mode range has a limit of 3V from each supply, so with dual 5V supplies might have an input voltage swing of only positive 2V and negative 2V, which isn't much.
You could test one and it may work or not. You could test ten and some might work and others not. If you want them all to work then select an opamp that is designed for your low-supply-voltage application.

 

Alright, THX audioguru. I'll keep that in mind.
I tested the 741 by applying a non-inverting opamp with a DC input of 1.5V and gain of 2. I used 5V and -5V for my Vcc and i achieved good results which was 3V.

Better be safe than sorry

 

Hi Fabbie,
What did your test use for the 741 opamp's load? Your 10M meter?
Try loading it with 2K and see what its output does.

 

just a small suggestion if you want to upgrade your op-amp design goto
www.ti.com it's the texas instruments website, once there look up a OPA2134 these are precision op-amps that come in single dual and quadruple packages. These things work insanely better than a 741. The neat part is that you can overnight samples for free, i did this lots of time when I tried to build my guitar pre-amp. There's a max to how many you can order but it's better than paying $100 for a thousand.

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I just wan to confirm this.
If i input +5V into my +Vcc and GND my -Vcc, it wouldnt change my maximum opamp output, right? The only difference would be the opamp wont be able to output out any negative voltage, right?
My opamp purpose is only to generate a positive output, therefore, i might no need a -5V into my -Vcc.