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Lost with Ground, +15, -15 and 0 volts


pdirac
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Hi,

I want to know what's the difference between a reference voltage, ground and + and or - 15 volts. I'm really lost.
When I look at a schematic and see +15V and -15V and ground, the only thing I understand is that the potential
difference between +15 and - 15 volts is 30 volts.
Am i wrong ? Could someone help me out with this ???
I have a shematic of an op amp and would like to wire it but
I need help before I burn It

Thanks

Bob

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Things are easy, don't be confuzed. ;)

When you have +/-15V and ground (0V) that means that if you measure across ground and +15 you will get +15V reading and if you measure across ground and -15 you will get -15V reading if you don't move the test probe that was to the ground. These are called symmetrical voltages.

If you measure across the +15V and -15V you will get a 30V reading.

Take a look at the schematic I attach. It is a symmetrical power supply that is suitable for powering your opamp if you don't have a +/-15V PSU.

To wire the opamp, put the +/-15V at the corresponding pins and take the output related to the groung (0V) of your power supply.

You can also attach your schematic here.

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Bob, building from the schematic that Mike has provided would probably be the cheapest way to get this supply. You can purchase from surplus parts outlets. One such outlet is All Electronics. The highest cost will be the transformer. And here is an alternative:
If you do not want to make your own power supply, you might look at their wall transformers. 2 of these will give you what you need. You will want to switch the polarity of one of them to get the negative output. In other words, the tip of one and the outer barrel of the output wire on the other will be connected to ground. The other two connections will then give you + and - voltage out. Here is a link to their wall 15 volt transformers. If you are not used to working with mains voltage, then this might be a solution for you.

http://www.allelectronics.com/cgi-bin/category.cgi?category=790&item=ACTX-152&type=store

MP

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