Agilent E3646 Power Supply with Opamps (for dual rail power)?

[spiff72]

I am trying to teach myself a few basics and have added a an Agilent E3646 to my bench.

I am trying to use it to power an opamp with a +/- power supply.  My thought was to set the PSU to tracking mode, link the two outputs in series, and use the jumper connecting one supply to the other as a virtual ground point.  Crude schematic attached.

First, is there anything "wrong" with this approach?

Second, I am a bit confused about what the output would reference to (say if I was driving a small load with the output)?  What "Ground" would I connect the load to?

Thanks!

[David Hess]

First, is there anything "wrong" with this approach?

That is what a floating dual output power supply is designed for and how to do it.

Second, I am a bit confused about what the output would reference to (say if I was driving a small load with the output)?  What "Ground" would I connect the load to?

Say "common" instead of "ground".  A load could be referenced to positive, negative, or common depending on the application.  Most often the load is referenced to common.

Ground is a separate connection which can go to any of the output terminals but is typically not needed.  The E3646A provides this connection on the back but many power supplies include it on the front as the green or white terminal.  When a grounded instrument like an oscilloscope is hooked up to your test circuit, it provides earth ground.  Using a floating power supply avoids some problems with ground loops.

[spiff72]

First, is there anything "wrong" with this approach?

That is what a floating dual output power supply is designed for and how to do it.

Second, I am a bit confused about what the output would reference to (say if I was driving a small load with the output)?  What "Ground" would I connect the load to?

Say "common" instead of "ground".  A load could be referenced to positive, negative, or common depending on the application.  Most often the load is referenced to common.

Ground is a separate connection which can go to any of the output terminals but is typically not needed.  The E3646A provides this connection on the back but many power supplies include it on the front as the green or white terminal.  When a grounded instrument like an oscilloscope is hooked up to your test circuit, it provides earth ground.  Using a floating power supply avoids some problems with ground loops.

Thanks for the reply!

In my haste to find a bench supply, I really wanted to find a triple output that had a common port on the front, plus a + and - rail, but I got this Agilent at a good price and it was in great shape.  I have another high power DPS5015 as a third source (powered by a server PSU).

So lets say I was just playing around with this circuit as a simple audio amp.  Would I connect the output of the opamp to the + terminal of a speaker and the negative to the point marked as "X"?

[David Hess]

In my haste to find a bench supply, I really wanted to find a triple output that had a common port on the front, plus a + and - rail, but I got this Agilent at a good price and it was in great shape.  I have another high power DPS5015 as a third source (powered by a server PSU).

The dual tracking power supplies I commonly use are configured like that with a separate fixed +5 volt output which actually is tied to ground.

So lets say I was just playing around with this circuit as a simple audio amp.  Would I connect the output of the opamp to the + terminal of a speaker and the negative to the point marked as "X"?

Audio amplifiers with bipolar supplies return the other side of the speaker to common unless a bridged configuration is used.

[spiff72]

In my haste to find a bench supply, I really wanted to find a triple output that had a common port on the front, plus a + and - rail, but I got this Agilent at a good price and it was in great shape.  I have another high power DPS5015 as a third source (powered by a server PSU).

The dual tracking power supplies I commonly use are configured like that with a separate fixed +5 volt output which actually is tied to ground.

So lets say I was just playing around with this circuit as a simple audio amp.  Would I connect the output of the opamp to the + terminal of a speaker and the negative to the point marked as "X"?

Audio amplifiers with bipolar supplies return the other side of the speaker to common unless a bridged configuration is used.

This was the model I had been trying to land:
https://www.ebay.com/itm/Agilent-E3631A-Triple-Output-DC-Power-Supply-6V-5A-amp-25V-1A-/401763761100?redirect=mobile&nma=true&si=dkR3AcSXwIxsOc2Gd3jstkgXLao%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

But they would jump into the mid 250 price range in the last 30 seconds. I threw out a flyer bid on the model I have and won, not really expecting that to happen. I have been pleased with it so far.

I did run the opamp with the circuit drawn out and played with various components and input signals. So really it does exactly what I need for about $100 less than the triple output.