Switching a single supply op amp circuit to dual supply

[Olivolts]

I have little experience with op amps , but having built a Yamaha NE-1 that works ok I'd like to change the 9 volt battery input which has a voltage-divided ref voltage to a dual rail input , so I can box it with another circuit that is dual rail .
Any pointers on how to do this much appreciated.

[r080]

Welcome to the forum! One neat trick here is to use google to search the site, like this:

site:diystompboxes.com single to dual supply

There was a relatively recent thread on your topic:

https://www.diystompboxes.com/smfforum/index.php?topic=125851.0

However, most of the search results are to convert dual supply to single supply. If it were me, I would simply use the positive 9V from your supply (referenced to "ground"), since you already have a design that works.

[ElectricDruid]

In general, this can get a bit tricky despite the principles being simple, but for this example it's straightforward:

1) Chuck away the 39K,47K and 10u that create the split "B+" supply.
2) Attach B+ to your bipolar Ground
3) Attach the original ground of the power supply section to bipolar -V
4) The three ground connections on the audio (upper) section of the schematic can be connected to the new bipolar ground.
5) Attach +V to the bipolar +V

Done!

There's probably some tidying up that could be done, since bipolar powered circuits tend to need less DC blocking caps and so on than single-supply circuits where everything is carrying a 4.5V bias around with it. I'd have to re-draw the schematic to know for sure.

HTH

[antonis]

What Tom said...

[marcelomd]

What Tom said...

The power supply looks triple shorted. +V, -V and gnd tied together on the lower left?

[antonis]

Just a rough scheme to indicate GND as +/- V midpoint, Marcelo..

Do you prefer something like this?:

[ElectricDruid]

After Antonis' post, I notice that actually all the ground connections on the upper audio section of the schematic are capacitively separated from DC anyway, so whether they go to the -V or to Ground (as I suggested) is pretty much irrelevant. It should work either way.

[antonis]

IMHO Tom, as long as 10μF cap is set between +V & -V, it's better for audio connections to go to GND..
(less garbage from power supply..)

[Olivolts]

Thanks for all the replies , I feel confident I can sort it out using this information ,,, and apologies r080 for not using the searchbox , google had given me so many dual-to-single that I'd given up hope .

[antonis]

so I can box it with another circuit that is dual rail.

Just realized OP as newcomer..
Delayed Welcome  and a comment about electro caps voltage rating..

10μF one (between +V & -V) should be rated higher than power supply magnitude..
e.g. for +/- 9V = 18V, 25V rating should be fine - for +/- 18V (marginal for IC supply), 50V should be fine..

For the other two 10μF caps, slightly higher than half power supply magnitude should also be fine..

Of course, you can always use 3 identical caps for bill of materials simplicity..

[amptramp]

The 10 µF output cap that goes through a 1 K resistor to the level control will now see both positive and negative voltage.  I used a 10 µF non-polar cap in a similar design using ±5 VDC supplies.  If you don't have a non-polar cap, a pair of 22 µF connected back-to-back will do as the resulting capacitance will be 11 µF and 22 µF is the nearest standard value.