Need Help Dual Rail +/-

[TheButcher69]

I am not familiar with a dual rail power supply. I need to know how to connect a (MP1584EN DC-DC Buck Converter Adjustable Power Supply) for +6.4v - 6.00v for a Rockman X100. I was told I need to remove the 220uf caps @ C1 C2 but my board isn't marked with C1 or C2 & do I just use wire to connect + to + & - to -?

I know how to connect the 2 MP1584EN together & attached a picture & I think I'm correct attaching them to battery board which I attached pictures of. What has me most confused is there is 2 -6v as outputs so do i have to use both? I attached a picture of what I think is right.

[merlinb]

You can't use two MP1584 to generate bipolar rails from one supply. That is a non-isolated buck converter, all it can do is lower the voltage, not change its polarity. You need a switching inverter or isolating converter, at least for one rail.

[R.G.]

Merlin's right about the isolated thing. One of the converters needs to be isolating so you either need to use two converters or a single converter that has +/- outputs.
There are even more considerations you need to make. First, if you intend to feed this thing from 9V, just use a 7806 regulator to make your +6V. Then use one isolated converter to make -6V.  Or use a common, perhaps cheaper converter that makes isolated 9V to 12V and a 7906 to make your -6V.

You can find isolated +/- converters, but getting isolated +/-6V is unusual. They exist, but are either hard to find (just looked) or expensive.

There is another issue here. I'm guessing that you're not going for 9V batteries to feed this converter, so its going to be a 9V switching power supply on the input. That will have some ripple at its output at the switching frequency. Another switching converter will be running at a different switching frequency, and have a different ripple frequency. The two ripple frequencies can interact and generate a combined output ripple at the sum and difference of the two ripples. That difference frequency can be down in the audio range, and cause audible whine. Hooking two switchers together can require well-thought-out wire layout, decoupling, and additional ripple suppression on the -inputs- to the converters.

[TheButcher69]

From what I found today & what I was just told this can be done & work correctly. Here is the link https://forum.pedalpcb.com/threads/6v-power-check-my-circuit.16499/

[R.G.]

From what I found today & what I was just told this can be done & work correctly. Here is the link https://forum.pedalpcb.com/threads/6v-power-check-my-circuit.16499/

I went off and found the modules on ebay, then found a module that shows the bottom/ground plane side.
The pictures show the input (-) pin connected through a ground plane to the output (-) pin. If you connect your +9V input voltage to In(+) and In(-) then the output (-) is at the same voltage as the In(-), and Out(+) is at 6V.
Now for the top converter, the one that supposedly makes -6V. It's In(+) is tied to+9V. It's In(-) is tied to 0V on the input. It's Out(-) is also tied to In(-) by the circuit board. The Out(+) is wired to In(-), and so is its Out(-) by the circuit board itself. It's output is short circuited.
Notice also that the diagram shows -6V on both the input (-) and the output (-).

The diagram can't work if the modules are non-isolated - that is, both output + and output - have no connection to the input + and input -.

what I was just told this can be done & work correctly

On today's internet, the proper response to that is "Oh, it would be so nice if that were true."