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How to get +ve and -ve voltages from the single power supply which doesn't have the functionality of +ve and -ve voltages. I have tries with the voltage divider circuits with two 10 Kilo Ohm resistor with the 10V supply because i want to have the +5V and -5V but after having this circuit the voltage fluctuating constantly.

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    \$\begingroup\$ What kind of circuit are you driving? What are the current requirements? And voltage regulation requirements? Give us some context. \$\endgroup\$ Commented Dec 15, 2016 at 15:25
  • \$\begingroup\$ voltage divider circuits with two resistors are horrible. Second thing, what is your voltage output from your power supply. Cannot help you without that.. \$\endgroup\$
    – 12Lappie
    Commented Dec 15, 2016 at 15:27
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    \$\begingroup\$ If your current demand is low enough (~10mA) and you don't need high precision, a switched capacitor voltage converter will do the job. \$\endgroup\$
    – vofa
    Commented Dec 15, 2016 at 15:30
  • \$\begingroup\$ If you were talking about driving a CMOS-opamp (e.g. TL072) based amplifier with a single 9V battery then I would say that using divider resistors can be acceptable. \$\endgroup\$ Commented Dec 15, 2016 at 15:34

3 Answers 3

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You can make a rail splitter like this: -

enter image description here

It (more or less) actively "fights" to keep the output terminal (VGND) half way between the upper and lower power rails. The problem with just using resistors is that they obey ohms law and, if you start to draw current, the voltage shifts towards one rail or the other depending on the direction of current flow.

You can also gets chips to do this such as the BUF634: -

enter image description here

It works with power rails from a couple of volts to +/-18 volts and can deliver 250 mA BUT be aware of power restrictions and heatsinking.

For lower power applications, a simple op-amp with do the job.

Depending on what current draw you want try this google search for circuit images.

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  • \$\begingroup\$ @parth do you have any questions about this answer that you wish to discuss? \$\endgroup\$
    – Andy aka
    Commented Jan 4, 2017 at 9:54
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    \$\begingroup\$ I should probably add the obligatory safety note that VGND is not earth ground. These circuits are assuming a battery, but the OP was planning on using a power supply. If you hook the ground clip of an oscilloscope probe to VGND, you will be shorting half your voltage through a device you are likely holding in your hand. I wouldn't want someone to learn this the hard way. \$\endgroup\$
    – Jestin
    Commented Nov 29, 2017 at 5:34
  • \$\begingroup\$ @Jestin good point and well made. \$\endgroup\$
    – Andy aka
    Commented Nov 29, 2017 at 12:51
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The first answer is to get another supply. Tie the + output of that supply to the ground you already have. Now the - output of this second supply is your negative supply.

If you are stuck with one DC input power voltage, then you can make a negative voltage easily yourself.

For low currents, a charge pump might be all you need. You can make one easily from a couple of transistors, diodes, and capacitors if you already have a square wave someplace. That someplace could be the clock output of a microcontroller, for example. There are also dedicated charge pump chips that you only provide the capacitors to.

For higher currents, a switching power supply with inductor is more suitable. There are chips for this too. You will have to supply the inductor, input cap, and output cap. Depending on the chip, a few other parts may be needed too.

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A dual-output supply is usually best. Assuming you want to stay with the 10V supply:

You can use a rail-splitter such as the TLE2426 to accomplish this, as an alternative to the voltage divider. Read the datasheet carefully if you go this way.

It's also possible to use an op-amp but any output capacitance needs to be decoupled lest it lead to tears and much gnashing of teeth.

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