# +- 15V regulator

Discussion in 'General Electronics Discussion' started by peterluke, Oct 22, 2013.

1. ### peterluke

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Oct 10, 2013
Hi Folks:

I've a 24VDC input and need to generate a +/- 15VDC for a microphone preamp circuit, just wondering what else I can use other than 7815-7915 regulator combination.

Cheers!

2. ### davennModerator

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Sep 5, 2009
for a split rail supply you generally need a centre tapped transformer to produce the 0V rail .... do you have this ?

Dave

3. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
+/- 15V works out to be 30V in total, so it's not obviously sufficient.

From the 24V you can generate +15V easily with a 7815

The negative rail needs to be generated by something that can invert the voltage.

I don't suppose you have access to -24V as well do you?

Given it's for a preamp, I suspect that the current requirement will be low. This suits something like a simple switched capacitor circuit.

4. ### davennModerator

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Sep 5, 2009
welll DOH

Thanks Harald

yeah I misread the input its supposed to be AC input

Just having a "senior moment"
I go stand in the corner

Dave

Last edited: Oct 24, 2013
5. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
How does that work with DC input Dave?

6. ### peterluke

4
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Oct 10, 2013
Hi Folks:

Thanks for the reply, the 24 VDC is for the microphone phantom power, I'm using a INA217 which requires +/- 15VDC, I could go to 48 VDC but adapter is hard to find.

Cheers!

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Aug 21, 2013
8. ### Harald KappModeratorModerator

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Nov 17, 2011
Dave, your circuit doesn't generate -15V from a positive DC input. Nor can it create +15V from a negative DC input. Your circuit would require an AC input.

Soloracer: your link points to a circuit which uses AC input (transformer). Peter only has Dc available. Therefore a means to generate the negative voltage from the positive voltage is required. Depending on current requirements, a switched capacitor circuit as suggested by Steve could be suitable. look up e.g. MAX660 or LTC1054 or Google "switched capacitor voltage inverter".