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+5v and -15v

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Kryten

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Hi
Would it be possible to connect a +5V and +15V to make +5V and -15V

like this? Whit both regulators 78XX
 

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You cannot get minus voltage out of a regulator that has a positive voltage on the input.

Let us know what type of transformer you have and we can perform some tricks.
 
Apparently colin has never heard of switching regulators before =)
There are plenty of regulators that can provide a -15 volt supply from a positive input. Both regulators being 78XX though? No, you can't do that, they're linear regulators.
 
Of course I know about switching supplies. But he did not talk about this type of arrangement.
 
Last edited:
Hi
Would it be possible to connect a +5V and +15V to make +5V and -15V
like this? Whit both regulators 78XX


hi,
Are the +5V and +15V currently two separate power supplies.???
 
No its from the same PSU a 12V mouse kind. and im actually using LM317.

I guess i can use chargepump to make the -15V (ICL7662 is a nice one).

The ponit is that only have 12V to start with so after thinking i know that i cant use the two regs.
 
not without opening the unit and that is a lot of hassle at this time.

Other option is to use two of the powers to get +/-12V . would it then be possibel to get +5/-15V ?

Its to drive the EL on a GLCD ( I think it might be damaged anyways but i want to try it)
 
not without opening the unit and that is a lot of hassle at this time.

Other option is to use two of the powers to get +/-12V . would it then be possibel to get +5/-15V ?

Its to drive the EL on a GLCD ( I think it might be damaged anyways but i want to try it)

Do you have two power supplies on the bench.? if yes, what are their output voltages.??
 
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