-15 and +15 volts from automotive power for a EQ.

[george graves]

I found what seems like a nice schematic for a nice looking audio EQ.  It needs -15 and +15 volts and was designed for home use.

"With a 15V AC supply, total current draw was 92mA"

Just for some over head - I was thinking I'd like to have 250mA on tap.

http://sound.westhost.com/project84.htm



Any recommendations for getting clean +15/-15 volts from a car's noisy power?  I would lean more towards a solution using an purpose built chip rather than discrete components.  Even if that chip cost $3-$6UDS or something.

[c4757p]

Have you tried running it on a lower voltage? I bet some op amps would do this decently on +/- 6V. (TL072 needs a good amount of headroom so I'd try something different)

Of course you still have to filter the living hell out of the power, and don't forget about the occasional nasty transient, but you might not have to boost it at all.

[jeroen74]

You could consider using the LT3439.

[Psi]

You might be able to use a premade DCDC module, it's more than US$6 but does make things simple/easy.

There are many available, and i've not really searched hard, but this one will produce +/- 15V@125mA from 9-18V input
http://www.digikey.com/product-detail/en/CC3-1212DF-E/445-2472-ND/920432

I guess it depends how noise critical the 15v rails are.
You might be better with a +/-24V module and 15V linear regs on it.

[ptricks]

Max743 has dual +-12V  or +-15V outputs from a +5V source.
http://www.maximintegrated.com/datasheet/index.mvp/id/1344

The datasheet even includes the PCB pattern with parts list.
The current limit is 125ma unless you use external FET then the current is whatever you want