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Zoodle 15th November 2012 01:56 AM

Simple, low noise power supply
For a first project, I built an ESP P05B (dual rail). It works nicely, but I also need a 9v single rail supply (for a condenser microphone) and 12v single rail for a phono preamp. They are to replace a battery in the first case, and a cheap 'wall wart' in the second case.

Can I use just the + side of another P05B? Or is there something even simpler that I can put together as a point-to-point? I found some designs, but I don't know enough to identify which will be best soundwise. What do you think?

gmphadte 15th November 2012 03:43 AM

Yes, u can always use the + side...

If u want low noise, look for LT series adjustable regulators by Linear Tech. U will find application circuits on their datasheet.

You can also construct a shunt regulator with discretes and will be the best.

Gajanan Phadte

tinitus 15th November 2012 10:09 PM

2 Attachment(s)
that LM317 is easy to hardwire on proto matrix board, and easy
you only need to know the adjust values to get the right voltage
but no problem
I did this a few weeks ago, first time
nothing fancy, but its a fun and easy project

btw very small print trafos doesn't cost much
and I would suggest some bigger caps after the reg(4x 1000uf maybe ?)

I would suggest two boards
one with fuse/trafo, bridge and first smoothing
and another boardwith reg and 'cap battery'

trafo away from sensitive curcuit
and reg closer

zlab 18th November 2012 01:39 AM

Hum, the suggested cap after the reg is relative small compare with the value you suggested, will it affected the response speed?

Andrew Eckhardt 18th November 2012 02:20 AM

With bigger output caps I be sure to add the output to input diode (D1, note E in the TI datasheet). This seems to ward off evil spirits. Looks like Tinitus' hand wire job has it.

metalsculptor 18th November 2012 09:05 AM

The diode is to prevent the capacitor after the regulator from driving the regulator in reverse it the main supply collapses for whatever reason.

Placing a capacitor after the reg will not affect the regulator response speed, that is set by the internals of the regulator, on the contrary it will slow the rate of load change thereby reducing the speed that the regulator has to respond to a change in load.

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