same transformer, different voltages?

calx44 · 25th September 2012, 07:07 PM

Hi,
I had a post on here not so long ago about making a guitar amp. I have a preamp schematic that runs off 15 volts and a power amp chip that works best off about 25V. Can i use the same transformer/power supply? If so how?
Really basic question i know...

Thanks in advance
Callum

sreten · 07:47 PM

Hi,

You tap off and regulate the high current 25V rails down to 15V
for the low current supplies for the preamp, leaving the 25V rails
directly connected to the power amplifier.

rgds, sreten.

Assuming you don't use a multitapped transformer ...

calx44 · 27th September 2012, 06:11 AM

OK, thaks for that. Makes sense really when I think about it.
Cheers
Callum

calx44 · 1st October 2012, 06:49 PM

I should have asked this before really, but how can i do this? with a voltage divider?
Thanks
Callum

sreten · 1st October 2012, 07:44 PM

Hi,

Zener diodes or regulators, you can't use a voltage divider for power
supplies. Look up some schematics of amplifiers to see how its done.

rgds, sreten.

calx44 · 2nd October 2012, 04:38 PM

Thanks. I have never really done anything with power supplies before, but I thought a divider wouldnt really work.
Cheers
Callum

Minion · 7th October 2012, 04:49 PM

Depending on yer preamp you might be able to run it off of 25v.
If it is an opamp preamp and runs off a single supply you can most likely run it off of 25v , most opamps can run off of 30v or more and you will get increased headroom useing a higher voltage supply.

Cheers

Maybe post a schematic of your preamp design.

25th September 2012, 07:07 PM	#1
calx44 diyAudio Member Join Date: May 2012	same transformer, different voltages? Hi, I had a post on here not so long ago about making a guitar amp. I have a preamp schematic that runs off 15 volts and a power amp chip that works best off about 25V. Can i use the same transformer/power supply? If so how? Really basic question i know... Thanks in advance Callum

25th September 2012, 07:38 PM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, You tap off and regulate the high current 25V rails down to 15V for the low current supplies for the preamp, leaving the 25V rails directly connected to the power amplifier. rgds, sreten. Assuming you don't use a multitapped transformer ... __________________ There is nothing so practical as a really good theory - Ludwig Boltzmann When your only tool is a hammer, every problem looks like a nail - Abraham Maslow Last edited by sreten; 25th September 2012 at 07:47 PM.

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27th September 2012, 06:11 AM	#3
calx44 diyAudio Member Join Date: May 2012	OK, thaks for that. Makes sense really when I think about it. Cheers Callum

1st October 2012, 06:49 PM	#4
calx44 diyAudio Member Join Date: May 2012	I should have asked this before really, but how can i do this? with a voltage divider? Thanks Callum

2nd October 2012, 04:38 PM	#6
calx44 diyAudio Member Join Date: May 2012	Thanks. I have never really done anything with power supplies before, but I thought a divider wouldnt really work. Cheers Callum

7th October 2012, 04:49 PM	#7
Minion diyAudio Member Join Date: May 2006	Depending on yer preamp you might be able to run it off of 25v. If it is an opamp preamp and runs off a single supply you can most likely run it off of 25v , most opamps can run off of 30v or more and you will get increased headroom useing a higher voltage supply. Cheers Maybe post a schematic of your preamp design.