9v Highly regulated/clean PS for guitar fx

sjaltenb · 13th November 2008, 09:23 PM

Hello everyone, this is my first post on this forum. Looks to be a great forum that I can add to my list!

For almost a year now I have been working on a multi guitar FX pedalboard similar to those built by Pete Cornish for David Gilmour of Pink Floyd.

The board is comprised of a wooden enclosure housing around a dozen FX units. All but 3 are powered by 9vDC, most of which only pull about 5-20ma.

Two of them are AC powered tube units, requiring 24vct'd ac and 12vac both at 200ma. The third is about 50ma at 15vac with an onboard regulator.

I have a custom built tranformer arriving which has about 14 secondaries. (AC120 primaries). Except for those 3 FX units that require AC input, each secondary is rated at 12v 100ma (two are 200ma)

I want to build a VERY VERY clean noise free highly regulated power supply for each individual secondary and therefore each FX board gets its own independent power to reduce ground loops etc.

I am new to power supply design, but understand the basics. I want to to be VERY clean but I do not want to use something as complex as the Super Regulated supply i found on this board earlier. I saw in pictures that Pete Cornish uses extremely large (at least 10,000uf) filter caps directly after the bridge rectifier so I plan on doing this if possible with my transformer specs.

My questions are: with the 7809, and the 12vac power supply at 100ma (remember only about 20ma needed) How large can/should I go with the Filter cap and then what other features should I include to make it a very good power supply? I will post pictures of my board and an idea for a schematic I have so far.

Thank you! Sorry for the lengthy post!!

sjaltenb · 13th November 2008, 10:39 PM

the inside is sprayed with EMF shielding paint... a lot of progress has been made since these pics but you get the general idea...

gmphadte · 21st November 2008, 05:00 AM

If u need clean power supply, then 7809 will not do.
At least u have to go for LM337 and the likes.

It is easy to get clean power from batteries. The 9V alkalines are good, but if u don't want the hassle of replacing them, then install NiMHs and a charger. Also wire a ON/OFF switch for the charger.

Gajanan Phadte

gmphadte · 21st November 2008, 08:50 AM

Correction
Not LM337 but LM317

star882 · 21st November 2008, 09:11 PM

http://www.maxim-ic.com/appnotes.cfm/an_pk/883

13th November 2008, 09:23 PM	#1
sjaltenb diyAudio Member Join Date: Nov 2008	9v Highly regulated/clean PS for guitar fx Hello everyone, this is my first post on this forum. Looks to be a great forum that I can add to my list! For almost a year now I have been working on a multi guitar FX pedalboard similar to those built by Pete Cornish for David Gilmour of Pink Floyd. The board is comprised of a wooden enclosure housing around a dozen FX units. All but 3 are powered by 9vDC, most of which only pull about 5-20ma. Two of them are AC powered tube units, requiring 24vct'd ac and 12vac both at 200ma. The third is about 50ma at 15vac with an onboard regulator. I have a custom built tranformer arriving which has about 14 secondaries. (AC120 primaries). Except for those 3 FX units that require AC input, each secondary is rated at 12v 100ma (two are 200ma) I want to build a VERY VERY clean noise free highly regulated power supply for each individual secondary and therefore each FX board gets its own independent power to reduce ground loops etc. I am new to power supply design, but understand the basics. I want to to be VERY clean but I do not want to use something as complex as the Super Regulated supply i found on this board earlier. I saw in pictures that Pete Cornish uses extremely large (at least 10,000uf) filter caps directly after the bridge rectifier so I plan on doing this if possible with my transformer specs. My questions are: with the 7809, and the 12vac power supply at 100ma (remember only about 20ma needed) How large can/should I go with the Filter cap and then what other features should I include to make it a very good power supply? I will post pictures of my board and an idea for a schematic I have so far. Thank you! Sorry for the lengthy post!!

21st November 2008, 09:11 PM	#5
star882 diyAudio Member Join Date: Mar 2007	http://www.maxim-ic.com/appnotes.cfm/an_pk/883 __________________ "Fully on MOSFET = closed switch, Fully off MOSFET = open switch, Half on MOSFET = poor imitation of Tiffany Yep." - also applies to IGBTs!

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13th November 2008, 10:39 PM	#2
sjaltenb diyAudio Member Join Date: Nov 2008	the inside is sprayed with EMF shielding paint... a lot of progress has been made since these pics but you get the general idea...

21st November 2008, 05:00 AM	#3
gmphadte diyAudio Member Join Date: Jul 2003 Location: Dona paula, Goa	If u need clean power supply, then 7809 will not do. At least u have to go for LM337 and the likes. It is easy to get clean power from batteries. The 9V alkalines are good, but if u don't want the hassle of replacing them, then install NiMHs and a charger. Also wire a ON/OFF switch for the charger. Gajanan Phadte

21st November 2008, 08:50 AM	#4
gmphadte diyAudio Member Join Date: Jul 2003 Location: Dona paula, Goa	Correction Not LM337 but LM317

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