9V 2A Guitar FX Pedal Power supply

moody07747 · Jul 5, 2006

I saw a thread at another board for guitars where someone had a pedal board adapter made up for powering all his guitar pedals.

a few photos of the setup (link removed due to deleted old pics)

Yea they are not the best but I asked if he could get better ones.

I could care less about the whole clear case and blue LEDs on this one.
I just need a good, quiet power supply that will put out 9V and up to 2A to power up to 8 guitar FX pedals.

Now I know how to make a power supply by following sheets but I need some advice on how to keep it "Quiet" in the audio part. I can't be having that 60Hz buzz in my audio lines...I already have that problem.

So bring on the wiring sheets and tips/tricks

moody07747 · Jul 5, 2006

btw, i was looking at this circuit
https://www.aaroncake.net/circuits/supply6.htm

but that transformer may cause buzz...is there any way to do a transformerless supply?
or would a metal box keep the buzz out of the lines?

HiTech · Jul 5, 2006

If you play an axe and you also dabble with electronics then this site is a MUST! You'll spend days clicking through the myriad of links and good info.

http://www.musicianstechcentral.com/schmatic.html#misc

The Xformer shouldn't introduce 60hz hum if you use a metal project box as well as keeping wires short and also loop a couple of turns of them through a ferrite donut or similar.
Below are some links to what you are looking for:

http://www.generalguitargadgets.com/pdf/ggg_reg_power_supply.pdf

a very clean pwr. supply:
**broken link removed**

here is the complete page of details on the above "clean" power supply:
http://www.generalguitargadgets.com/index.php?option=content&task=view&id=77&Itemid=106

Of course there are many websites with similar pwr. supply projects but this one seems fine and dandy. BTW, what guitar do you have? I have an original 1963 Stratocaster w/ original hardware, pickups, etc. It's worth a ton of money these days (thousands $$$) and to think I bought years ago for $125 from a guy that hated it and wanted a lower model Gibson instead!!

moody07747 · Jul 5, 2006

HiTech said:
If you play an axe and you also dabble with electronics then this site is a MUST! You'll spend days clicking through the myriad of links and good info.

http://www.musicianstechcentral.com/schmatic.html#misc

The Xformer shouldn't introduce 60hz hum if you use a metal project box as well as keeping wires short and also loop a couple of turns of them through a ferrite donut or similar.
Below are some links to what you are looking for:

http://www.generalguitargadgets.com/pdf/ggg_reg_power_supply.pdf

a very clean pwr. supply:
**broken link removed**

here is the complete page of details on the above "clean" power supply:
http://www.generalguitargadgets.com/index.php?option=content&task=view&id=77&Itemid=106

Of course there are many websites with similar pwr. supply projects but this one seems fine and dandy. BTW, what guitar do you have? I have an original 1963 Stratocaster w/ original hardware, pickups, etc. It's worth a ton of money these days (thousands $$$) and to think I bought years ago for $125 from a guy that hated it and wanted a lower model Gibson instead!!

Thanks for all the links, ill have a look at them all.

killer deal on that guitar. I am just starting on guitar, got a PRS SE (older version) last month but I'm learning it fast even without lessons.

if you look in my sig like ill have my web page at myspace.com I will be putting up a song in a day or two, I'm working out some of the details in editing now and have to add drums and keys.

Dr.EM · Jul 5, 2006

That clean supply posted with the LM317 is good. Something that seems silly to me is the use of a 25v transformer though. That gives around 34v at the input to the regulator! This high input voltage will waste serious power to give a 9v output. Use a 12v transformer instead if you use that design, it will give plenty of voltage, even 9v may do, it would with a lower dropout reg. You may need to up the value of the 1000uf smoothing cap though.

moody07747 · Jul 5, 2006

Dr.EM said:
That clean supply posted with the LM317 is good. Something that seems silly to me is the use of a 25v transformer though. That gives around 34v at the input to the regulator! This high input voltage will waste serious power to give a 9v output. Use a 12v transformer instead if you use that design, it will give plenty of voltage, even 9v may do, it would with a lower dropout reg. You may need to up the value of the 1000uf smoothing cap though.

Thanks for the tip

Also, im going to take a guess and say that they ment a 68K resistor, not a 6k8

**broken link removed**

moody07747 · Jul 5, 2006

ok i got 90% of the parts from the list link above but i still have to find the following

2 - 0.1uF (min. 35V)

1 - LM317 Transistor

I tried to get the parts all from allelectronics.com but the 6 - 1N4002 diodes had to come from mouser.com

as for that 1,000uF cap change, I ordered a 12V transformer and a 2200uF 35V to counter it.

Dr.EM · Jul 6, 2006

The diodes arn't too critical, anything 1N4002, 03, 04, 05 etc is fine. Alternatively, for those 4 a bridge rectifier could be used as that is what the diode arrangement is doing (1A, 100v min).

For the 0.1uF, use ceramic caps, (100n as they'll be listed). They are there to stop the LM317 oscillating and ceramic have the best high frequency bypass caracteristics. Install them as close to the 317 as you can. 25v rating is fine on them seeing as you are using the 12v transformer.

The LM317 is very common, was it out of stock? It is an intergrated circuit, variable voltage regulator, not a transistor though in case you were searching the wrong terms.

moody07747 · Jul 6, 2006

got everything from allelectronics.com.

i did however find one of my old regulator ICs from that power supply that went from 1-30 VDC back a few months ago.

its the "LM317T Adjustable Voltage Regulator"

it looks like it will work so ill give it a try.

I got the following parts all from AE.com

(old photobucket link removed)

moody07747 · Jul 10, 2006

OK I just got all the parts in today for the power supply...some from all over the place.

I layed the parts in a blank board that's about 2" x 1.5" and ran into some problems near the end which I should have caught days ago when I ordered.

The list of parts seen here
**broken link removed**

Says to get a "6k8" 1/4W resistor

Whats that?....While on the layout it calls for a "6k81" resistor

Another one that I found was in the parts list
A "270"ohm resistor is called for there but on the layout for the diode bridge seen here

**broken link removed**

A 274ohm resistor is in place, what should I use there?

When I ordered I looked at the parts list and assumed it was meant to be a 68k resistor and got that but looking at the layout and schematic sheets I think its supposed to be a 6.81k 1/4W (in place at r2b )

**broken link removed**

Last time I emailed the guy it took 4 days of waiting for a response and I really don't want to have to wait that long just to make another order which will delay me even more.

If you have any thoughts on what these parts should be post them.

Thanks

Nigel Goodwin · Jul 10, 2006

moody07747 said:
Another one that I found was in the parts list
A "470uF" cap at 35v min. is called for there but on the layout for the diode bridge seen here

Use a 470 or a 1000, it makes very little difference (try reading the tolerance on the side of electrolytics!).

**broken link removed**

A 274ohm resistor is in place, what should I use there?

When I ordered I looked at the parts list and assumed it was meant to be a 68k resistor and got that but looking at the layout and schematic sheets I think its supposed to be a 6.81k 1/4W (in place at r2b )

6K8 is the standard way of listing a 6.8K resistor, the 6k81 is probably a mistake, likewise 274, it should be 270 ohms.

moody07747 · Jul 10, 2006

thanks...time to order more parts and play the waiting game.

Hero999 · Jul 10, 2006

Nigel Goodwin said:
likewise 274, it should be 270 ohms.

You never know it could be 270k ohms, but I agree with you when looking at the circuit.

moody07747 · Jul 10, 2006

OOPS!!!

i made a big edit on that original post...

i said something about a capacitor then went talking about the resistor...that's what happens when you stay up all night working on things that have to get done lol

anyways here's how it should be worded:

Another one that I found was in the parts list
A "270"ohm resistor is called for there but on the layout for the diode bridge seen here

**broken link removed**

A 274ohm resistor is in place, what should I use there, the 270 or 274ohm resistor?

its probably one of those that wont make much of a difference but better safe than blowing up parts lol

Nigel Goodwin · Jul 10, 2006

moody07747 said:
A 274ohm resistor is in place, what should I use there, the 270 or 274ohm resistor?

What was wrong with my previous reply to this question?.

audioguru · Jul 10, 2006

The project uses a 274 ohm 1% resistor in parallel with a 2k resistor, and a 6.81k 1% resistor in parallel with another 2k resistor.
I would just use a 120 ohm 5% resistor for the resistor from the output to the ADJ terminal, and a 750 ohm 5% resistor for the resistor from the ADJ terminal to ground. Then its output voltage will be close to 9V.

moody07747 · Jul 10, 2006

audioguru said:
The project uses a 274 ohm 1% resistor in parallel with a 2k resistor, and a 6.81k 1% resistor in parallel with another 2k resistor.
I would just use a 120 ohm 5% resistor for the resistor from the output to the ADJ terminal, and a 750 ohm 5% resistor for the resistor from the ADJ terminal to ground. Then its output voltage will be close to 9V.

im not following ya on that...

you mean take out the 2k, 270, 6.8k, and 2k resistors all together and just use the 120 and 750?

if im going to under stand anything for this im going to need a wiring sheet made up with the different components in place...

philba · Jul 10, 2006

dave, take a look at figure 7 in the lm317 datasheet. https://www.st.com/stonline/books/pdf/docs/2154.pdf the guy that designed that power supply used 4 resistors instead of 2. In the datasheet you will see one resistor between output and Adjust (R1) and one between adjust and ground (R2). the formula for the output voltage is Vout = 1.25(1+ R2/R1) +Iadj*R2. For small R2s, you can ignore the Iadj*R2. What he was trying to do is get specific values of R1 and R2 so he could get exactly 9V. I would suggest you get 1% metal film resistors. R1 = 120, R2 = 732 (those are stocked values of xicon 1% metal film at mouser). This will give you very close to 9V (at least 8.95 but with the Iadj adder, it's almost exactly 9V). edit: note that 750 will get you 9.14V and 720 will get you 8.8V)

so, remove all 4 resistors from the board. replace the 274 ohm one with 120. Replace the 6K81 one with 732.

Now, I don't understand why the guy didn't just use a 7809. no resistors needed at all, Unfortunately, the pin out is different from the LM317 so the board won't work.

audioguru · Jul 10, 2006

philba said:
Now, I don't understand why the guy didn't just use a 7809. no resistors needed at all.

An LM317 with the 10uF capacitor at its ADJ pin to ground has typically less than half the ripple of a 7809.

moody07747 · Jul 11, 2006

philba said:
dave, take a look at figure 7 in the lm317 datasheet. https://www.st.com/stonline/books/pdf/docs/2154.pdf the guy that designed that power supply used 4 resistors instead of 2. In the datasheet you will see one resistor between output and Adjust (R1) and one between adjust and ground (R2). the formula for the output voltage is Vout = 1.25(1+ R2/R1) +Iadj*R2. For small R2s, you can ignore the Iadj*R2. What he was trying to do is get specific values of R1 and R2 so he could get exactly 9V. I would suggest you get 1% metal film resistors. R1 = 120, R2 = 732 (those are stocked values of xicon 1% metal film at mouser). This will give you very close to 9V (at least 8.95 but with the Iadj adder, it's almost exactly 9V). edit: note that 750 will get you 9.14V and 720 will get you 8.8V)

so, remove all 4 resistors from the board. replace the 274 ohm one with 120. Replace the 6K81 one with 732.

Now, I don't understand why the guy didn't just use a 7809. no resistors needed at all, Unfortunately, the pin out is different from the LM317 so the board won't work.

Thanks

ok so heres the new layout (older photo removed to reduce confusion)

ill order later in the day...have to get some lists of items out for the mods to the DS1

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

9V 2A Guitar FX Pedal Power supply

Member

Member

Well-Known Member

Member

New Member

Member

Member

New Member

Member

Member

Super Moderator

Member

Banned

Member

Super Moderator

Well-Known Member

Member

New Member

Well-Known Member

Member

Similar threads

New Articles From Microcontroller Tips