Picture of Build A Power Supply For Your Guitar Pedals
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If you're like me, you know how annoying it is to use up 9V batteries on your guitar effect pedals.  Its wasteful, and brand name 9V's are almost $9 for a two-pack.  If you forget to turn off your pedals you've thrown away big bucks.  Its an extreme waste of money when you can build your own power supply for only about $25.The power supply I designed and built delivers steady, regulated 12 volts, 9 volts and 5 volts all at the same time.  Each voltage has two outlets, but they can be "daisy chained" with a custom cable to connect many more pedals.  The styling is an homage to the old days of vacuum tubes, when components generated so much heat they needed to be on the outside of the casing instead of inside.  I used some gigantic capacitors that I thought would look cool, other than that they are major overkill. In this Instructable I am going to assume that you know some basic electronic skills and know what I am talking about when I say capacitor, resistor, LED, transformer, AC and DC, etc.  There are lots of introductory electronics Instructables and soldering Instructables you can check out if you'd like to gain a better understanding of basic electronic principles and components.IMPORTANT NOTE:  Depending on what pedals you intend to use this for, you should take care to wire the DC connectors as pin-positive/ring-negative or pin-negative/ring-positive.  The latter is the industry standard way of doing it, although it poses issues when building a pedal that has a metallic housing.  I prefer pin-positive/ring-negative because of that issue, and I wired this supply in this way.  Please take care as to which way you wire the power supply to prevent damage to your pedals.
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Thanks. Great Instructable. I took the same schematic and same idea, without the project box, and mounted it to the bottom of my pedal board I made! Check it out...

All six DC cables are 9v, and I put two through each hole in the board, for maximum movability.
Nice job, looks great

Hi Matt, I am a little confused on the parts. What are those two large cylinders on top of the whole power supply box. (Blue and Red on computer graphic)

Actually only blue on the computer graphic. still same question

Hi there, sorry for the delayed response, the Instructables email system seems to have broken until just today.

Those are large capacitors sticking out of the case. They are like that only for cosmetic reasons, they are much larger than the circuit requires. Feel free to use a lower value like 1000uF, they will be much smaller.
janeliza1 month ago
hi sir mat, i made power supply based on your schematic. i used a 18 0 18 @1amper transformer, but when i tested it, the output from both 3 regulators was uniformed @ 19 - 20vac. where did i go wrong.? how should i fix it sir.? tnx.
mattthegamer463 (author)  janeliza23 hours ago
You should have no AC voltage at the output of the regulators, only DC voltage. Check the pinout of your regulators to make sure they are wired correctly, also make sure your bridge rectifier/rectifier diodes are correct because you should not have that high an AC voltage if you have the rectifier and capacitors in place.

an easy way to get the power for pedals is to buy a cb regulated power supply then turn the regulator voltage down to 9 volts..might be a variable pot or a resistor change..simple getting a bit of a chuckle at how many guys are tring to complicate the issue....its a very simple problem to get around

Si HengT26 days ago

Hey Matt, I've followed the schematics, and wired everything up accordingly. Thanks a lot for the comprehensive instructions !

I'm facing a small problem though: when I check the voltage from each port, they all produce -9V DC. However, once I use a port to power my pedal, something seems to eat all the current up. My pedals are regular, 9V, and draw 14-19mA. What do you think could cause this?

Interestingly, when I try plugging in a cheaper pedal, it works just fine.

sir i have a transformer 220v to 12v outputs my problem is the transformer is have 3 pins 12v 0v 12v what should i use the 12v and 0v?

There is a way to use a center-tapped transformer without getting too high a voltage if you just ignore the center tap. This is done with a full wave rectifier as shown here:

Just replace the bridge rectifier in my circuit with two diodes to make a full wave rectifier as shown.

hi sir in your diagram where did you put the the two 1000uf volts capacitor and 3 10 uf 63v because in the diagram only 100uf numbers no voltage included sorry sir im a newbie -_-

because i count all the capacitors in the diagram there are 6 and the one i saw in your pictures is only 5 can you plase create a diagram that shown all the name of capacitors thank you sir for all the help

The value and quantity of the capacitors really isn't that important, what is important is where they are located and that the voltage rating for them is higher than the maximum voltage they will be subjected to. Subjecting a capacitor to a voltage higher than its rating can and will cause it to burst or explode. Just google this to see why you don't want this to happen.

Capacitors after the rectifying diodes (before the regulators) and after the regulators (a requirement stipulated in the 78xx regulator datasheet) is all you need. If you have major noise problems being caused by the power supply after it's built, I would suggest to add some more capacitors in parallel with the existing ones to help smooth out the voltage.

The 10000uF capacitors are oversized. They are functional but their huge value is partly cosmetic. Feel free to substitute a single 1000uF if you'd like, there shouldn't be any issue.

More info if you want to learn about it

sir i have a transformer 220v to 12v outputs my problem is the transformer is have 3 pins 12v 0v 12v what should i use the 12v and 0v?

mau12.162 months ago

Dude. I want to have 9v 8 outputs. What should I do? I already get it in replacing the other 12v and 5v regulators with 9v one. How to add another 9v in the circuit? Thanks

mattthegamer463 (author)  mau12.162 months ago
Just add some more regulators and capacitors. If you add one more (4 total) you can put two pedals on each and have your 8 outputs.
JohnF75 months ago

ahhmm, i dont get it. im sorry, you have used 18v transformer right? so, i will remove the transformer there in your tutorial and replace a transformer that can work at 220v ac? im sorry man, i am confused.. by the way im from Philippines. we have 220v ac here

mattthegamer463 (author)  JohnF75 months ago
Sorry I misunderstood. I thought you were asking how you could do this without a transformer at all. The transformer outputs 18V but takes in 110V AC. Plugging a 110V transformer into 220V will cause the output to be 2x higher, but you will be able to buy a 220V to 18V transformer there in the Philippines. The input and output are referred to as "Primary" and "Secondary" coils, which will be rated for 220V and 18V respectively.

Hi.. So can I replace your transformer with 220v AC with 18v AC secondary rating?

mattthegamer463 (author)  mau12.162 months ago

Yep, that's the way.

JohnF75 months ago

man, thanks for this tutorial. but i live in a country which i get a 220v ac., what can i do if dnt wanna use transformer? thank you. im a newbie in electrnics.

mattthegamer463 (author)  JohnF75 months ago
You have to use a transformer. There isn't any practical way to make 9V DC from 220V AC.

Huh? Of course you can do it with a Zener diodes. E.g., please read this: The other question is that it is not always that safe and if you have crappy jumping power, then all your pedalboard might puff in smokes, once you use Zeners at the limit. Transformers are just nicer and safer.

mattthegamer463 (author)  bo.maryniuk2 months ago

I would never suggest someone not use a transformer for this kind of thing, especially for 220V AC. Not just for safety reasons, but for practical reasons too. If you do the math on a zener regulator circuit, the voltage drop resistor would need to dispose of more than 10W of extra power to get 50mA on the output, enough for only one or two pedals. Also, he says he is new to electronics, which frankly means he really shouldn't be messing around with 220V AC without the knowledge of how to be safe. Transformer or no, 220V AC is dangerous.

evan.stoddard2 months ago
So with that transformer you can only use 300ma worth of pedals correct?
mattthegamer463 (author)  evan.stoddard2 months ago
Pretty much. Won't be hazardous to go over that a little bit though.
evan.stoddard2 months ago
Or do you get more since you're dropping to 9v?
Davidv37 months ago

is it a problem if you live in a country where you get 230 volt ac out of the power outlet?

mattthegamer463 (author)  Davidv37 months ago
No, you just need a transformer which has a primary rated for 230V AC and a secondary rated for 9V AC. Some transformers can be wired specifically for 115V or 230V, but probably most cannot.

what about SMPS?

mattthegamer463 (author)  Okoraokora13 months ago

An SMPS would work but the concern is that the SMPS high frequencies will cause noise and high frequency sounds.

Wouldn't a 230 – 12 VAC work too? And would the LM7809's be able to operate at all if the secondary was 9 volts? – The datasheet specifies a minimum input voltage of 11.5 volts.

It would, just that the more excess voltage you have at the unregulated DC stage, the more heat the regulator is going to generate and the less current you will have available at the output. Because the transformer current rating is selected to be higher than the current that is actually going to be used, it will be higher than 9V. The rectified and smoothed output voltage of a 9V secondary, with no load, t is probably 14-15V. Using a higher transformer rating would just produce more voltage the regulator will have to waste.

The dropout voltage in the datasheet is 2V @ 1A, but 1A is the maximum current for the part. It would probably take 8 typical pedals on one output to use that much current. The dropout voltage is lower at smaller current levels. A part like the TI LM2940CT-9.0 is an improved linear regulator design that only has a dropout of 0.5V @ 1A. It is pin compatible so it can replace the generic 7809 directly.

Thanks for the informative answer; exactly what I needed to know. :)

rocking0186 months ago

is this an isolated power supply or is that a whole different game?

mattthegamer463 (author)  rocking0186 months ago
One of these per output could be used to make a isolated supply. Cost could probably be about $20 + extra $6 per output.
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