am i gonna kill myself trying to do this? seriously? power supply advice sought

[Earthscum]

Here's how I have my stuff mounted for my tube project. It's not soldered at the moment, just hooked through the eyelets. I have an aluminum plate that will mount between the upverter and the tube board for shielding, and a +/-15V, 100mA brick supply that mounts in the open area (I took it out to get a better view).

Might give you some ideas.



For others that come across this, note the ground to chassis, as R.G. mentions. I had a short the first go around and didn't have my chassis ground bolted down (testing phase). I got live wire to AC through my bass. I got lucky and didn't touch anything, the hum gave away that something was not right. Now the ground goes in before I even start the rest of the wiring, and goes where I can see that it's secure, lol... I got a bit paranoid knowing I was a couple inches from possibly hurting myself pretty bad... again.

[Earthscum]

I was just looking at this again, and I'll second Paul's concern. For safety's sake, PLEASE PLEASE PLEASE, FUSE THE PRIMARY. And not will a piece of foil from your cigarette pack either  .

I can't believe that I can say it, but I've seen it done to a tube amp. They guy had been playing it since the 70's (so, about 20 years at the time). He swore up and down that all fuses kept blowing but nothing was wrong, and a certain size piece of aluminum foil wrapped around a dowel has worked fine for him. Even claimed that it blew a couple times at gigs. Tin foil hats (shielding) and rabbit ears (which are now obsolete) are where I draw the line, lol.

[R.G.]

I'll sketch something up, but the minimum you need is a UL/CSA/TUV/etc. rated strain relief or power entry socket for the AC power line, a fuse on the **line/hot** side which prevents your transformer from starting fires if it happens to be or become defective. In the case of this thing, I can't imagine that needing to be bigger than 0.5A, probably smaller. It needs to be time-delay (also called slo-blo or slow-blow).

A really good way to do this is to use a fused IEC power entry plug, like the one I used here:

This lets you use any IEC style power cord, not mess with strain relief grommets, and contains the line fuse, on the line conductor, inside a little tray in the power entry plug.

That is a Vintage Voltage Adapter for a Fender Deluxe. The power transformer is probably bigger than yours. Notice that I used both an IEC entry and an output plug for the amp, as this is intended to knock 12V off the prevailing 125Vac to get 112Vac to an older amp. The box itself is grounded to the AC safety ground, although it's hard to see in this photo. I also stuck a neon power indicator on the box so the guy would know that AC is getting to the inside of the box, in case the fuse blew. This is now living peacefully inside a 1960s Fender Deluxe, and touring.

The box is, as I remember, 2.5" tall. You'd need a slightly bigger box, but it would make sense to put your regulators and all inside the box and have your jacks on the box itself, saving the breakout box.

[Earthscum]

The box itself is grounded to the AC safety ground, although it's hard to see in this photo. I also stuck a neon power indicator on the box so the guy would know that AC is getting to the inside of the box, in case the fuse blew.

I got the switch for my box at RS. It is made to run the 2 LED's in the bezel straight from AC line, so it works similarly. If I have AC to the box, i.e. the fuse isn't blown, the switch will light up. Didn't plan on it, but I figure I'd use it to my advantage in the same way. I bought it because it was rated for what I need and it looks cool   

[pinkjimiphoton]

DO fuse the primary.

Since you are in 230V land, use a DPST _power_ switch.

Transformer rated output is (2 * 9V*2A) plus (8 * 11V*0.3A) or 63 Watts. Input power may be 20% higher, 76 Watts. 76 Watts divided-by 230V is 0.33 Amps from the wall. With cap-input supply(s) you use a Slo-Blow of twice this size: 0.6A or so. 1A may be fine. The fuse is not to protect from small overloads which may stink the transformer, it protects from dead-shorts which could burn wire and start a fire.

hi paul,
thanks for the advice...well heeded, and what i needed to know.

it's a 110v project tho, i'm not using the 220/240v taps. those will be shrinkwrapped and taped off. the only dif between the transformer i'm using and the 110 v one is the extra taps and being in stock.

so if i get this right, then probably a 1 amp slow blow fuse should be good?

should i also fuse the secondary ac tap that will be feeding the whammy pedal? since that draws up to 1.3 amps, should i go with a 1 amp slow blow there as well?

i'm also gonna add one more diode to each section, with cathode toward pin one of each 7809 and anode toward pin 3 to protect against reversed polarity...or is that overkill?
seems it would cause a bit of a voltage drop after the regulator..

i'm a newb, so i have ENDLESS questions!!

thanks!

[pinkjimiphoton]

Might be an idea to build and test just one reg first, to confirm you got all the parts in the right way around. Otherwise you could blow 8 regs in one foul swoop. (Or put all the parts in but only hook up one reg to 11V AC for a test).

Oh, sure - do it the smart, effective way!

this IS me, we're talking about here. 

sage advice!! lol

[Earthscum]

The secondary AC tap shouldn't need to be fused. It's more of an issue of making the plug different somehow so you don't accidentally plug a different pedal into it that can't handle the juice.

[pinkjimiphoton]

... and one separate 2.1mm jack to feed the 9vac output to power my digitech whammy.

You do realize that having 9Vac available on the same size connectors puts 100% of your 9Vdc pedals at risk of being fried if you accidentally plug in 9Vac to one of the DC pedals in a moment of confusion, don't you?

hi rg, here's the thing...all the DC pedals will be connecting with standard pedalboard jumpers, 2.1mm on the end that plugs in the effects, and 1/8th inch on the side that plugs in the breakout box.

the 9vac will be the only output jack on the breakout box that will accept the 2.1mm plug on both pedal and power supply end.

see dat? i'se smrat!

well...smart enough to ask ALOT of questions!!!!!!

I can't recommend strongly enough to make the 9Vac hard to mix up with the 9Vdc. The pedals you save could be your own.

done!!

is this gonna be dangerous? it's gonna be hard to keep the wires from the transformer separated when soldering to the veroboard, but
i've built tube amps before and think i'm up to it.
...
does it NEED to be boxed up? or is it better to let air to it , so it can dissipate heat?

i'm planning on mounting the transformer to the underside of the wood part of the pedal board, and having the wires from the secondarys go to a breakout box that'll be mounted topside.

We really want you with us to keep making music. It is critical for your safety that 100% of the AC power part of this and the transformer be boxed up. Ideally, this would be a metal box, grounded to safety ground. It's marginally acceptable for the transformer secondaries to come outside the box, but it's a fried transformer waiting to happen if something cuts into and shorts a couple of wires.

AC power on a pedalboard is like carrying your pet rattlesnake around. It's interesting and fun, but if it ever sneaks out of some opening, it's going to bite you or someone who's standing near by. There should be no possible way the AC power rattlesnake can get out of the grounded metal box.

ok....makes perfect sense.

i may have to use two boxes then...there's just no way i can fit the transformer in a box, tho i can definitely put the primary wires into one. there's just not enough room under the board to even fit the transformer...the transformer will have to be mounted topside of the board, and each set of wires will have to feed thru to the underside.

otherwise, i need to build a separate chassis for the whole mess..which defeats the purpose of having just three cords to plug in. my back is wasted (broke it long ago) so the less bending/patching the better!!!

so now i'm figuring a metal box for the primary and 9vac tap, and mounting the other 16 dc outs in a PLASTIC box for the secondarys to make sure there's no ground loops across the mounting plane....for some reason, my smrat bwain forgot that the whole purpose of this was to minimize ground loops and noise...so having a common ground plane for all the dc effects has gotta be a no-no, correct?

thanks rg!

[pinkjimiphoton]

DO fuse the primary.

Since you are in 230V land, use a DPST _power_ switch.

Transformer rated output is (2 * 9V*2A) plus (8 * 11V*0.3A) or 63 Watts. Input power may be 20% higher, 76 Watts. 76 Watts divided-by 230V is 0.33 Amps from the wall. With cap-input supply(s) you use a Slo-Blow of twice this size: 0.6A or so. 1A may be fine. The fuse is not to protect from small overloads which may stink the transformer, it protects from dead-shorts which could burn wire and start a fire.

I was just looking at this again, and I'll second Paul's concern. For safety's sake, PLEASE PLEASE PLEASE, FUSE THE PRIMARY. And not will a piece of foil from your cigarette pack either  .

no worries, keppy...

first, it's gonna run at 110 (american) not 220/240

second, i'm gonna put in the smallest fuse i can get away with.

i wanna die real old with a redhead on each arm, a doob hangin' outta my craggy ancient beak, late for my own funeral, not slumped over my workbench!

[pinkjimiphoton]

Here's how I have my stuff mounted for my tube project. It's not soldered at the moment, just hooked through the eyelets. I have an aluminum plate that will mount between the upverter and the tube board for shielding, and a +/-15V, 100mA brick supply that mounts in the open area (I took it out to get a better view).

Might give you some ideas.



For others that come across this, note the ground to chassis, as R.G. mentions. I had a short the first go around and didn't have my chassis ground bolted down (testing phase). I got live wire to AC through my bass. I got lucky and didn't touch anything, the hum gave away that something was not right. Now the ground goes in before I even start the rest of the wiring, and goes where I can see that it's secure, lol... I got a bit paranoid knowing I was a couple inches from possibly hurting myself pretty bad... again.

'


looks great dave...nice and clean.

i would LOVE to be able to put the whole thing in a box...but the dang transformer is way bigger than i thought...just a smidge taller than a standard boss pedal and about as wide.

since the whole mess is mounting in a stratocaster case i gutted, which just barely closes, it's gonna be a fight to make it all work.

i may try putting the board etc into a p-bass case instead, like i did in days of yore..if it will fit. that may give me enough crucial room to be able to mount it all in a box if i do that.. so i'll investigate it.

[pinkjimiphoton]

I'll sketch something up, but the minimum you need is a UL/CSA/TUV/etc. rated strain relief or power entry socket for the AC power line, a fuse on the **line/hot** side which prevents your transformer from starting fires if it happens to be or become defective. In the case of this thing, I can't imagine that needing to be bigger than 0.5A, probably smaller. It needs to be time-delay (also called slo-blo or slow-blow).

A really good way to do this is to use a fused IEC power entry plug, like the one I used here:

This lets you use any IEC style power cord, not mess with strain relief grommets, and contains the line fuse, on the line conductor, inside a little tray in the power entry plug.

That is a Vintage Voltage Adapter for a Fender Deluxe. The power transformer is probably bigger than yours. Notice that I used both an IEC entry and an output plug for the amp, as this is intended to knock 12V off the prevailing 125Vac to get 112Vac to an older amp. The box itself is grounded to the AC safety ground, although it's hard to see in this photo. I also stuck a neon power indicator on the box so the guy would know that AC is getting to the inside of the box, in case the fuse blew. This is now living peacefully inside a 1960s Fender Deluxe, and touring.

The box is, as I remember, 2.5" tall. You'd need a slightly bigger box, but it would make sense to put your regulators and all inside the box and have your jacks on the box itself, saving the breakout box.

looks great.

i'm planning on using the power jack from a scavenged computer psu...it has the hot lead wrapped around a torroid choke just after the input, figured from there i'd connect to the fuse holder. call me old-fashioned, but i like the classic old school fuse holders like fender used...to me, it's just easier than the modern integral ones if ya need to get at it.

so you figure .5a fuse is gonna be cool?

my princeton is supposed to run a 3 amp fuse, i run it on 1...never have had a problem yet (knock on wood)..

[pinkjimiphoton]

The secondary AC tap shouldn't need to be fused. It's more of an issue of making the plug different somehow so you don't accidentally plug a different pedal into it that can't handle the juice.

ok, cool...is there any kind of filtering i should use on it?

or would that convert it to ac?

sorry for all the questions, but i wanna get this RIGHT .

and i don't wanna see my whammy become a casualty!

[pinkjimiphoton]

hey one more question...

if i reverse the diode bridge on one of the "channels" and reverse bias the cap, will that give me a -9v power supply? like...to run my fuzzface with?

or am i better off to just add a tiny daughter board with a max1044 or something on it to run the fuzzface?

[PRR]

Earthscum> Here's how I have my stuff mounted for my tube project

I've seen worse, I've done worse. And seen it go wrong.

Being picky:

I (and most inspectors) would like to see a Green wire (whatever your code favors) for the Dedicated Case Ground/Earth.

And the grounding screw really should be Dedicated. Not doing anything else. I blink at big-amplifier power-transformer bolts; they are not going anywhere. But the IEC entrance unit gets a lot of yanking and kicking. I have seen them loosen up.

I would prefer a larger gauge and insulation through the primary circuit. Inside the (metal or flame-resistant) case the standards are lower, but still I want the wire to hold-on much longer than the tinfoil on the dowel (or fuse).

What is the black box inline to the switch? Is it loose? If so, eventually (maybe not for decades depending on abuse) it will break the wires. A live wire-end loose in the chassis is potential trouble.

It is wise to pry-open some recent commercial gear for study, or even to hijack the entire primary-parts system.

My best joke-on-myself: everything wired tight and neat and tested open on the bench. Close it up, put it in the rack, got a bad shock. Open, AOK. Closed, ZAP. Finally traced it to a cover-screw poking a wire.

[PRR]

> if i reverse the diode bridge on one of the "channels" and reverse bias the cap, will that give me a -9v power supply? like...to run my fuzzface with?

You have missed the whole point of Separate Windings. Forget convention. Look at your 11 power supplies. Which DC wire is "ground"? Neither! Just like a battery. Ground happens when you connect it to the audio pedal. If you have a positive-ground pedal, the + wire goes to audio ground and the - wire goes to the collectors supply.

[pinkjimiphoton]

thanks paul, i realized i was in outer space after i thought about that. 



i'm good to go now i think.

appreciate the help everyone!

[Earthscum]

Paul, picky or not, standardization, safety, and longevity are always good advice. Thanks much.

Good luck with this project, Jimmy. Hopefully I'll be hitting up the same thing soon. I'm getting sick of battery fails in the middle of sets, lol. Little Angel turns to a little banshee, gremlin, or otherwise just short of a poltergeist on low battery. It is fun to watch a crowd imitate "The Scream", tho.

[fair.child]

Hey jim,

nice project to build,

but I have a question, why did you use 7809, instead you can also use LM317 ? Can you give several explanation about building your power supply, because I also will use 2A transformer to build one like yours but probably with 1k-5k trimmer to change the voltages (9V-12-18V DC ranges), is it possible if I have 2A transformer and use LM317 as a regulator ? or Should I built my Power Supply with 7809 to handle higher current (up to 1.5A-2A) ?

Thank you

[Earthscum]

First, each secondary only supplies 11V, and the regulator eats up over a volt of that. Realistically, you could only get about 9.5V or so, unless you build a voltage doubler (easier with AC already present).

Second, the 9V regulator uses 2 less resistors. If you are just using 9V, then save yourself a couple pennies, board space  and holes.