I thought I had a great idea... but...

[digi2t]

Well, I was getting ready to do the final assembly on my Geofex Double Spyder (16 outs), when I realized that I didn't have enough stand-offs to mount the board. "Bummer!" I thought, especially since it's Saturday, and my two local electronics suppliers are closed on the weekend.

As I've done many times in the past, I decided to cruise through my local hardware store. Often times, it inspires new ideas, or I manage to find some item that I can transform for my needs. This time was no exception. Browsing through the plumbing section, I came across 3 foot lengths of 1/4" plastic speedway pipe. "Perfect!" I thought. I'll just cut it down into short pieces that I'll use as standoffs. I grab two lengths and decide to head for the register.

But wait...

As I look to my left, I see packs of rubber fawcet washers. They have the flat ones, and the thicker, one side conical ones. I decide against the speedway pipe, thinking of the time saving, and the uniformity of the washers. I drop the pipes, and grab the washers.

Back to the bench, I throw the rubber standoff washers in, bolt it all together (all 25 of them), and fire it up. Checking my output voltages, I have 10 in the 9 volt range, and 6..... at 17 volts? WTF!!!!?

I had checked everything before casing it, so I assumed something was shorting against the case. Maybe? Take it all apart, do a visual. Nope, everything is good. Put it back in the case. 6 outs at 17 volts. Specifically the 6 of the back row. Check this, check that, no dice. 9 volts out of the box, 17 in the box.

I spent what seems like about an hour, just sitting there, staring at it. My brain was like a squirrel in a blender.

Then.... a fleeting thought......

I pulled a rubber washer out of one of the packs that I had bought, and put it on the bench. I then turned on my DMM, switched it to Ohms, and stuck the two probes into the washer.

5K... damn... the bloody things are conductive. In making contact between the vero strips, and the metal base, they were screwing with the resistance in and around the voltage regulators.

Luckily, I built it on vero, so I used the washers, but I isolated the points of contact of each washer.

Retest, everything is good all around.

Funny how life is sometimes. We can conjure up the most elaborate of plans, but sometimes, it's the most benigh thing that derails us.

[Govmnt_Lacky]

OK... Im confused 

Is it a great idea or not??     

[digi2t]

OK... Im confused 

Is it a great idea or not??     

Kinda sorta maybeeeeeeee.... OK. 

The power supply is tops! No hum, no buzz. Dead quiet. Just did a switch test, between it, and a battery. I couldn't hear any difference. Me likee loooong time.

[PRR]

> the bloody things are conductive

Very interesting!!! (But annoying in this application.)

Not too un-expected (in hindsight). Rubber is not all that strong. Carbon dust is an excellent filler for rubber-- it helps the rubber stay together, it resists abrasion, it lubricates when the rubber squishes, and it's *cheap*.

IIRC(?), car tires are half carbon-dust.

Many good hardware stores have nylon spacers, sometimes even internally threaded, hidden in one of the oddball screws&springs drawers.

Also maybe nylon screws and nuts. Screw through case, nut to hold, maybe another nut for more space, PCB/Vero, nut. Yes, buying a lot of nylon nuts at 1-each prices is expensive.

If you have a sharp saw, BIC pen tubes can be sliced to spacers.

Is this the job with a lot of 120V wiring on pins? Is the box metal? I'd throw a sheet of heavy plastic (laundry detergent bottle, real-estate sign) under the board so a SLAM in the van which might collapse a standoff doesn't mean 120V is touching the case.

[Greenmachine]

Maddison Electronique is open on Saturdays (Laval), they've got a great selection of standoffs.  Plastic ones too I believe.

http://www.maddison.ca/contact_us.html

[pinkjimiphoton]

lol...

great story. funny how stuff works like that... you think, rubber, you think "insulation".

would love to see your vero for that bro... i bought the power supply and regulators from small bear to build this last year, i still haven't looked at it.

[Quackzed]

how cool would it be to cut some pieces of conductive rubber and just stick components into em!!?!
ok ok, its a bit dippy(drippy?) but still... if you could cut a bunch of strips into different resistances, or perhaps find a few different 'recipes' of carbon/rubber
for high vs low resistance... just write the resistance on the pieces.... tin your input wire, stab it into a 2k piece along with cap, other end of cap into base, collector gets 33k also 9v+...
you could probably do a rubber fuzz in under a minute!!!

[digi2t]

how cool would it be to cut some pieces of conductive rubber and just stick components into em!!?!
ok ok, its a bit dippy(drippy?) but still... if you could cut a bunch of strips into different resistances, or perhaps find a few different 'recipes' of carbon/rubber
for high vs low resistance... just write the resistance on the pieces.... tin your input wire, stab it into a 2k piece along with cap, other end of cap into base, collector gets 33k also 9v+...
you could probably do a rubber fuzz in under a minute!!!

OK... who's your dealer... and can I get some too?

@Paul - Now that you mention it, you're absolutely correct about the carbon content. I just talked to my work partner, who used to work at Goodyear before. Carbon black is a key ingredient in the mix. Probably in the washers as well.

@greenmachine - I didn't think about Maddison. Probably because I never go there. I'm usually found at Abra, or Axxesotronic.

I've posted this in the pics section, here ya go. I used individual transformers. It was a bit cheaper, and I wanted to keep everything separate, including the transformers. If I had one c0cokeyed, I didn't want to lose half the rig.

The box is a Modicon Modbus repeater. They upgraded all the PLC comms at work, so I decided to give this one a new purpose in life. Sorry Jimi, there's no vero per se. I used one big board, arranged everything on it, and then made my cuts and soldered. I didn't want 8 baby boards.

[John Lyons]

So what do you plan on running with that Dino?
Each of those transformers/voltage regs should run at least 5 pedals. 
Even at one each 16 pedals is a lot.

[Quackzed]

OK... who's your dealer... and can I get some too?

 

[digi2t]

I got fed up with the wall warts, and I wanted a power supply "to end all power supplies" kind of deal. What really sent me over the edge was my daisy chain adapters, I couldn't use them with any pedals with a lot of gain, they just weren't clean enough. Sometimes the noise would be terrible.

Besides, my rig is all rack mount, with the top shelf reserved for pedals. They all run into a dedicated 16 x 16 MIDI audio switcher, and they're on all the time. Since I can run a max of 16 pedals, I figured a 16 out PS would be perfect. Also, I really wanted each out to be isolated. No more ground loops, no more noise, and only one plug. Good bye power bars.

If the transformer can handle 5 pedals, perfect. That means it will be loafing with one, and should have a long and healthy life.

[PRR]

Very neat. Love the case.

[digi2t]

Thanks Paul.

I just need to validate something here. The transformers are 110vac primary / 12vac secondary. The secondary current rating is 60mA (0.060mA). The voltages give me a turn ratio of 0.11, which by my calculations, for 16 transformers, should give me a primary current draw of 0.1A.

I just need another brain to look at this, before I go sticking the wrong fuse in it.

@Jimi -  Here is the lay of the land as it is in my unit. I've drawn the foot print for one transformer, and the attached components. The space on either side of the transformer (top and bottom of vero) is where the ears of the transformer sit. With multiple transformers, you can overlap the ears, thus saving space. The space beyond D2 (to the right of the vero) is space I alotted between rows, I brought my L1/N lines down the next set of holes beyond D2. This could vary acorrding to the set up, but I had the space available, so I went for the max.

If it seems like I've got a lot of cuts, it's because I didn't want to take any chances on 120vac meeting up wit 12vac, or 9vdc for that matter! You'll need more cuts between your rows. Look at it carefully, and make the cuts necessary to keep everything isolated.

FAIR WARNING!!!

I DO NOT ENDORSE THIS FOR USE FOR ANYONE. THIS IS MY BUILD, AND I AM RESPONSIBLE FOR IT. MAINS VOLTAGE CAN BE LETHAL, OR AT THE VERY LEAST CAUSE PROPERTY DAMAGE IS NOT HANDLED PROPERLY. IF YOU'RE NOT COMFOTABLE WITH THIS, THEN SEEK THE ADVICE OF QUALIFIED, CERTIFIED PERSONNEL. PLEASE OBSERVE YOUR LOCAL ELECTRICAL CODES AS WELL. YOUR INSURANCE COMPANY MAY NOT APPRECIATE YOU OTHERWISE.
IF YOU HURT, MAIM, KILL YOURSELF, OR BURN YOUR HOUSE DOWN, OR ALL OF THE AFOREMENTIONED, DON'T COME CRYING TO ME!

[pinkjimiphoton]

wow, that , i mean THAT is a thing of beauty!!!

nice bro!!

mine will be different, if i ever get to it...mine is one transformer, with 8 11vdc secondarys and 1 9vAC secondary.

steve at small bear stocks them. what i'd originally envisioned doing with it has to wait til i find a proper enclosure.

i routinely run 17-25 pedals at a gig often, so i'm figuring i'll subgroup like with like, ie: pnp fuzzes, certain modulation pedals or whatever...whatever it takes to get it nice and quiet, and clean...and @2A, the AC tap will work for my whammy, too.

it's gonna be nice having all the different pedals i don't ordinarily use because of power supply noise issues...other than having to move it all, lol.
i think if i built it all into one pedalboard, it would fill the back seat of my car and weigh as much as ME, lol!

[digi2t]

Yeah, I almost pulled the trigger on the Weber transformers, but went with my gut on keeping everything separate in the end. I really didn't fancy losing a whole bank if a tranny crapped out on me.

Even with your transformer, you could use the same layout. You can isolate the rectifying section of the vero, and simply connect to secondary wires to the AC side of the bridge.

I'm on vaction until next week, but if you're in no rush, I could see if we have any of these Modicon boxes left at work, and snag one for you. You could easily fit a Weber transformer, and an 8 rectifier vero in there. If done right, you could create enough room in there for future expansion (double the outs). Or, if I do snag one, you can just send me your parts, I'll put it together for you, and then just ship the complete box to you.

Let me know.

[pinkjimiphoton]

dude, that's so kind of you.. yah, if you can find another one of them, let me know!
i believe i've got all the regulators etc already, too. i'll have to look, it was at least 6 months ago i got the stuff in...and well, ya know...so many fuzzboxes...

[digi2t]

dude, that's so kind of you.. yah, if you can find another one of them, let me know!
i believe i've got all the regulators etc already, too. i'll have to look, it was at least 6 months ago i got the stuff in...and well, ya know...so many fuzzboxes...

Let you know next week.

[PRR]

> transformers are 110vac primary / 12vac secondary. The secondary current rating is 60mA (0.060mA). The voltages give me a turn ratio of 0.11, which by my calculations, for 16 transformers, should give me a primary current draw of 0.1A

Yes, that math works out.

You should add the transformer losses. The iron loss is easily 10% (for small iron). Since the transformer winder won't be paying your electric bill, and anyway 1VA loads don't amount to much money, the transformer losses may be much higher. OTOO 30%.

BUT I have had trouble with 1/4A fuse on one small transformer. There is a large turn-on surge, some in the iron and a lot from all those caps.

The upper-limit is: how big a fire can you risk?

I can picture one of those tiny irons dead-shorted, hardly warming the lamp-cord, smoking for a minute and then quitting. It will stink, and just-might-barely set paper on fire. But the construction ought to contain the heat without major drama.

I'd start 1/2A. If that randomly blows on turn-on, even 1A.

[digi2t]

OK Paul. 1/2 amp is what I have in there right now, and it hasn't been a problem. I had figured upon the inrush of all the caps charging, but I was on the fence on whether to go 1/2, or 1/4 amp. Since I haven't tried it yet with 16 pedal sucking on it, I'll stay with the 1/2 amp, and see what happens.

Thanks again! 

[petey twofinger]

only an hour ?