pedal power supply question about RG's article

[mozz]

Not a joke, read it somewhere they banned transformer power supplies. Not efficient up to their standards. Now i am seeing 2008, so 10 years ago?

[nosaj]

Not a joke, read it somewhere they banned transformer power supplies. Not efficient up to their standards. Now i am seeing 2008, so 10 years ago?

Just conceal them in a shipment of medical marijuana and everything will be just fine.

nosaj

[olddawg]

For most people a One Spot works just fine. Just have a spare in your kit if you are paranoid. I’ve been using the same one several times a week for 6+ years with no issues. Most pedals have a very low current draw. I run a separate wall wort supply for my finicky EH C9 pedal. Used to have my wireless receiver on my board on a separate supply too but moved it to the top of my amp a while back.

[mikepukmel]

Not a joke, read it somewhere they banned transformer power supplies. Not efficient up to their standards. Now i am seeing 2008, so 10 years ago?

Oh man, I first read about this ages ago, and dug and dug to find info. I could not find an explicit ban, but was able to find efficiency standards doc https://www.energy.ca.gov/papers/2005-03-03_WILSON.PDF That spells out load/no load efficiency. I don't have the engineering chops to understand the numbers, but they did specify efficiency numbers, and if those numbers are just over what linear PS can deliver, then, it would be a de facto vs de jure ban. Nanny, nanny, oh nanny please save us from the evil linear power supply!

[mikepukmel]

The way I would approach it would be simpler.

1) What is the mA requirement of the highest current pedals on the market.
2) Multiply that figure by the number of outputs you plan to use.
3) Find a 12V transformer capable of 20% more current. (regulation will eat some current)
4) Regulate it to 8.6V/9V (8.6V seems to be what most 9V batteries actually put out)

Easy peazy lemon squeezey.

Cool, thanks Chuck. Part way there, anyway. Selecting the "right" transformer is a little bit of a pain for me. Thanks for the approach sketch.

[mikepukmel]

You don't need a 400mA transformer. 400 mAH means the battery can (optimistically) supply 400mA for 1 hour before it's toast or 40mA for 10 hours or 4 mA for 100 hours etc. If you are using separate transformers each output only has to supply the current required by your highest current pedal.

That's the tough part for me, Dave. RG's original page had something like 60ma transformer. I can't find those exact ones anylonger. Well, not exactly correct. The big places, Mouser, Digikey, they're obsolete and not available. Some smaller places have 'new old stock" but they want like 13 or 15 bucks for one. Seems way overpriced given what it is.

Also, not exactly sure why we would need separate transformers, couldn't we use one, and use that to power several regulator boards?

[eschertron]

Isolated transformers means isolated (floating) grounds. If that's important.

[mikepukmel]

True, who would bother building a complex SMPS when you can buy one ready made for $20 or so. And when that a power supply costs $20 more or less, buy a spare! Those who build their own PSU's would be wise to stick to the cheap & reliable, low parts count, ol' fashioned standard supply.



I hope that's a joke, but - California - yikes!

Yeah, and given that a usable, working SMPS is so far over my engineering capabilities ... its a no-op for me: buy whatever, or build a linear.

[mikepukmel]

I built a Jameco Dual Output Power Supply Kit. If you look on YouTube, you will see videos of the kit being built. Just get yourself a project box, drill some holes to mount you outputs and you're done. I am only using one side of the kit and it supplies ample power to my pedal board (7 pedals).

Thanks Tom!

[mikepukmel]

How long does the pedal work until the repair? 5 years, at best 10 years. And then it must be repaired. SPMS will work no less. MTBF for the SPMS usually is not less than 20,000 hours (2 years of continuous work without shutdown). No pedal will work so long.

For any pedal (as for any audio equipment) MTBF isn’t controlled parameter at all. And reliability is determined by luck (although the quality of development, components and manufacturing also affects).

In addition, all modern pedals (like other audio equipment) use SMPS.

Not sure I agree with you completely, Doc. My brother is a real guitarist (opposed to me who just tinker), he's got a very large collection of boxes, and several just don't work with any of the SMPS he has. They made odd, and awful noises, unless plugged in to a 9v battery. I would like to try those sensitive pedals with a clean linear supply and see how they perform.

[mikepukmel]

I built a Jameco Dual Output Power Supply Kit. If you look on YouTube, you will see videos of the kit being built. Just get yourself a project box, drill some holes to mount you outputs and you're done. I am only using one side of the kit and it supplies ample power to my pedal board (7 pedals).

Hi Tom, did you use the stock heat sinks that came with the Jameco kit? They look a little on the small'ish side. I build a power supply for another project, that had small sinks, and ended up having to get a lot bigger heat sinks, and drilling the board a bit to get them installed. Nice looking kit, though.

[nevetslab]

True, who would bother building a complex SMPS when you can buy one ready made for $20 or so. And when that a power supply costs $20 more or less, buy a spare! Those who build their own PSU's would be wise to stick to the cheap & reliable, low parts count, ol' fashioned standard supply.



I hope that's a joke, but - California - yikes!

I had never heard about this https://www.energy.ca.gov/papers/2005-03-03_WILSON.PDF standard. Seems to only apply to DC output supplies....Wall Wart style and the like. I would ignore it for building a dedicated Pedal Board supply, as those building them for themselves aren't dealing with Applicable Industry Standards that regulate what you can put on the market. On commercial pedal boards, that built-in supply no doubt takes the form of a product supplying operating voltage(s) for the accessories, much like Rack Mount products that run API 500 series console modules, and all that have adopted to that standard, of which there are a lot. You'd still have to meet the safety standards required to sell them in the US and abroad.

I too would (and have) built in the conventional format of selecting a suitable power transformer capable of supplying sufficient current with adequate headroom and thermal capacity, and not go in the direction of SMPS. Keep it simple, reliable, built to last.

[olddawg]

Not sure I agree with you completely, Doc. My brother is a real guitarist (opposed to me who just tinker), he's got a very large collection of boxes, and several just don't work with any of the SMPS he has. They made odd, and awful noises, unless plugged in to a 9v battery. I would like to try those sensitive pedals with a clean linear supply and see how they perform.

I’ve run into that problem a couple of times. Like I said earlier.. that EH C9 is a REALLY finicky piece of work (Like sometimes it’s a crap shoot if it works at all if I forget to check it at set up for a gig.) It comes with its own supply. I’ve also (as mentioned previously), put a 2200uf or 4700uf cap across the output of various supplies and usually a 9(ish) volt zener. It really mattered on a cheap digital reverb pedal I had that I had in the effects loop of an equally cheap and old mixer, lol.

[Dave H]

Yeah, and given that a usable, working SMPS is so far over my engineering capabilities ... its a no-op for me: buy whatever, or build a linear.

You could make a Spyder by using a single 12V DC wall wart (say) and 8 isolated 1W 12V to 9V DC/DC converter modules to break the ground loops then there's no SMPS to design, it just has to be wired up. If the wall wart was SMPS you could even sell it in California

[doctor]

No one should agree with me. I just expressed my opinion both as a pro-audio engineer who designed and manufactured a variety of equipment: pedals, amplifiers, analog and digital effects, etc., and as a guitarist.

And, of course, I did not mean that someone will develop and manufacture the SMPS here. Judging by the level of discussion, here are no specialists with the necessary qualification.

I had in mind to buy ready-made SMPSs for $ 5.00 and not bother.