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Thread: pedal power supply question about RG's article

  1. #36
    Don't forget the joker g1's Avatar
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    I would have to say that 'curt, judgemental, and pontificant' is often how non-first language or translations often appear. Especially for technical issues.
    I would beg anyone here who doubts doctor's sincerity to click on his user name and select 'view user posts'. On no occasion has he been less than helpful, and many times more behind the scenes via PM.

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  2. #37
    Bent Member Chuck H's Avatar
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    Quote Originally Posted by g1 View Post
    I would have to say that 'curt, judgemental, and pontificant' is often how non-first language or translations often appear. Especially for technical issues.
    I would beg anyone here who doubts doctor's sincerity to click on his user name and select 'view user posts'. On no occasion has he been less than helpful, and many times more behind the scenes via PM.
    Ok. I don't have a problem meeting halfway on cultural differences. It's not always a language barrier. More often it's a posture that is inherently offensive between one culture and another. I think I've been moderate. With a hedge that the problem might not be everyone other than the person in question. Not much more to say about that.

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    "Never bet your life on somebody else doing their job." SoulFetish's good friend

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  3. #38
    Old Timer Leo_Gnardo's Avatar
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    Quote Originally Posted by g1 View Post
    I would beg anyone here who doubts doctor's sincerity to click on his user name and select 'view user posts'. On no occasion has he been less than helpful, and many times more behind the scenes via PM.
    Second that! doctor has often supplied rare & obscure schematics here. Although none of them were items I needed, I appreciate his contributions to MEF and consider him a very valuable member.

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    Enjoy. Every. Sandwich.

  4. #39
    Supporting Member Jazz P Bass's Avatar
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    Yeah, I don't get it.
    Flogging the Doc is uncalled for.

    The Doc has been awful helpful supplying obscure documents.

    From what I read all he said was "welcome to the real world."
    SMPS is here to stay.

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  5. #40
    Bent Member Chuck H's Avatar
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    Quote Originally Posted by Jazz P Bass View Post
    Yeah, I don't get it.
    Flogging the Doc is uncalled for.

    The Doc has been awful helpful supplying obscure documents.

    From what I read all he said was "welcome to the real world."
    SMPS is here to stay.
    I'm not "flogging the doc". I admit to having a little fun with the winky face though. And I'm sorry if I have encouraged further negativity from other members. I've acknowledged that his position is valid. And I honestly hope that any SMPS issues from the earlier power supplies that used them is actually worked out and is now a non issue. It's just too soon to tell really. Short story...

    A few years ago I was in the market for a new cordless drill driver. my last one was a DeWalt 12V NiCad that was an absolute NAIL of a tool for over fifteen years. In the months prior to purchasing I heard a lot of contractors complaining about the reliability of the batteries in their new Li Ion tools. They would fail prematurely due to charging inconsistencies, sometimes freezing temps were involved (that happens to work trucks here) and the new batteries were expensive. So I went with NiCad again on the premise that it's 50yo tech and caused no problems for me in the past. Here I am a few years later and one of my two NiCad batteries has failed (and I did treat it properly) and all the same contractors are using Li Ion tools without issue. I have serious buyers remorse because my tool is comparably heavy and the crappy batteries they supplied with it are failing anyway. My point:

    Probably SMPS power supplies have worked out the pedal incompatibility issue? I don't know. My instincts still tell me to go with known, reliable tech. But this has bitten me on the @$$ before and I might be a dinosaur.

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    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  6. #41
    Supporting Member John_H's Avatar
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    I surfed across these power supplies on ebay a few weeks ago. I didn't expect much for less than $20, but figured I could at least use the steel housing to build something suitable. What I got was a pleasant surprise. It's a nice unit. Much more than I expected. There wasn't much information in the ad. I plugged up to 7 devices into it, and it maintained a constant 8.96v. It's quieter than anything I've ever had. I ordered another for a spare.
    https://www.ebay.com/itm/Dinosaur-Po...ffb1aa|iid%3A1

    Here's a gut shot. My only complaint is that I wish the cables had a 90* plug on one end.
    Click image for larger version. 

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  7. #42
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    Fr good reasons, more and more pedals include a protection diode in the power path to prevent folks using wallwarts with the "wrong" polarity. Once upon a time, when folks might use any old AC-to-DC adapter, there was a chance they might select one with the wrong polarity (outside ground) and fry the pedal. Then manufacturers started insisting you use THEIR adapters. Eventually folks started powering pedalboards with multi-outlet power "bricks". But once folks were incorporating PNP germanium transistor pedals into their pedalboards, power-brick makers had to include reverse-polarity outputs, which meant there was still a risk of the user running a cable from the "wrong" output to the pedal if they weren't paying attention.

    So, there is still good reason for pedal manufacturers to include protection against "wrong" power polarity.

    There are two ways to do so. One is to have a diode to ground, so that anything above the diode's forward voltage goes to ground, leaving the pedal powered by only 500mv or so of the "wrong" voltage (not enough to fry anything). The other is to insert a diode in series with the power supply so that the circuit is never fed anything other than the "right" polarity. The caveat with that method is that it subtracts one diode's worth of voltage. So, if the diode removes a half volt, then the circuit will still get 9v if the power source is 9.6V or thereabouts. Not that the circuit will die if it's less than that. But various circuits may well be tuned/calibrated in anticipation of 9v.

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  8. #43
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    Yeah. Daisy chaining is fine for an all-analog pedalboard...providing all pedals involved have the same power-plug polarity. The one exception might be instances where a pedal uses a charge pump to goose the voltage from 9V to double or triple. IN those instances, there might be some heterodyning of the clock in the charge-pump and the clocks in the switching power supply. That's based on theory, not experience.

    RG Keen and I have been buddies for over 25 years. As the designer of the One-Spot, he pays very close attention to any complaints or problems that end-users have had, and finds solutions via either production changes to the One-Spot, or posted user advisories.

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  9. #44
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    There's "toast" and there's off-spec.

    Last year I repaired a buddy's Diamond Memory Lane pedal that had an annoying whine. I corresponded with their tech person, trying to pin down the source of the whine, thinking it was a misadjusted trimmer. It wasn't until I mentioned that the whine didn't start until after about 10-15 minutes of use that he remembered the likely source. He told me that in an early run of the pedals, they had received a shipment of voltage regulators (I think they were 9V) whose heat fin was much thinner than "regulation size" (pardon the pun). He sent me a picture of what it would look like and sure enough, that was the culprit. I pulled it, installed a regulator with normal-thickness heat fin, and the problem went away for good. The pedal used three of the 3-pin voltage regulators, with all three relying on the heat fins to dissipate any heat they might produce. The offending one lacked the heat fin mass to do the job, such that after a little while, it would overheat; not enough to be damaged or damage anything else, but enough to be well off-spec in its performance.

    The upshot here is that it is not enough to simply add up the current requirements of the pedals used and have that total come out to less than the current rating of the supply. There should be a margin of safety incorporated such that the power supply is not stressed. Keep in mind that most wallwarts and power-bricks are essentially sealed, with no way for heat to escape. Again, the stress may not jeopardize the lifespan of the supply or pedals being powered. But it may result in the power not being on-spec.

    There is rarely anything wrong with using a PS rated for much more current than the pedals require. That's why one can use a One-Spot - rated for 1.7A - with a pedalboard that only needs 75ma for everything on it.

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  10. #45
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    Thanks to those who say good words about me, but I do not need protection.

    I have long noticed such a fact. If a professional is told that he does not know something, he will try to study this topic. If these words are heard by a non-professional who has a high opinion of himself (but without big reasons), then he begins to be rude. Because essentially he cannot answer. This is ridiculous and I do not pay attention to personal attacks.
    I should note that professionalism is not equal to education. I am familiar with great professionals who do not have a higher education. Although higher education is, of course, very desirable. Knowledge cannot be superfluous.

    Now to the point. Most manufacturers of the audio/electro musical equipment do not produce now linear PSUs/adapters at all, only SMPSUs.
    There are two points that make life easier for SMPS users. Modern SMPSs have a low level of noise (conductive and radiated emission) and modern devices (including pedals) have a weak susceptibility to external interference (conductive and radiated immunity). All modern audio equipment meets the requirements of the standard EN55103-1 "Electromagnetic compatibility. Product family standard for audio, video, audio-visual and entertainment lighting control apparatus for professional use".

    Problems may arise with old devices, in the development of which no one even thought about the level of immunity. This problem (if it exists) must be solved precisely for such a device. As a rule, the installation of a ferrite cores on the connecting cables (power, input and output) is sufficient.

    I am writing this for all those who want to solve such a problem with minimal expenditure of money, labor and time.

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    Last edited by doctor; 01-12-2019 at 05:59 PM.

  11. #46
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    Quote Originally Posted by Mark Hammer View Post
    Fr good reasons, more and more pedals include a protection diode in the power path to prevent folks using wallwarts with the "wrong" polarity. Once upon a time, when folks might use any old AC-to-DC adapter, there was a chance they might select one with the wrong polarity (outside ground) and fry the pedal. Then manufacturers started insisting you use THEIR adapters. Eventually folks started powering pedalboards with multi-outlet power "bricks". But once folks were incorporating PNP germanium transistor pedals into their pedalboards, power-brick makers had to include reverse-polarity outputs, which meant there was still a risk of the user running a cable from the "wrong" output to the pedal if they weren't paying attention.

    So, there is still good reason for pedal manufacturers to include protection against "wrong" power polarity.

    There are two ways to do so. One is to have a diode to ground, so that anything above the diode's forward voltage goes to ground, leaving the pedal powered by only 500mv or so of the "wrong" voltage (not enough to fry anything). The other is to insert a diode in series with the power supply so that the circuit is never fed anything other than the "right" polarity. The caveat with that method is that it subtracts one diode's worth of voltage. So, if the diode removes a half volt, then the circuit will still get 9v if the power source is 9.6V or thereabouts. Not that the circuit will die if it's less than that. But various circuits may well be tuned/calibrated in anticipation of 9v.
    Cool thanks Mark, thinking about this. So far, I only have pedals I built myself (I gave away all my 'vintage' MXR pedals to my brother a few years back) so the risk of wiring something wrong and hooking up the wrong polarity is a lot bigger I think.

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  12. #47
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    One is to have a diode to ground, so that anything above the diode's forward voltage goes to ground, leaving the pedal powered by only 500mv or so of the "wrong" voltage (not enough to fry anything).
    Please do not use this option without adding a fuse. As the diode presents a short to wrong polarity, both PS and protection diode may get destroyed without a fuse.

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  13. #48
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    I''ve been scanning Ebay for weeks now, looking for a better quality regulator board. I bought a few last year, couple dollars each I think 2.00 or so, that included the board, a few caps, diodes, LED, regulator and WAAYYY too small heat sink. I bought some heat sinks from Mouser, was able to drill the board out a bit, and glue in heat sinks, something like 4 times the height and many times the mass. They still get hot but not so hot you can't touch them.

    I found some boards with "Audiowind" name, seen the name a few times before. They cost more, but look a little better quality. Bigger caps, and heat sink, layout a little better (at least what I can tell).

    Assembled and (at least they say) tested:
    https://www.ebay.com/itm/9V-DC-Volta...igpv:rk:8:pf:0

    If I bought the PCB and parts, could build for 8 bucks I think. I like to solder and fiddle with stuff, but if this board is all done, maybe just go with that. The heat sink is like 10x better than the ~2.00 boards I got last year. Have no idea about the regulator chip itself.

    Still not so close on transformers. The thread started out looking for suitable transformers, but looks like not many made these days, so many discontinued (I won't comment on the newer sw***hing PS thing, seems to stir up a lot of bad blood )

    What Id like to do, I think, is get say 4 or 5 of these reg boards, mount them inside a nice case with a vent screen on the back. Put a transformer for each reg, then put a switch, fuse, LED on top and dc jacks on the front. Total cost is more than, say, the Pedal Power ISO5 (that is smaller, lighter, factory built, tested etc), but, heck I can build this!!!

    Are these transformers OK:
    https://www.jameco.com/webapp/wcs/st...gDrillDownView

    Pricey to ship, but 8 bucks is cheaper than I found elsewhere.

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