January 6, 2019 at 4:41 pm #3677AnonymousInactive
This is my first post about my first build. While I am building the D’Lay board as a stompbox, my comments, are not specifically about my build. My comments are about external power. There are two options, 9V internal battery and external 9V (e.g. wall wart). In review of the connection drawings I noted that external 9V power (typically supplied on a 5.5 / 2.1mm barrel connector) was on the outside of the barrel not on the “tip” (inside the barrel). This surprised me. I assumed power would be on the “tip” (inside the barrel) so it would be kept away from the outside world where most things are grounded.
It also went against the wiring for all of my other 9V devices. I have a device that adapts a 9V battery to a 5.5/2.1 mm barrel jack. It is wired with the 9V signal connected to the “tip”. This absolutely cannot be used with stompbox devices. Also, external power supplies must also follow this standard lest the stompbox and/or the power supply be destroyed. In my junk box I have an old RS 9V supply (linear) that follows the stompbox standard, All of the newer switching supplies have the power at the “tip”.
This brings me to my point. I did not see anything on the website that spelled this out. Perhaps I missed it, but as this is the kind of thing that can lead to a serious problem, I suggest making it more visible. In an ideal world this information would be a section in the build document with a (humorous?) title of “Power it Right or How not to Blow Up your Project Immediately”. Also, I would update the wiring diagrams to include a quick note / drawing that DC power is provided on the outside of the barrel.
As this is my first post, I want to thank you for hosting this forum and providing a way for people to get into analog audio electronics. If my comments are erroneous or out-of-line, please allow me to apologize in advance.
ACVJanuary 6, 2019 at 4:57 pm #3678BarryKeymaster
Hello and welcome.
There is a ton of information in the GUIDES SECTION of our forum for clarification on most anything.
Here is a great link with a great explanation. Note all of our circuits require a power supply with negative (-) polarity and the few PNP Fuzz circuits we carry incorporate a charge pump to reverse it. This is common to most DIY Pedal Projects with some exceptions of course. We also utilize a protection diode in the majority of our circuits where power connects. That said I appreciate what you are saying however just note that each of our 80 unique projects require negative polarity.January 6, 2019 at 5:12 pm #3679wilkie1Moderator
Welcome to the forum! I completely understand your confusion regarding th external power for pedals. It seemed counter-intuitive to me as well.
But the INDUSTRY STANDARD for effects pedals is to use a CENTER NEGATIVE 2.1 mm DC jack and plug. (I didn’t make this rule, I just know that it is the widely accepted way to do it.) If you peruse the specifications for commercial effects pedals, you will see that this is correct.
It is true that you can find many DC power supplies that use a center positive configuration. These are usually found in use with other commercial devices.
Thanks for inquiring!
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