z2amiller
Active member
I mostly got into building pedals to make stuff for my guitar playing nephews. The best I can say for myself is "well, I OWN a guitar".
This year at Christmas, the younger of the two nephews was like, "Gee, Uncle @z2amiller, these sure are great but what I really need
is a way to power a bunch of them at once". That got me thinking about making my own power supply. But I'm not a musician and
don't really know what's out there, or what kind of features would be interesting.
I've been noodling around a bit. I think what would make cool features would be:
* PedalPCB-standard 125B size.
* Using a USB-C power supply as the input. (requiring USB-PD) Everyone has or can find a 65W USB-C adapter/cable. I don't think I've seen anyone else doing this but it seems like a no-brainer.
* [Maybe] having some of the ports be switchable to 18V. Or permanently 18V. The downside of switchable 18V ports as I see it is accidentally plugging a 9V pedal into that port if there's not a lot of feedback that it's 18V (e.g. making the plug+cable yellow or red or something which you can do if it's permanent). 18V is easy because USB-PD can deliver 20V.
* [Probably] Using isolated outputs. I hear that guitar players pay money for these. I can do isolated outputs but it cuts down on the density, I can get fewer ports in there since the components to do isolation are quite a bit larger (transformers, etc). I was wondering, though, does isolated power even matter when the first thing you do is chain the ground of a bunch of pedals together with 1/4" cables?
* [Stretch] Finding a way to make the power outputs be top-mounted. I was actually thinking about ethernet cable connections, since power-over-ethernet can deliver some tens of watts, why not branch that out into a bunch of 9V barrel plugs? You can do 4 per cable and there's room in a 125B for 4 of them on top. And you can get fancy right-angle cables. But that might mean a lot of custom cable making (and if you've read some of my other posts you might know how much I hate soldering wires to things, especially other wires). Easier would be pre-made barrel jack<->barrel jack connectors with jacks along each side. Is there some kind of multi-connector cable that'd be better than this?
* [Extra Extra] I could probably do something fancy like current monitoring per port, but I was struggling with finding displays that would be dense enough,
7 segment delays don't get small enough that I could find, but there's always fancy OLED displays and stuff. This wouldn't work with stacked boards though, not enough vertical room - and now it's adding a microcontroller, too. I'll probably skip this.
I think that with isolated 9V/18V power, I could probably fit 12 jacks into a 125B, with two boards vertically stacked.
The isolated power version is a lot more expensive. Component cost-per-port is about $2. With a non-isolated version I could probably get by with a handful of shared buck converters and get to 16 ports on a single board pretty easy - component cost-per-port is probably 50 cents. But it might require another stacked board on top just to handle the density anyway if using the standard barrel jack connectors, or figure out a way to do top-mounted power delivery.
I was thinking I could probably do a super-cheap one as well, using USB-PD negotiating 9V and just letting the USB adapter do all of the work for voltage conversion. (And maybe throw some filtering in there). Negotiating 9V you can get up to 27W which is whatever like 30 100mA pedals. Something like this could fit in a 1590A (or even an altoids tin) and use daisy-chain barrel plugs.
I think even kinda-commercializing something like this would be Complicated since it's dealing with power supplies, so I'd probably share the whole project when I'm done if there's interest. I'd be really interested to hear from the community if anyone's tried anything like this before, or has some kind of wishlist on what would make a good power supply.
This year at Christmas, the younger of the two nephews was like, "Gee, Uncle @z2amiller, these sure are great but what I really need
is a way to power a bunch of them at once". That got me thinking about making my own power supply. But I'm not a musician and
don't really know what's out there, or what kind of features would be interesting.
I've been noodling around a bit. I think what would make cool features would be:
* PedalPCB-standard 125B size.
* Using a USB-C power supply as the input. (requiring USB-PD) Everyone has or can find a 65W USB-C adapter/cable. I don't think I've seen anyone else doing this but it seems like a no-brainer.
* [Maybe] having some of the ports be switchable to 18V. Or permanently 18V. The downside of switchable 18V ports as I see it is accidentally plugging a 9V pedal into that port if there's not a lot of feedback that it's 18V (e.g. making the plug+cable yellow or red or something which you can do if it's permanent). 18V is easy because USB-PD can deliver 20V.
* [Probably] Using isolated outputs. I hear that guitar players pay money for these. I can do isolated outputs but it cuts down on the density, I can get fewer ports in there since the components to do isolation are quite a bit larger (transformers, etc). I was wondering, though, does isolated power even matter when the first thing you do is chain the ground of a bunch of pedals together with 1/4" cables?
* [Stretch] Finding a way to make the power outputs be top-mounted. I was actually thinking about ethernet cable connections, since power-over-ethernet can deliver some tens of watts, why not branch that out into a bunch of 9V barrel plugs? You can do 4 per cable and there's room in a 125B for 4 of them on top. And you can get fancy right-angle cables. But that might mean a lot of custom cable making (and if you've read some of my other posts you might know how much I hate soldering wires to things, especially other wires). Easier would be pre-made barrel jack<->barrel jack connectors with jacks along each side. Is there some kind of multi-connector cable that'd be better than this?
* [Extra Extra] I could probably do something fancy like current monitoring per port, but I was struggling with finding displays that would be dense enough,
7 segment delays don't get small enough that I could find, but there's always fancy OLED displays and stuff. This wouldn't work with stacked boards though, not enough vertical room - and now it's adding a microcontroller, too. I'll probably skip this.
I think that with isolated 9V/18V power, I could probably fit 12 jacks into a 125B, with two boards vertically stacked.
The isolated power version is a lot more expensive. Component cost-per-port is about $2. With a non-isolated version I could probably get by with a handful of shared buck converters and get to 16 ports on a single board pretty easy - component cost-per-port is probably 50 cents. But it might require another stacked board on top just to handle the density anyway if using the standard barrel jack connectors, or figure out a way to do top-mounted power delivery.
I was thinking I could probably do a super-cheap one as well, using USB-PD negotiating 9V and just letting the USB adapter do all of the work for voltage conversion. (And maybe throw some filtering in there). Negotiating 9V you can get up to 27W which is whatever like 30 100mA pedals. Something like this could fit in a 1590A (or even an altoids tin) and use daisy-chain barrel plugs.
I think even kinda-commercializing something like this would be Complicated since it's dealing with power supplies, so I'd probably share the whole project when I'm done if there's interest. I'd be really interested to hear from the community if anyone's tried anything like this before, or has some kind of wishlist on what would make a good power supply.
