# Powering breadboards for bipolar circuits with a -12V rail **URL:** \ **Category:** DIY STUFF\ **Created:** [October 8, 2023, 2:51pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597 "2023-10-08T14:51:31Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![AriaSalvatrice](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/ariasalvatrice/32/28804_2.png) [@AriaSalvatrice](https://lookmumnocomputer.discourse.group/u/AriaSalvatrice)\ **Post date:** [October 8, 2023, 2:51pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/1 "2023-10-08T14:51:31Z")
Breadboards are meant to be used with unipolar power supplies, and after quite a few close calls plugging in things wrong, I decided to standardize my setup and build myself a little power module. Maybe it will inspire you, so I’ll give it its own thread, plus let’s hear how others are powering their setup. So, the thing I made: ![](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/b/c/bcc0883197a1dd8fb05e820842b210c3f1403405.jpeg) It’s two standards cheapo breadboards fastened together with adhesive in the back. For the rails, I used POSCA acrylic paint markers, this stuff isn’t cheap but lasts long and sticks to everything. Those are the kind of breadboards where the two lateral halves of the power rail don’t connect, so there’s a little wire to connect them (you won’t see it well on the photo). For the color scheme, I picked red, yellow, and blue, because it’s the least ambiguous to me: does black mean negative or ground? Depends who you ask. Yellow seems more accepted to mean ground rather than negative. For the layout, I matched the one I use for my custom prototype boards: ![](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/7/2/72e7fa015dd622596fe8c3eef57f3526d8046097.jpeg) > **[GitHub - AriaSalvatrice/synth-protoboard](https://github.com/ariaSalvatrice/synth-protoboard/)** > > Contribute to AriaSalvatrice/synth-protoboard development by creating an account on GitHub. Regarding the power module itself, it’s pretty self-explanatory: ![](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/2/d/2d93c791cadd1225f063f9f724753695ae65cba1.jpeg) ![](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/2/a/2a30821ee8ba540a436259dbcde5c4148b8673de.jpeg) To note: - I cut this protoboard in half using a Dremel and a heavy-duty cutoff wheel. Don’t attempt without a respirator! - I fastened both halves using pin headers. - The pin headers that connect to the rails should be placed on the breadboard and soldered while on the breadboard, to ensure perfect alignment. - I expect it to incur a fair amount of mechanical stress over its service life, so I added a generous helping of hot glue everywhere. It’s not really necessary. - There’s a 10µF capacitor on each rail, since it pretty much comes standard on every single build. - There’s reverse polarity protection diodes, since I always use them, this way I won’t have nasty surprises with the voltage drop they cause. - I didn’t add a switch as I prefer to cut off the entire supply, and it could be a bit mechanically unstable to add it to the board. You really don’t need a schematic, but hey, why not: ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/1/f/1f9ebd561127098d2e69018f7278a649a1812595.png) (And before you ask: the wire tray in the first pic is also my Art. Thanks for asking! [Get the STL here](https://www.printables.com/model/587695-tileable-breadboard-wire-tray)) ---
**Author:** ![TimMJN](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/timmjn/32/15227_2.png) [@TimMJN](https://lookmumnocomputer.discourse.group/u/TimMJN)\ **Post date:** [October 8, 2023, 3:08pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/2 "2023-10-08T15:08:43Z")
> [@AriaSalvatrice](#): > > For the color scheme, I picked red, yellow, and blue, because it’s the least ambiguous to me: does black mean negative or ground? Depends who you ask. Yellow seems more accepted to mean ground rather than negative. Nitpicking, but I don’t think I’ve ever seen yellow used as ground, neither have I seen black to mean anything but ground in a bipolar situation. I, for one, use yellow for +5v. Anyway, nifty! ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [October 8, 2023, 3:28pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/3 "2023-10-08T15:28:09Z")
I’m also a black = ground person, after having heard @fredrik’s acerbic views on the subject, and blue for -12 V. I’m not married to a convention for 5 V, but I guess I’ve used yellow. As for rail order, I’ve been known to use MI’s [Breadboard Friends](https://pichenettes.github.io/mutable-instruments-diy-archive/bbf/), so I use their convention: ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/a/d/ad09bcc1c5a6a9fbd04bc743992d59e2ae397ec6.png) (They’re red/black/blue fans too.) ---
**Author:** ![AriaSalvatrice](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/ariasalvatrice/32/28804_2.png) [@AriaSalvatrice](https://lookmumnocomputer.discourse.group/u/AriaSalvatrice)\ **Post date:** [October 8, 2023, 3:31pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/4 "2023-10-08T15:31:17Z")
The colors are very much a culture-dependent and an application-dependent thing anyway. As far as I’m concerned, in a DIY build, the correct color is the one where you’ll never plug in things wrong. ---
**Author:** ![mightywombat](https://avatars.discourse-cdn.com/v4/letter/m/839c29/32.png) [@mightywombat](https://lookmumnocomputer.discourse.group/u/mightywombat)\ **Post date:** [October 8, 2023, 6:18pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/6 "2023-10-08T18:18:39Z")
> [@AriaSalvatrice](#): > > As far as I’m concerned, in a DIY build, the correct color is the one where you’ll never plug in things wrong. I’ve been looking at power supplies lately and they all seem to use the red=positive, black=negative, green=ground color schema. I’m a black=ground, green=negative person myself, but luckily you can swap/replace binding posts. That said, yeah, whatever your brain says when you look at the color, go with that, otherwise you end up having to re-train yourself and that just leads to frustration and burned out ICs. I think I ended up using blue for 5v and yellow for 3v3 when I replaced the posts on my ATX PSU adapter board. ---
**Author:** ![Gasboss775](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/gasboss775/32/26802_2.png) [@Gasboss775](https://lookmumnocomputer.discourse.group/u/Gasboss775)\ **Post date:** [October 8, 2023, 6:39pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/7 "2023-10-08T18:39:58Z")
Typically I go with: RED; +12V, GREEN; GND, BLUE; -12V Sometimes if Im incorporating single rail circuitry using the RED=+12V, BLACK=GND I will use these colours plus BLUE for -12V Recently I used Red/Yellow/Blue when I had no green wire, seemed like the most obvious substitute. Oddly the ATX power supplies use yellow for +12V For +5V I’ve used orange or pink ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [October 8, 2023, 7:57pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/8 "2023-10-08T19:57:12Z")
In the US, DC wiring (for solar power, batteries, etc.) has red for +V, white for grounded neutral, black for -V, and green, bare, or yellow stripe on green for protective ground. And of course in other countries it’s different — brown for +V, etc. > **[Electrical Wiring Color Codes for AC & DC - NEC & IEC](https://www.electricaltechnology.org/2020/07/electrical-wiring-color-codes-nec-iec.html)** > > NEC Wiring Color Codes for AC and DC in US & Canada. IEC Wiring Color Codes for AC & DC in UK & EU China & Russia Cable Color Codes. India, PAK, SA, IL Code But that’s only relevant if that’s what you learned for wiring solar panels and you don’t want to try to retrain your brain for building synths. ---
**Author:** ![Gasboss775](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/gasboss775/32/26802_2.png) [@Gasboss775](https://lookmumnocomputer.discourse.group/u/Gasboss775)\ **Post date:** [October 9, 2023, 12:51am UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/9 "2023-10-09T00:51:51Z")
I used to be perplexed by the US/Canada colour schemes, but I read this little aid: Black = Death 》》Live White = Neutral colour 》》Neutral Green = Nature 》》Earth / Ground Is interesting to see India etc still use our (UK) old colour scheme R, Y, Blu, Black ---
**Author:** ![Soundbrigade](https://avatars.discourse-cdn.com/v4/letter/s/4af34b/32.png) [@Soundbrigade](https://lookmumnocomputer.discourse.group/u/Soundbrigade)\ **Post date:** [October 12, 2023, 8:30pm UTC](https://lookmumnocomputer.discourse.group/t/powering-breadboards-for-bipolar-circuits-with-a-12v-rail/6597/10 "2023-10-12T20:30:07Z")
I also find it annoying that there’s no thrid rail for -12V, but I will look into your project. Btw, no LED for 0V?? 🙄