PNMini - Positive-Negative Power Supply Module for Makers - Page 1
Forum section: electronics / general

author: wfsuper
author_rank: Newbie
timestamp: March 16, 2014, 01:13:08 am
content: Hello, makers!I just launched a project. It's a positive/negative power supply module for makers. It uses an innovative circuitry so that positive and negative supply can be integrated to one 3 pin module.It's an idea I had for a long time and I almost put it on every DIY projects I designed. It's very easy to use. One module supports both positive and negative output.Check it out:https://www.kickstarter.com/projects/pnmini/pnmini-positive-negative-power-supply-module-for-mI would like to share this idea with you and contribute to the open hardware community.Thanks!

author: CanadianAvenger
author_rank: Regular Contributor
timestamp: March 16, 2014, 02:55:50 am
content: You've already broken cardinal rule #1 for crowdsourcing a product... DO NOT USE FLEXIBLE FUNDING! This is not a charity fundraiser... how do you expect to fulfill your commitments if you fall short? Unlike fixed funding, with flexible funding you're still on the hook, no matter how little you raise.

author: MatCat
author_rank: Frequent Contributor
timestamp: March 16, 2014, 03:10:47 am
content: $300 for 200 boards? I just got a run of 600 boards roughly the same size (and oddly enough very similar use) for $150...

author: wfsuper
author_rank: Newbie
timestamp: March 16, 2014, 03:17:57 am
content: Quote from: MatCat on March 16, 2014, 03:10:47 amThat's the quote I got. Where did you order yours for such a low price?

author: wfsuper
author_rank: Newbie
timestamp: March 16, 2014, 03:20:43 am
content: Quote from: CanadianAvenger on March 16, 2014, 02:55:50 amThanks for the suggestion. It's my first time doing this kind of things. Any more comments and suggestions?

author: MatCat
author_rank: Frequent Contributor
timestamp: March 16, 2014, 03:29:01 am
content: Quote from: wfsuper on March 16, 2014, 03:17:57 amElecrow doing v-scored panelized boards.

author: wfsuper
author_rank: Newbie
timestamp: March 16, 2014, 03:35:07 am
content: Quote from: MatCat on March 16, 2014, 03:29:01 amThanks! Did you sell them on ebay?

author: MatCat
author_rank: Frequent Contributor
timestamp: March 16, 2014, 03:36:23 am
content: Quote from: wfsuper on March 16, 2014, 03:35:07 amNo my products are sold via vendors.

author: wfsuper
author_rank: Newbie
timestamp: March 16, 2014, 03:45:13 am
content: Quote from: MatCat on March 16, 2014, 03:36:23 amYeah, that should be my next step.

author: sleemanj
author_rank: Super Contributor
timestamp: March 16, 2014, 05:03:33 am
content: Including the tab, your board is about 20mm by 24mm, 4 of those would fit in a typical 50x50 10 board service from all the various cheap pcb factories.Your PCB costs may be higher because you have that tab which means a simple v-score separation probably won't work, it needs to be routed out, just make the board rectangular then it's just a v-score grid.

author: mariush
author_rank: Super Contributor
timestamp: March 16, 2014, 12:04:33 pm
content: You can make a 350x250 mm panel at Eurocircuits for $240 with 15day delivery... with 24x20mm boards and 2 mm in both directions allowed for break routing, you could squeeze about 13x11 boards on a panel.. 143 boards. 2 panels (286 boards) for 380 dollars, 5 panels (~715 boards) for 540$ and from there it gets cheaper, for example 30 panels (4300 boards) for 1200$ (40$ per panel).It's still not as cheap as that 600 boards for 150$ quote but it's a bit cheaper than yours.ps. v-cut only needs about 0.45mm clearance so if you can tweak the board to 24x19 "square" you can probably fit 14 x 12 boards or 168 boards per panel

author: Scarionn
author_rank: Contributor
timestamp: May 25, 2014, 08:43:52 pm
content: What DC converter are you using in this project?

author: jadew
author_rank: Frequent Contributor
timestamp: May 27, 2014, 12:58:32 am
content: How is it different from this one?http://www.ebay.co.uk/itm/5X-LM2596s-DC-DC-Buck-Converter-Adjustable-Step-Down-Module-Voltage-Regulator-/251457946719That one can do both positive and negative output, just like yours, by simply switching GND with Vout. It's also 18 times cheaper.

author: mariush
author_rank: Super Contributor
timestamp: May 27, 2014, 01:03:09 am
content: Well let's see... much lower efficiency overall due to the lower switching frequency, possibly fake buck regulator IC (or recycled from other boards) or it's actually a chinese clone chip used, probably needs much higher input voltages compared to this pnmini IC (i think it's at least 5v in to output 3v for the lm2***), not tuned (inductor and diodes chosen for wide input voltage range, so there's lower than possible efficiency in some cases)

author: jadew
author_rank: Frequent Contributor
timestamp: May 27, 2014, 01:28:38 am
content: Quote from: mariush on May 27, 2014, 01:03:09 amAs it happens I have one of those on my bench, I didn't get it from that seller (I actually got it cheaper).Looks like you're right regarding efficiency (if his plots are correct), with 7V on the input I only get 60% efficiency for 3.3V @ 100mA.Edit: and btw, I could draw 100mA @ 4V with 5V on the input, so 3.3V should be doable with less than 5V.

author: PlainName
author_rank: Super Contributor
timestamp: June 10, 2014, 12:13:17 pm
content: I backed this and my perk just dropped through the door. This is an excellent project delivering exactly what was expected, and the backup support (documentation, CAD stuff, etc) is excellent too. Very happy

author: con-f-use
author_rank: Unknown
timestamp: June 27, 2014, 04:11:01 pm
content: Quote from: dunkemhigh on June 10, 2014, 12:13:17 pmAgreed.I selected the DIY 0.5A version for 10$. What I got was the DIY version I selected plus the assembled 0.5A and 2A version. >20$ worth of stuff for my 10$. Don't know if that was a mistake but I'm very happy.

author: MacAttak
author_rank: Unknown
timestamp: June 27, 2014, 05:45:22 pm
content: Still waiting on mine. They appear to have had a problem with accounting or planning, and ran out of the initial batch of parts. I'm in no hurry to get them though, too busy with other projects (and my day job) right now to do anything with them.