FS: powered bus board PCB

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: lisa, luketeaford, Kent, Joe.

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Wed May 13, 2020 8:53 am

no worries. I learn by being corrected. this bus board would not be as good as it is if KSS did not suggest turning thermals off. I'm learning to take criticism and explain why I did what I did. there are numerous threads where I acted like some smart ass kid. I'm trying to be more professional kind and understanding as I age. this is practice. feel free to point something out because I will likely learn from it or at least practice explaining it.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Thu May 14, 2020 11:28 pm

stocking this in my store now. tomorrow I will add a button for the crimpers and the closed end connectors. those are all in stock.
You do not have the required permissions to view the files attached to this post.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sun May 17, 2020 10:44 am

Image
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Wed Jun 17, 2020 6:12 pm

IMG_20200617_185256404.jpg
IMG_20200617_185520691~2.jpg
There is a 3 month lead time to have these manufactured. Nothing is in stock. There are a few of the other part numbers available in small quantities around the internet. I'm the only one who has these in stock. There is a PCB and a choke etc. About a month from now these go on sale. I have wire crimpers and special heavy duty 5 conductor portable cable in my online store. I also have a load testing setup so I can post ripple specs and thermals. Stay tuned.
IMG_20200604_200039555~2.jpg
IMG_20200604_200156557~2.jpg
You do not have the required permissions to view the files attached to this post.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

Elahrairah
Learning to Wiggle
Posts: 24
Joined: Sat May 02, 2020 12:25 pm

Re: FS: powered bus board PCB

Post by Elahrairah » Wed Jun 17, 2020 9:48 pm

What are these switches in the June 17th post?
I've been working on my own power supply, and learned that standard switches (5A/125VAC) will not survive DC with large capacitive loads. Switching is known to cause miniature arcs internally and the cheap switches welded themselves closed after just a few tries at 20VDC.
And if you still don't have a scope, these stupid things are a lot better than nothing.

edit: tried to post a link there, doesn't seem to be showing, maybe the forums are secure against new users. Search DSO Shell and theyre under $50.

KSS
Super Deluxe Wiggler
Posts: 2519
Joined: Mon Jan 25, 2016 7:28 am

Re: FS: powered bus board PCB

Post by KSS » Wed Jun 17, 2020 11:20 pm

Google snubber. Helps with DC switching. And don't forget a diode if you're dealing with inductive loads

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Thu Jun 18, 2020 10:33 am

The switches are strange run + start switches waterproof for boats. Really nice switches made by Carling. 16A. Part STM2EE-58. The power supply has flyback diodes. I don't anticipate the inductive spike to be that serious with little tiny wire wound resistors. There is no motor. The biggest one is 15R 30W but it only gets loaded to 10W. I'm not actually testing the AC DC converters connected to dummy loads. Each AC DC brick feeds two bus boards. One brick for each rail. I'm testing heat and ripple before and after the bus board so I can determine if these components are suitable for modular synthesizers. Worst case is 150mV at the output of the brick before all the filtering. I expect to get that down to maybe 10mV. Really just guessing. Could be 8mv or 15mV based on the math. Could be 2mV who knows. Then after the regulators that should be more like 0.5mV or 0.2mV.

I did buy an owon scope and a better meter with temp probe. I will definitely provide specs so people can decide based on merit not marketing.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

KSS
Super Deluxe Wiggler
Posts: 2519
Joined: Mon Jan 25, 2016 7:28 am

Re: FS: powered bus board PCB

Post by KSS » Thu Jun 18, 2020 3:36 pm

@EYG
my post was aimed at Elahrairah's post just above it, and his stated problems with it.

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Thu Jun 18, 2020 6:27 pm

These are $0.70 no worries. Even if you put snubbers on a small switch, I'm not really in favor of that. I really absolutely hate broken switches. I always get spendy switches. I realize that crappy power supply testing jigs can start a fire. Much respect for Carling switches.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Wed Jun 24, 2020 6:49 am

before I do something stupid, I thought I would ask the engineers. can I use a common mode choke with one coil wired backwards as a differential mode choke? obviously I can but the question is should I? this choke has all the specs I want, the DC resistance, the low permeability core, tuned to attenuate 10KHz, enough power rating.

https://www.mouser.com/ProductDetail/80-SSR10V-30016

I can turn it 45 degrees in the PCB layout.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Thu Jun 25, 2020 8:39 am

I switched to a slightly larger choke from KEMET. then I wired it for differential mode. off the top of my head, an impedance increase x5 at 65KHz = ~-15dB PSRR? I like to spend the money to make nice power supplies. these are very limited right now. it takes two units to make a 6U system. I am keeping 2 of 10. 4 lucky people or one person building a massive 19inch 1U rack power supply will have an oppurtunity to buy this before they are all gone.
PCBPREVIEW.gif
You do not have the required permissions to view the files attached to this post.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sat Jun 27, 2020 8:14 am

I would really like some feedback good bad indifferent anything. it makes me nervous sending out an order for PCB's for a power supply that has not been looked over by an electrical engineer.
PCBPREVIEW2.gif
mornsunschem.gif
You do not have the required permissions to view the files attached to this post.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
revtor
Dialing it in..
Posts: 1666
Joined: Sat Nov 29, 2008 10:31 am
Location: North Jerz

Re: FS: powered bus board PCB

Post by revtor » Sat Jun 27, 2020 8:24 am

(Cough) Paul schreiber pateron $25 level will discuss yur circuits (cough)
Fellow North Jersey Synthaholic

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sat Jun 27, 2020 8:31 am

revtor wrote:
Sat Jun 27, 2020 8:24 am
(Cough) Paul schreiber pateron $25 level (cough)
but I only get two a year. I have much much larger things to take advantage of Paul's offer to proof read. likely I will need to fix and give it to him again for a second revision. that project has thousands of dollars depending on success. this project will make no money and I will probably kill it off when I go back to school. Paul is a valuable limited resource like the spice. spice must flow. this project is like a sandworm. it keeps coming back to eat my bank account.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
latigid on
Ultra Wiggler
Posts: 931
Joined: Fri Oct 25, 2013 11:05 am

Re: FS: powered bus board PCB

Post by latigid on » Sat Jun 27, 2020 8:42 am

Talking of SPICE, did you try to simulate it?

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sat Jun 27, 2020 8:55 am

I don't have a model of this special choke or a recording of the waveshape of the ripple produced my the AC-DC module. the core material is proprietary to kemet. this choke is %100 unique. I have learned techniques from old books to do analysis with pencil and paper. I know the estimated PSRR based on the impedance vs frequency from the datasheet. my question is if you can wire a common mode choke in differential mode or is this some stupid idea that will not work. it seems like it will work but I don't think the computer has that level of general AI yet to answer the question. also, this is a combination choke that also has two differential mode inductors built in. in practice there are not multiple inductors, I think it is done by carefully controlled stray inductance to bring back some differential mode choke properties to what is primarily a common mode choke. my question is if I reverse the primary mode of operation, does that make it better for my application?
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
latigid on
Ultra Wiggler
Posts: 931
Joined: Fri Oct 25, 2013 11:05 am

Re: FS: powered bus board PCB

Post by latigid on » Sat Jun 27, 2020 9:09 am

Still, it's something that you could take an empirical guess at, knowing the frequency of the DC-DC and noise specs.

Inductors aren't my forte. But what happens when an AC signal goes through a transformer? It couples to the other winding and induces a current on the other side. Would a common-mode choke not induce symmetrical currents on both windings? So when the peak is MAX, the two phases cancel, vice-versa at MIN, because the windings are travelling in opposite directions?

So your idea of wiring one phase backwards would get some sort of phase shift based on the frequency of the noise and the dimensions of the choke.

No idea really :)

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sat Jun 27, 2020 11:59 am

I did the calculations already 65KHz 150mA ripple. @ 2A load. Using impedance at 65KHz, per side. As far as I understand it, a differential mode choke is a common mode choke with one coil connected out of phase. This cancels differential mode noise like the 65KHz SMPS ripple. I completely lose the common mode attention though. Like I said earlier, stray inductance makes it work both ways. Even without coupling, inductors increase the impedance of common mode noise. This is where it goes into hand wavy ask an engineer. That is the limit of my understanding.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

Elahrairah
Learning to Wiggle
Posts: 24
Joined: Sat May 02, 2020 12:25 pm

Re: FS: powered bus board PCB

Post by Elahrairah » Sat Jun 27, 2020 1:01 pm

EATyourGUITAR wrote:
Sat Jun 27, 2020 8:14 am
I would really like some feedback good bad indifferent anything. it makes me nervous sending out an order for PCB's for a power supply that has not been looked over by an electrical engineer.
PCBPREVIEW2.gif
mornsunschem.gif
Can you give a little more space between these components? That diode looks like the kind that will get warm.
You do not have the required permissions to view the files attached to this post.

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sat Jun 27, 2020 2:08 pm

there are no diodes. there is one electrolytic cap. one 1/4w 64K pulldown resistor that trims 15v to 16v. one common mode choke wired for differential mode.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Thu Jul 09, 2020 9:23 am

the choke part number
SSRH24NH-50041

question: is 0.75mm diameter copper conductor ok for 2A 16v continuous load? this is between 20AWG and 21AWG. I got some advice from an engineer who told me that the original part I was intending to use was too small. all these ratings are for AC. however, I think I can still use this PCB if I spec a 5A choke. 0.75mm diameter copper can probably handle 2A DC with no more than a 20C temp rise. DC impedance is 0.030 Ohms. AC impedance at 65KHz is 3K but I was told since the core is already saturated with DC then the inductance goes down by a factor of 1/100. if this is true then the 3K becomes 30 Ohms. if that is true then the DC Z vs AC Z through the inductor for each leg is 1:2. keeping this in mind, the temperature rise is a bit unknown. the actual ripple rejection is also unknown. could be -6db could be -60db. the only thing I know for a fact is that there is a 2000uF there that does a really good job at filtering power noise.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

socom93
Common Wiggler
Posts: 51
Joined: Sun Mar 24, 2019 1:19 pm
Location: France

Re: FS: powered bus board PCB

Post by socom93 » Sat Jul 11, 2020 9:15 am

EATyourGUITAR wrote:
Sat Jun 27, 2020 8:55 am
I don't have a model of this special choke or a recording of the waveshape of the ripple produced my the AC-DC module. the core material is proprietary to kemet. this choke is %100 unique. I have learned techniques from old books to do analysis with pencil and paper. I know the estimated PSRR based on the impedance vs frequency from the datasheet. my question is if you can wire a common mode choke in differential mode or is this some stupid idea that will not work. it seems like it will work but I don't think the computer has that level of general AI yet to answer the question. also, this is a combination choke that also has two differential mode inductors built in. in practice there are not multiple inductors, I think it is done by carefully controlled stray inductance to bring back some differential mode choke properties to what is primarily a common mode choke. my question is if I reverse the primary mode of operation, does that make it better for my application?
It's not stupid and you are right to ask yourself the question but in you application using it as a differential mode would make it only usefull above MHz and i don't know if it's what you want here.

20awg is really not much for 2 Amp DC.

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sat Jul 11, 2020 9:56 am

Ok so I was thinking about that. I could put the scope before and after the choke on the prototype to see how much attenuation I get from the choke. 20awg is not great but it all depends on the temp rise @ 20 minutes @ 2A continuous. I can live with a 20C rise. If it is more than 20C, I am going to place 5W ceramic resistors where the choke would be. I really don't want to throw away 50 PCB's.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sat Jul 11, 2020 9:58 am

There are sometimes really fast rise times on a 65KHz SMPS that may have harmonics in the MHz???
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 4892
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: FS: powered bus board PCB

Post by EATyourGUITAR » Sat Jul 11, 2020 2:12 pm

what do you think of this DC choke?
EH28-3.0-02-9M0-X


280-CR5-240-RC
or these ceramic load resistors? the datasheet says 50C rise @ %20 load 5W -> 1W = 240 Ohms per leg. 0.5v drop each resistor. the power supply can be trimmed to 16.7V. estimating a 0.4v drop through the cable. that brings 15.3v directly to the input of each bus board.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

Post Reply

Return to “Music Tech DIY”