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external power supply case connectors?
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author external power supply case connectors?
EATyourGUITAR
I am building a mixed system of +12v/-12v/0v and +15v/-15v/0v with an external power supply that is my bench power supply. it has 5A per rail but the ripple is shit 100mV P-P. I want 14AWG conductors sending 19V DC for each rail from the external bench supply down a 6FT cable into the case for the mixed system. they will share a common conductor for 0v. I decided I would just put LM317 and LM337 on each row bus board to drop down from 19v to 15v or 12v.

some people use speakon? XLR? nana? I really don't think I want banana. I did that last time. not good in the dark. I found this connector and I wanted to see if you think this is a waste of money or if I should use speakon or something else

https://www.amazon.com/4-0mm2-IEC-309-32A-ROJ/dp/B012UHGT32

https://www.ebay.com/itm/IEC309-2-32A-220-240V-2P-E-IP44-3-P-Connector -w-Waterproof-Coupler-Socket/231169680130

as a side note. I want to minimize noise in the spring reverb. that is why I am using an external supply. do you think the 100mv AC is going to matter with my spring reverb return line? should I put huge caps on the 19V lines? where do I put the caps? ferrites?
Graham Hinton
EATyourGUITAR wrote:
I want 14AWG conductors sending 19V DC for each rail from the external bench supply down a 6FT cable into the case for the mixed system. they will share a common conductor for 0v.


Have a look at the ITT Trident range. You can get tin (don't use gold) 16awg solder contacts (to avoid the crimp tool, although crimping is better) and use multiple wires in a rectangular or circular block.

Don't ground the incoming 0V, bring the mains ground in separately and connect to the 0V after the regulators and anything else that needs grounding.

Quote:
some people use speakon? XLR? nana? I really don't think I want banana. I did that last time. not good in the dark. I found this connector and I wanted to see if you think this is a waste of money or if I should use speakon or something else

https://www.amazon.com/4-0mm2-IEC-309-32A-ROJ/dp/B012UHGT32

https://www.ebay.com/itm/IEC309-2-32A-220-240V-2P-E-IP44-3-P-Connector -w-Waterproof-Coupler-Socket/231169680130


Definitely not, that is a 240V mains connector commonly used on stages. In general, don't use a connector that is standardised for a different purpose, especially non-power or mains.

Quote:

as a side note. I want to minimize noise in the spring reverb. that is why I am using an external supply. do you think the 100mv AC is going to matter with my spring reverb return line?


You are going to have much larger ac signals nearer the reverb. Treat the reverb pickup like a balanced microphone.

Quote:

should I put huge caps on the 19V lines? where do I put the caps? ferrites?


Next to the regulators.
EATyourGUITAR
Thank you for help. I understand what you are saying about bring mains earth directly into the chassis as chassis ground and connecting it to the synth 0v. However this is a PVC case. The only thing metal is the vector mounting rails for the 3U. Should I still earth my subracks? There is no mains in the case at all. Only DC to DC inside. I plan to close off the spring reverb with a metal plate and mount the metal plate on some vibration dampening standoffs. Nothing that goes through the case though. Would it be smarter to eliminate the possible ariel of earth and just ground the subracks to internal 0V DC as a RF shield?
555x555
I’ve used these:
https://www.mouser.com/ProductDetail/523-T3302550
https://www.mouser.com/ProductDetail/523-T3301551

Note you have to buy the pins separately. They have a relatively low contact resistance and good crimp connectors. They say 18awg, but I’ve crimped 14. Four pins, two for ground. You could use three or six, just don’t use five since that’s midi.

The better way to do it would be to use military spec circular connectors which are specifically designed to take higher gage wire, but that wasn’t going to work for me as these won’t mount flush (the *female* case mount mounts flush—for me, this was the half of the case that was supplying power. In general it’s good practice to use female connectors for the supplying side and male for the receiving, as this lowers the chance of accidentally shorting something; so those are the parts I linked).

There’s also some rectangular connectors that are specifically meant for power distro - look at Molex’s website. I think these are mostly meant for “internal” wiring, though, and don’t look as fancy.
wackelpeter
Maybe connectors like this make sense?

https://www.reichelt.de/steckbare-schraubklemme-6-pol-rm-5-mm-0-rnd-20 5-00159-p170386.html?&trstct=pol_2

has 6 Poles, cable can be thick as 3mm² (AWG12 if i see that correct i the table on Wiki)... can be mounted on stripboard with 5mm width between each pin... Polarity can't be reversed... Only tricky thing would be mounting the jack stable in your case...

They come along with more poles as far as i see too... When using 6 poles for each PSU out you would have 2 for 15+, 2 for gnd and 2 for 15- and you could either make a second for the 12Volts or maybe just use one with more poles, to avoid putting the 12 into the 15 or vice versa...

But unfortunately they only seem to have them with up to 10 poles...

https://www.reichelt.de/terminalblock-10-pin-horizontal-delock-65960-p 259464.html?&trstct=pol_1

but yeah with 3mm² thick cables perhaps you could get away with just one six-pole and use it for all the rails...
555x555
555x555 wrote:
I’ve used these:
https://www.mouser.com/ProductDetail/523-T3302550
https://www.mouser.com/ProductDetail/523-T3301551

Note you have to buy the pins separately. They have a relatively low contact resistance and good crimp connectors. They say 18awg, but I’ve crimped 14. Four pins, two for ground. You could use three or six, just don’t use five since that’s midi.

The better way to do it would be to use military spec circular connectors which are specifically designed to take higher gage wire...


Now that I’m thinking about it, I’m remembering that it was a bit of a pain to get that higher gage wire crimped, as the crimped part of the pin itself fits into the pin housing. I think I had to shave off a few strands. Anyway, it’s doable, but maybe better to use mil spec connectors.
EATyourGUITAR
per Graham's suggestion I made a mouser cart with the appropriate part numbers

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=6bec d52e40

555x555 wrote:
I’ve used these:
https://www.mouser.com/ProductDetail/523-T3302550
https://www.mouser.com/ProductDetail/523-T3301551


I like this!

wackelpeter wrote:
Maybe connectors like this make sense?

https://www.reichelt.de/steckbare-schraubklemme-6-pol-rm-5-mm-0-rnd-20 5-00159-p170386.html?&trstct=pol_2

has 6 Poles, cable can be thick as 3mm² (AWG12 if i see that correct i the table on Wiki)... can be mounted on stripboard with 5mm width between each pin... Polarity can't be reversed... Only tricky thing would be mounting the jack stable in your case...

They come along with more poles as far as i see too... When using 6 poles for each PSU out you would have 2 for 15+, 2 for gnd and 2 for 15- and you could either make a second for the 12Volts or maybe just use one with more poles, to avoid putting the 12 into the 15 or vice versa...

But unfortunately they only seem to have them with up to 10 poles...

https://www.reichelt.de/terminalblock-10-pin-horizontal-delock-65960-p 259464.html?&trstct=pol_1

but yeah with 3mm² thick cables perhaps you could get away with just one six-pole and use it for all the rails...


not exactly what I am looking for
EATyourGUITAR
I also have samples of this on the way to protect the plastic connector on the case.

http://www.rafhdwe.com/catalog/round-internal-handles-inch/8062-632-ss



notice the handle on the side that protects panel mounted components from impact during transportation. this is where I got the idea from.
seank
came here to make this same topic so i figured i might as well chime in with my question.

i'm swapping my intellijel tps80w boards and meanwell 90w psu's for genus modu LIBB's and L-1 linear psu's (one for each of my 6u 104hp cases). my cases do not have enough room to house the psu's so i am building external enclosures for them and i want to find the right connector and wire for the job. i only need 4-pin (+/-12v and two ground) but i would like to use 12-14awg wire. any suggestions?

am i missing anything crucial?
lacsap
seank wrote:
i only need 4-pin (+/-12v and two ground) but i would like to use 12-14awg wire. any suggestions?


I'd also recommend 4pin Din M12 connectors. They are the defacto industry standart to connect sensors and actuators. Sturdy compact and interlocking. They come in two version for their interlocking mechanism (type A or B) just make sure you get matching ones.

If you need to connect bigger wires you can always go for M18 or M23...

Alternatively you can go for 4 Pin XLR. It's larger though than a M12 connector and could be confused with DMX connectors...
seank
thank you! i was actually looking at 4-pole speakon because they can handle up to 10awg wire and they don't need separate genders for the panel mount connectors.

https://www.redco.com/Neutrik-NL4MP-ST.html

https://www.redco.com/Neutrik-NL4FX.html

i just need to get a nice 12awg 4-conductor bundled wire and i think i'm good?

would this work?

https://www.redco.com/Redco-12-4.html
Graham Hinton
EATyourGUITAR wrote:
I understand what you are saying about bring mains earth directly into the chassis as chassis ground and connecting it to the synth 0v. However this is a PVC case. The only thing metal is the vector mounting rails for the 3U. Should I still earth my subracks?


You should still earth your 0V and not through cables carrying currents.

Quote:

There is no mains in the case at all. Only DC to DC inside.


Regardless, your 0V needs a reference and if it did become live through a connection to something faulty, through the PSU or a patch lead, that will force a fuse or breaker to go and you can't be electrocuted holding a patch cable.

Quote:

Would it be smarter to eliminate the possible ariel of earth and just ground the subracks to internal 0V DC as a RF shield?


No. It won't be a shield unless it is fully enclosed anyway. The aerials are your patch lead screens not the earth wire. The third use of earth (after safety and reference) is to discharge induced charges, including RF. By connecting your rack (a small body) electrically to earth (a very large body) the charges are distributed evenly, i.e. mainly in the planet, so they flow away and you don't get pops when connecting.

555x555 wrote:
I’ve used these:
https://www.mouser.com/ProductDetail/523-T3302550
https://www.mouser.com/ProductDetail/523-T3301551


Those are just industrial versions of DIN connectors like the MIDI type. Definitely even more unsuitable for power than XLRs.

seank wrote:
am i missing anything crucial?


Yes, you and everyone else are missing the actual resistance between the PSU and the distribution. This is the most crucial part of a power supply system where common impedance coupling occurs and unless you have remote sensing you need a lot of cable to get this a low enough resistance. I normally run one 10awg/6mm2 cable per rail per foot per amp and another for the return. So if your PSU is six feet away and supplies 2A that is 24 large cables for +/-12V and another 12 if you have +5V. That will work out so expensive that you might as well buy an industrial remote sensing PSU.
EyG was talking about an external connection pre-regulator, but you are talking about post regulator which is not a good idea.
seank
thanks for the help, graham. my psu's are about one foot away from my cases, do you have a suggestion for bundled 4-conductor wire? the speakon connectors can accommodate up to 10awg wire.
Graham Hinton
seank wrote:
do you have a suggestion for bundled 4-conductor wire?


Use discrete wires and put a pliosil sleeve over the bundle, with adhesive lined heatshrink on the ends. Like this:



This cable was for powering a small external skiff and shows a 19-pin Trident Ringlock connector and a gland the other end to avoid the resistance of another set of contacts.
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