The Abacus only needs a modest 60 mA current draw from 12v and -12v (no need for 5V)
I’ve been investigating this in light of the fact that Behringer appear to be shipping bits and bobs and i need to make a call … stick/twist on the pre-order !
A psu or case can both easily double the cost of a module respectively … I found real world use of a dual voltage Mean Well DC converter (from DKM10 range … )
I don’t need to consider the 5v input option (no need for 5v out) for this skiff (so the DKM10 E(5-9v in)-12(+/- 12 out) isn’t of interest - but when i got thinking of how bonkers it was to put in a 12v source into DKM10A(9-18v in)-12(+/- 12 out) to get 12 and -12v out i did a bit more digging and found this possibility which i might like to sanity check here before trying(frying) with two Elektron PSUs (looking with a voltmeter first)
In a nutshell, assuming the PSUs are isolated (between input and output) i should be able to short the + of one PSU(A) to the - of the other PSU(B) thus giving on A a relative voltage of -12v at its - ‘pin’ compared to the now 0v at its + pin (still some 12v higher than at the - pin)
These aren’t dedicated oscillators, so nothing to get mega precious about in terms of psu spec precision - obviously i’ll need some means to attach the power to the rear of teh modules but i imagine strategically placed regular jumper cable type connectors will be all that’s needed
A zero cost way to test the waters without committing to a powered rack with room to fill (or none)
Not much visibility on the Behringer gear in progress topic, this is in any case a broader general query about dipping the toes into Eurorack gear without making it easy to expand.
I need to test some incoming modules without spending too much in case it doesn’t work out.
haha you’re still on this hunt? I guess cost is relative, but to me the time you’ve spent researching it probably outweighs the financial cost of buying a cheap case
Time is money friend!
I’m not sure how safely you’d get that +12/-12v to a rail that you can get into a ribbon cable - from a DIY perspective anyway. I’m no Electrocutionist. Can you just wire it directly into a ribbon cable? Or would you need some kind of buffer between the two? I assume bus-boards must be doing something…
I think that part of the job is ensuring that it’s clean and steady - anything that’s voltage controlled I assume is susceptible to shenanigans if your power isn’t ‘clean’.
Otherwise jam them cables in and see what happens. If you break the module though you’d mitigate any cost saving you were hoping to achieve. There is a definite risk/reward factor here.
If you’re in the UK I could send you a 4MS case to use for dipping those toes, if that’s helpful. Wouldn’t scratch that DIY itch though
Thanks for the offer, but the DIY itch serves many purposes. I have an abundance of 12v power supplies and any outlay for a ‘proper’ euro case inevitably leads to an optimisation resulting in more outlay. Doing it this way is a low risk and fun way to use what I have and keep options open. Interfacing with ribbon cables won’t slow me down, I possibly have some anyway and or male/female header pins to fake it, this is a one time only install.
It’s an outlier query for sure, but it may help one other person out. The questioner in one of those links was presumably doing the same thing for a Eurorack installation where they fried their proper power supply. It had a 5v requirement, which I don’t just now. I have an insane amount of power supply adaptors, so using those is sensible, plus it’s a chance to make a nice wee box as a project.
Makes sense! Yea 5v is quite a rare requirement, the only module I know of that I’ve ever owned that uses it is a USB output module, which is very specifically a 5v power outlet.
I won’t pretend to know why it exists or what it’s for beyond that.
DC voltage can be creatively ‘misused’ (* at your own risk) to differential create a -12v from the Ground of a secondary psu if you tie its +ve to the negative of the first (thus it’s zero), the relative difference of 12v remains, so the ground signal is now -12v
Works a treat, i’ll tinker with the design for the final skiff, got some chunky capacitors to smooth any ripples and i’ll fine tune the voltages which are very close anyway
Only consider such endeavours if you are methodical and do so at your own risk, i have no need for 5v, so it’s relatively simple (there are 10 connectors as opposed to 16 on these boards, 2 + , 2 - , 6 gnd - but only three unique contacts, so i just used a 3 core ribbon and aligned as appropriate (red being -12))
yeah yeah … Beurora Borealis, Beuro de Change, Beurder MeinSkiff, Ferris Beuro’s Day Off and other such riffage on Budget Euro … last laugh is all mine as I Jam Econo
Total specific outlay on the skiff/power in shot is about £1.30 for the 4 IDC connectors, everything else up-cycled
… EIGHT !
