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MBSeqv4 Power Requirements

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Hey guys, I was wondering what you all do to power your Seq?

Right now I am using just the USB from the computer, and I have the jumper from PA9->5V. I currently have Wilba's front panel, with 2 LCDs, Midi IO, and I just added a DOUT for CV gates, clock, etc. When I measure the 5V on the STM324F, it is down to 4.45v.. Next up, I am addin an AOUT_NG. Is the USB Power from the computer enough? I guess the solution would be to provide wal-wart power via the USB Mini, remove the jumper, and then I could still connect the computer via the USB micro for MIOS Studio functions. 

Is that the way to go?

Thanks, Justin

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5v from USB is fine, but for the a_out you need + and - 12v. (at the least for the A_out-ng)

Currently I am using a DIY eurorack powersupply for testing the a_outng.

But I am considering this ones: found this small dc-dc conversters mentioned by Oliver Pichenette @MI ' Traco Power TMR1-1222 or TRN1-1222'

Should be able to deliver enought current.  And its tiny so you can build it in to your midi box.

Alternatively I am considering to take power directly from a eurorack synth. connecting using a dsub 25.

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Thanks - good points guys. Right now, I just finished assembling my Aout, except I didn't catch that all the resistors are 1%, so I am waiting on a few more resistors.

I'm using a DIY skiff to hold the synth, and it has a power supply with it. I was planning on grabbing the +/- 12 from that power. Rowan's eurorack breakout panels for the CV outs/gates/triggers looks great. 

At the moment, I can't imagine setting up with the MBSeq very far from the rack, so I don't plan to make the line driver, but we'll see how much I like the eurorack stuff.

Now I have to finish soldering up the synth, and I can start making some noise! I have already been messing with midi and my MBSid, and the sequencer is so cool. I can just turn on the robo/hum settings and listen to randomly generated stuff. very cool.

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  • 1 month later...

I have used the murata dc to dc converters. They are isolated and can take 5v in to -/+12 out. They are generally 1A but you can get them in 3A or higher packages. I have mostly used them to build isolated laser, rdm and dmx controllers. They come in allsorts of voltage options both on the input and output including +/- output. The non isolated ones are a bit cheaper. Either would work great to power the analog module. I used one in my midibox sid build. They run cool too unless you short the outputs. They do take a short for a bit but will let the smoke out after a while. Lot less heat, space and weight to think about than a transformer and 78xx regulators. Should be much cheaper than a dual voltage transformer if you are considering that.

The Dlink 7 port fast charging hubs or Linksys DUB H7 are really good too if you have several devices to power by usb. They both have a 3A power supply...  and should work anywhere in the world as the plugs are 100 -250v. Not as nice looking as the one linked above but they put out a lot of available power if you need it.

Currently I am just using a 1a usb cell phone charger cube. I like the ones that the usb plugs on the top as they make power strip management much easier. I have oleds, wilba's front panel, tpd and midi io. I have a 2c midi too but it currently is not connected. I am under 500ma and the 1A cell phone cubes work great. If I had back lit LCD or a 16x16 BLM the current draw would be a good bit higher.


I also used one of these so not to plug directly into the core:


I might go with one of these now I did not see them at the time:


The usb B is just a lot more sturdy connector.


Edited by gerald.wert
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Thanks guys,

I ended up going with a wired meanwell 5V supply. I pull the + and - 12v for the AOUT from my eurorack powersupply. Everything is working great now. I used to get some pulsing of the backlight LEDs on the LCDs, but now it is rock solid.


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  • 2 weeks later...

Just to add some more info to this thread...

I tested the line drivers in my configuration (STFM32F4 core, 2 x blue LCD, Wilba panel, line driver transmitter, line driver receiver, TPD, BLM16x4 and 2 x MIDI I/O) and the power consumption peaked at 750 mA. So these things really add to the overall power consumption!


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Yes back lit LCD are very power hungry! normally around 300ma each on a 2x40 some will peak over 500 ma on startup. Better have a heat sink on that regulator!

oled 2x40 are normally under 50ma each... makes a huge difference on
Thermal power dissipation. They are a lot sharper too just not cheaper.

Edited by gerald.wert
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5 hours ago, beautyofdecay_ said:

My reference was to the line drivers.
When I added them, power consumption went up with about 300mA. The TPD and BLM16x4 were connected to the receiver side of the line drivers. I didn't expect them to be so power hungry... :confused:

How many LEDs !?! ... don't know the limiting resistor value at these built but 300mA is 30 LEDs @ 10mA, easy to get !



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