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Midimerger power supply from MIDI


stefanovic
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Hi all,

 

I'm interested in building a MIDImerger. I can build some electronics, but I am not _that_ knowledgeable in electronics.

 

AFAIU, the MIDImerger needs an external power supply. I was wondering if this was really necessary. Wouldn't it be possible to get the power from MIDI? As in this product:

 

http://www.midisolutions.com/prodmrg.htm

http://www.midisolutions.com/faqs.htm#Power

 

Cheers !

 

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You could check the datasheet of the PIC16(L)F88 for power consumption and then see how much power you can draw from MIDI. However, I would not rely on a merger without power supply - it is a failure prone system, as it will depend on the equipment you use it with whether it will work or not.

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hi stefanovic,

 

i dont think, that it would be better to get the power from midi. its an isolated connection. theres no ground from the transmitter to the receiver and no power from either device. i dont even believe, that your midi-solutions-merger works at all. the list of unsupported devices is quite long. yes, maybe some devices will work, but that would be by "accident"...

 

for a start i suggest you this easy one without mcu:

 

http://www.sonelec-musique.com/images/electronique_midi_merger_001.gif

 

if you want a better one read here:

 

 

sry. didnt find further information on ucapps.de, but "something like that" is definetely a better solution for a midi-merger in my opinion. if you dont feel "that knowledgeable in electronics" look out for this:

 

http://www.doepfer.de/mmr_e.htm

 

yes, i know, its sold out, but maybe you can find it somewhere on the 2nd hand market... :D

 

kind regards,

mOnO

 

edit:

 

here is something "made in uk":

 

http://www.thomann.de/gb/kenton_midi_merge.htm

Edited by mono
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@ilmenator @mono: Thanks for you answers.

 

My plan would be to merge the input coming from a Behringer BCR2000 and a keyboard (GEM promega 3) to output into a Mutable Instruments Ambika...

If I just pick the power from midi instead of an external power, what would be the risk? That it just does not work with that particular devices? Or it would not work for whatever other reasons?

 

Cheers!

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for a start i suggest you this easy one without mcu:

 

http://www.sonelec-musique.com/images/electronique_midi_merger_001.gif

 

I'd suggest that you immediately forget about this one - it will corrupt your MIDI data as soon as both devices connected to the IN port send data at the same time. Who on earth "designs" such things, without even considering the nature of the MIDI protocol?

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My plan would be to merge the input coming from a Behringer BCR2000 and a keyboard (GEM promega 3) to output into a Mutable Instruments Ambika...

If I just pick the power from midi instead of an external power, what would be the risk? That it just does not work with that particular devices? Or it would not work for whatever other reasons?

There is no risk apart from the risk that it might not work. However, as the Ambika is DIY you could always include the merger in the Ambika itself and power it from there. Take a look at the MIDIbox range of mergers here.

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...in case of the bcr2000 you can forget about the diy-midi-merger! just connect your bcr-out to the ambika and your keyboard to the bcr-in. if you select midi-mode 1-3 on your bcr it will merge your data. no need for seperate (diy-) hardware!

 

@ilmenator: the link is from a french guy. google found it for me. i suppose, if you send the odd midi-bytes every few minutes/hours, the "simple" midi-merger will work a treat. otherwise it will fail, because it will "shuffle" the midi-bytes around...:D

 

mOnO

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There is no risk apart from the risk that it might not work. However, as the Ambika is DIY you could always include the merger in the Ambika itself and power it from there. Take a look at the MIDIbox range of mergers here.

 

Yes, it's a good idea, I will consider it.

 

Looking at the MIDImerger page, I see that many components can be left out (power supply of course, but also leds and optocouplers). Even for the simplest circuit, I guess it would be safer though to leave the diodes at the output of the midi in plugs?

 

Another question: there is a small circuit with two caps (C1 & C2) on this schematic: http://ucapps.de/midimerger/midimerger_pic16f88.pdf. What are they used for?

 

Maybe those questions are not appropriate to this forum, as they seem related to basics in electronics, do not feel obligated to answer them...

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...d1 (for each optocoupler ?) is there to protect the optocoupler from anything what could damage it from your midi-in. c1 should be next to the output of the voltage regulator (ic3) to give you better stabilisation and c2 should be connected to your pic (vdd/vss). its called a decoupling cap:

 

http://en.wikipedia.org/wiki/Decoupling_capacitor

 

most of the times you dont need it, but on a pcb i wouldnt leave them out. just in case something doesnt work as expected...

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...in case of the bcr2000 you can forget about the diy-midi-merger! just connect your bcr-out to the ambika and your keyboard to the bcr-in. if you select midi-mode 1-3 on your bcr it will merge your data. no need for seperate (diy-) hardware!

 

Well actually I want the BCR2000 to control the Ambika, but also the Ambika to refresh value on the BCR2000.

My setup is:

BCR2000 out -> in Ambika

Ambika out -> in BCR2000

 

with BCR2000 set to S4 mode to avoid midi loops.

 

I have tweaked the Ambika firmware to receive an 'all controllers request' sysex, and the Ambika sends all current CCs value to the BCR2000.

Of course there is no midi in plug left, hence the need for a merger (keyboard + bcr2000 out) to send note on/off to the Ambika and actually play something with it instead of just control it :-P

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My plan would be to merge the input coming from a Behringer BCR2000 and a keyboard (GEM promega 3) to output into a Mutable Instruments Ambika...

 

your last posting sounds different to your first, doesnt it ? but anyway, i would try the pic-based midi-merger as the easiest and cheapest solution. if you cant do that, just try to avoid your feedback-loop from the ambika. it has only 8 controls. dont know what they are for though, but whats the point of controlling one device with 2 sorts of controllers ? just stick to your bcr2000 and it should be alright. especially you could setup the bcr for the ambika in multiple presets and switch between them, instead of using the 8 controls from the ambika itself....

 

mOnO

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your last posting sounds different to your first, doesnt it ?

 

what do you mean? In which way it is different?

if it's about my skills: I know how to code, but I'm really bad at electronics, I can build an ambika, but sometimes I ask dummy questions (see my remark about the diodes :-/)

 

but anyway, i would try the pic-based midi-merger as the easiest and cheapest solution. if you cant do that, just try to avoid your feedback-loop from the ambika. it has only 8 controls. dont know what they are for though, but whats the point of controlling one device with 2 sorts of controllers ? just stick to your bcr2000 and it should be alright. especially you could setup the bcr for the ambika in multiple presets and switch between them, instead of using the 8 controls from the ambika itself....

 

well this requires a deeper explanation. The Ambika is a multi-timbral synthesizer. I'd like to configure the BCR2000 so that a preset corresponds to one 'timber', which means that each time I change the preset on the BCR2000 (say I want to control timbre #2 instead of timber #1), then the BCR asks to the Ambika the values for that timber (#2), the Ambika answers and updates the new preset on the BCR accordingly...

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The Ambika project is based on an ATmega 644, which has two internal UARTs (= 2 MIDI IN and 2 MIDI OUT)

Maybe the option for a second MIDI IN is not prepared on the PCB, but it shouldn't be so difficult to add one (and to enable the second UART in the firmware) - just ask the Author of this project.

 

Best Regards, Thorsten.

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I am not 100% sure, but I think I remember that the program memory for the Ambika is absolutely maxed out (or was it on the Shruthi?). Also, Olivier has made it clear several times that he is not going to invest any significant amount of time into the Ambika anymore. It seems Mutable Instruments, his company, has moved on to other, more profitable items, leaving the DIY world mostly behind.

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