Power supply from directly from MIDI cable

[emastyle]

Hello, is there a way to power supply the pic core module (simply used to trigger midi event from 3 switches and without display) directly from MIDI data cable?

I have a MIDI SOLUTION midi Merger 2x2 (based on PIC) wich not requires external power suppply!!!

How is it possible?

Thank you

Emanuele

[Altitude]

No, that only works with super low current devices. I've seen devices based on pic12s but the pic18 draws too much current (I dont know if even a pic16 would cut it)

Edited January 5, 2011 by Altitude

[Davo]

When I saw this post, I thought you were going to suggest running current through the two pins that MIDI doesn't use. It's interesting and full of potential trouble.

[emastyle]

When I saw this post, I thought you were going to suggest running current through the two pins that MIDI doesn't use. It's interesting and full of potential trouble.

I thought to use a standard midi cable, supplying the power to pic usign the "20mA current loop".

Maybe using a low power microPIC I can do this...

[m00dawg]

I thought to use a standard midi cable, supplying the power to pic usign the "20mA current loop".

Maybe using a low power microPIC I can do this...

Though not a PIC, the offerings from TI are both inexpensive and super super low powered. I forget the name of the kit but it was like $5.00 and in its lowest active state, it draws less current than the natural resistance of a CR032 battery (!). Obviously for the chip to do anything interesting it draws more but might be something to look at maybe.

[Altitude]

Here is a good example of a midi bus powered PIC12 device (midi to sync24 converter):

http://www.colinfraser.com/m2d/m2d.htm

[nILS]

I still think this is a horribly evil thing to do.

[emastyle]

Due to my simple design (I need only to send midi CC by 3 switches), with a little battery, using a 16f88 and managing sleep/wakeup interrupt modes could be an option. What do you think?

Edited January 6, 2011 by emastyle

[technobreath]

I totally agree with nils here. The concept means trouble. To build a linear psu is veeeery simple and the physical space required is a next to nothing. Why create an insufficient troublemakng solution when its so simple?

I understand this can look like an interesting idea, and you could always make something like a power injector like power over ethernet uses and that way the amps wont be limited by other than the cable gauge, but it will make the equipment incompatible with standards and it is more. work than just building the simple psu that thotsten has in the schematics. If u want more juice than this you could replace the 7805 with a higher amp rated 7805. The ones i use is rated 2 amps. Just mount a hefty heatsink to it and you shouls have more than enough for just about any midibox project. Just remember to use a transformer wich can deliver enough amps. I have some transformers salvaged from old alarm panels at work, they are fused on 1,5 amp, and should be mooore than enough. The reason i use higher rated regulators is becaise thats what i had.