[sdiy] MIDI VOL PEDAL with no micro??

[Dan Snazelle]

well heck

thanks a lot!

i cant be sure if he will try it or not but i think once i draw that out on paper and start thinking about it, well to put it lightly, its the kind of thing I love to check out !!



Sent from my iPhone

> On Feb 8, 2014, at 2:44 PM, "Roman Sowa" <modular at go2.pl> wrote:
> 
> Get any parallel output 8-bit ADC, feed its output to the inputs of serial shift register, like HC597, then add a few more HC597 to set the rest of the message.
> Next thing is clock source - either crystal one, or piezo resonator, or even plain RC clock, as you need clock stability of about 3%.
> Next step - simple movement detection circuit made with opamps (you
> asked for them) - gain of about 20, then integrator, and 2 comparators
> to detect +/- 0.5V crossing. Pot movement detected this way latches the shift registers and triggers  clock burst to the chain of HC597. You may also use digial comparator and latches for last sent value, but that's quite a few chips more.
> 
> You need to send this sequence, including start/stop bits:
> 
> 0 1 0 1 1 0 0 0 0 1 0 0 0 0 0 0 1 1 1 1 0 0 <7 MSB from ADC> 1
> which in human hex language means "B0 07 <pot>", this is channel volume in channel 1.
> 
> 30 bits total, so 4x HC597
> 
> A lot more complex circuitry than any example with uC, but also a lot bigger chance to learn something while building it, and pure fun of making it without any firmware.
> 
> Roman
> 
> W dniu 2014-02-08 20:16, Dan Snazelle pisze:
>> is it possible to create a MIDI volume pedal with nothing but an
>> optocoupler, opamps, cmos and passives?
>> 
>> 
>> i ask because i have a friend who wants to make one himself
>> 
>> id just use an AVR with an opto and a pot based pedal.... but i
>> thought it might be fun to go the other route
>> 
>> 
>> are CC messages complex? i wouldnt dare try this with SYSEX but i
>> thought a CC pedal might be within the realm of possibility!
>> 
>> 
>> thanks
>> 
>> 
>> Sent from my iPhone _______________________________________________
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