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the19thbear
Joined: Apr 19, 2007
Posts: 150
Location: denmark
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 Posted: Mon May 27, 2013 4:11 am Post subject:
Elka Wilgamat III External sync |
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Save the image to view it bigger.
The elka wilgamat is one of those "one man band" thingies from 1982. Sounds so corny and cool!
-As you can see in the lower left corner, there is a tempo slider controlling a 555 timer. This goes on via a clock output and goes further down to a CPU that is controlling everything with pulses/gates etc.
Is there any way of midifying this thing? i would love to be able to sync it via midi or even audio pulses.
I already bypassed the 555 and tried to sync it via audio pulses but no luck.
sadly I dont know that much about electronics ( i can read schematics and tell different components from each other etc..)
thanks! |
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the19thbear
Joined: Apr 19, 2007
Posts: 150
Location: denmark
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| Posted: Fri Jun 07, 2013 12:26 pm Post subject:
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anyone?
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the19thbear
Joined: Apr 19, 2007
Posts: 150
Location: denmark
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| Posted: Wed Jun 19, 2013 12:22 pm Post subject:
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| bump |
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the19thbear
Joined: Apr 19, 2007
Posts: 150
Location: denmark
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| Posted: Sun Jan 04, 2015 8:23 am Post subject:
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| bump once more |
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IGR
Joined: Aug 31, 2014
Posts: 19
Location: Brno
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| Posted: Mon Jan 05, 2015 5:05 am Post subject:
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Just try to turn 555 astable to monostable:
-break wire from VR1 wiper to pin 5
-isolate pin 2 from rest of circuit, it will be trig in
-bridge R10 (connect pin 7 to 6)
Guess it coul be done switchable 3*3pole switch. |
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the19thbear
Joined: Apr 19, 2007
Posts: 150
Location: denmark
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| Posted: Mon Jan 05, 2015 5:34 am Post subject:
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Thanks! So what can i then use as an input to trigger the 555? a square pulse? DC?+5volts?
Thanks again:) |
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IGR
Joined: Aug 31, 2014
Posts: 19
Location: Brno
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| Posted: Mon Jan 05, 2015 5:57 am Post subject:
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555 has schmitt trigger input (pin2), it switches at 1/3 U (+5V/3=1,6V),
pulse lenght- time high- remains approximately (22 ms astable/35ms monostable) the same (given by R/C constant), time low should be 0,5ms-
this is lenght of your trig pulse |
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the19thbear
Joined: Apr 19, 2007
Posts: 150
Location: denmark
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| Posted: Mon Jan 05, 2015 6:52 am Post subject:
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so DC. 0-1.6volts?
And length should be 35ms for the pulse? (sorry, i dont understand the differecen between astable/monostable), but i guess my mod will be using monostable? 0 volt length should be 0.5ms.
Is there any standard (like Din sync maybe?) that has that pulse/0volt duration already?
thanks again |
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PHOBoS
Joined: Jan 14, 2010
Posts: 5603
Location: Moon Base
Audio files: 705
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| Posted: Mon Jan 05, 2015 7:24 pm Post subject:
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| the19thbear wrote: | so DC. 0-1.6volts?
And length should be 35ms for the pulse? (sorry, i dont understand the differecen between astable/monostable), but i guess my mod will be using monostable? 0 volt length should be 0.5ms. |
In Astable mode the 555 oscillates which is how it's currently used. (It's actually used as a VCO with the voltage on pin 5 controlling the tempo)
In Monostable mode the 555 output is low untill there is a high to low (inverted) transition on pin2. Then the output will become high
and stays high for a time that is set with a resistor and capacitor attached to pin6/7. Then the output will return to a low state (unless pin 2 is still low).
You could indeed transform it from an astable to monostable with some switching but it's probably easier to add a switch between the output of
the 555 (pin3) and the input of the 7404 (pin1), so you can use an external trigger input. For midi you'd need somekind of MIDI to trigger
converter. For audio you'd need something to turn the signal into a square pulse (pulselength doesn't really seem to matter for this circuit).
Probably a comparator maybe with an extra opamp to boost the audio signal.
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the19thbear
Joined: Apr 19, 2007
Posts: 150
Location: denmark
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| Posted: Tue Jan 06, 2015 12:14 am Post subject:
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| Thanks! |
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