Small pulse generator?

Discussion in 'The Projects Forum' started by GRNDPNDR, Mar 11, 2012.

  1. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    I'm looking for some information on how to construct a device that will do the following things to allow me to test a drum brain module for it's various hit ranges.

    send out a short AC pulse
    allow fine control of pulse voltage from 100mV - 8V
    allow multiple pulses to be sent in succession (emulating a drum roll)
    allow control over speed of pulses sent out (I.E. 1 pulse/sec, 2 pulses/sec etc)

    I don't have enough knowledge of electronics to actually design this type of device myself, and I'm not sure if schematics exist for this exact type of thing because if they do I haven't been able to locate them yet.

    What I want to achieve is to press a button, and get a pulse of a specific voltage. I need to be able to know what voltage the pulse actually is though.
     
  2. crutschow

    Expert

    Mar 14, 2008
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    If you want this all to be controlled by buttons, then a microprocessor controlling a D/A converter will likely be the easiest way to go. You could use a keypad to input pulse speed, duration, no. of pulses, and amplitude, and an LCD display module to show the settings.

    But obviously this requires someone with knowledge of electronic design and microprocessor programming. So, if you are not up to that, then you will need help from someone who is. Seems unlikely that you will find anything already designed that fits your requirements.
     
    Last edited: Mar 11, 2012
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    You specified an AC pulse- then need frequency desired. What are you feeding pulse into?
     
  4. crutschow

    Expert

    Mar 14, 2008
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    I believe he was using the term AC pulse in a somewhat redundant fashion. I think he just wants a square pulse with variable pulse amplitude and rep rate.
     
  5. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
    435
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    Yes I was.
    That sound about right there.

    Feeding it into a drum brain module, I would like to determine what voltage ranges trigger a soft hit, medium hit, and hard hit.
     
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    If the input imperiance Of drum brain module is high , a single turn pot, with calibrated dial could give pulse output of 0 V to supply V, using 555 timer IC. Single pulse or continuous roll.
     
  7. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    are there designs available for such a circuit? that sounds about what I need.
     
  8. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    Well I built a clock circuit from a LM555, the only thing it can't really do is adjust voltage, and tell me what voltage it's set to.
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    I think this is close to what you wanted: Supply V 9 to 12V regulated. With SW-2 down, pressing PB SW 1 will generate a single pulse. With SW 2 up, 555 will free run, generating a continuous roll. With SW 2 up & SW 3 open, output should stay high, allowing volt meter measurment of pulse amplitude, also allow output dial to be calibrated. For a pulse repitation rate of 1/sec,Pot R3 = 1M, C2 = 2μF. Pulse width, not specified,Pot R4= 10k. Pot R6 linear or log taper maybe 5k. With 12V R5 = 2k, 9V =1k If Brain loads output too much, will need to add a buffer amp.
     
  10. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    Actually I need to go from 0-9V, and I need to have control into the mV range. I'd ideally like to have control down to 10mV/step

    I've just been playing around with various things and experimenting in multisim and the attached design causes simulation errors either instantly or after a period of time (i think when voltage drops) depending on how I have the amp trim pot and/or the regulator trim pot set.

    I think the error is caused due to the voltage dropping below 0V, which may or may not be required by the brain. I'm not sure if it just detects a pulse of X volts, or if it requires the negative voltage produced by the piezo.

    I'm sure there are a few things wrong with this circuit but like I said I was just playing around after I "built" the 555 timer there.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    You haven't said that money is an object. One solution would be a LabJack or similar data acquisition device under control of a computer. Assuming you have a computer and modest programming ability, the device is roughly $120 and you'd be set to go wild. I think what you've described would be simple, and you'd have "infinite" control over the pulses, including precise voltage and timing control. The normal outputs are 0-5V I think, so you'd need to rig something to go higher, but the data acquisition functions of such a device would give you an accurate volt meter, so controlling a higher voltage circuit would be quick and easy. Since I already have one of these sweet things, this is definitely the approach I would take.
     
  12. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    money is an object. one of which I do not posses very much.

    Trying to do this as simply and cheaply as possible, as this device is merely just a single use testing device so to speak.
     
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