RS Recording Module - making it loop continuously

Discussion in 'The Projects Forum' started by bio88, Oct 16, 2013.

  1. bio88

    Thread Starter Member

    Feb 17, 2011
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    I've been tinkering with the Radio Shack Recording module to develop a repeating bird call. Something I learned from trial and error is you can remove the mic and land the wires on an output from a 1/8 mini plug and record direct from an MP3 player etc. You have to tweak the volume just right to reduce distortion.

    Anyway, to trigger the 20 second bird call loop I spliced in a small NO spring loaded push button. It takes a quick button push on/off to start the 20 second recording.

    Any ideas on how could I automate this button push every 20.5 seconds?
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    How about a good ole 555?
     
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    What chip does that module use? Many of them have a "repeat" pin, so if that pin is held HI/LO as needed the sound playback repeats indefinitely.
     
  4. Gadgeteer

    New Member

    Oct 9, 2014
    4
    1
    The circuit below accomplished the "looping feature" for the new Radio Shack module. It's not so much a missing pulse detector, rather the LED signal keeps the transistor shut off; when play ends the LED signal disappears, the capacitor is allowed to charge until the transistor switches on and the module re-triggers.

    I used a 1N5817 for the diode (it's important to use a Schottky, because of its lower junction voltage). I don't know what capacitor, I used a couple of surface mount from a dead computer board; it worked while experimenting with 20-33uF. Did not work with 2uF. Probably 10uF will work fine. The higher the capacitance the more delay between plays, but the more current will be demanded from the module's LED driver. Too little capacitance and it only plays a half second over and over.

    First remove the LED from the recording-module --- then connect the COB-side of the LED pad to #1 on the provided circuit. Connect #2 to the module's R3 (not the V+ side; if the "start" button is at the bottom as you work on the module, then connect to the LEFT side of R3, and to the left side of the LED pads). R3 is the pullup resistor for the "play" button.

    The "+" connection is to the circuit power, five volts (not the 9 volt battery). And ground is V-.

    The module will start immediately, play all the way through, pause (dependent on value of C), and restart --- playing continuously.

    (btw --- "COB", is CHIP-ON-BOARD. The black epoxy blob that covers the main integrated circuit...)
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    Cleaver solution. Let's hope the OP is still watching one year later.
     
  6. Gadgeteer

    New Member

    Oct 9, 2014
    4
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    Well, I found this site with a general net-search, so even if the OP doesn't see, odds are others will. I did a lot of searching and nobody seemed to have a working approach with the redesigned module. Several entries under the old "through-hole component" design, which does not work with the new item.

    This approach is easier than running a 555 --- betting someone will find this useful. I'm modifying a Disney alarm clock into a TALKING clock --- thanks to a YouTube entry! The RS device is acting like I have three separate audio clips that play in succession! :)

    We're approaching Halloween, this module will be great for electronic spookiness everywhere!
     
    RichardO likes this.
  7. Gadgeteer

    New Member

    Oct 9, 2014
    4
    1
    It occurs to me that an external LED (connected to the board's LED pads) could be fun. A superbright red will make a great flashing reindeer nose; yellow for ghost or spider eyes. You can probably get by paralleling two of the same color, current-hogging is not usually problematic for LED's unless different colors are paralleled. Get the brightest ones available. The "loop" circuit should still work with the LED present.

    Alternately, instead of connecting your transistor to the LED pad, omit the diode, change the resistor to 10K, and parallel your capacitor (smaller value, perhaps 0.1uF) with a cadmium sulfide photocell; should work fine as a "motion sensor". The fact that the module does NOT re-trigger if the "play" button is held down, works to advantage for this. Play begins when light DECREASES on the photocell. It should be easy for most here to reconfigure it to start on a light INCREASE if desired.

    Transistor type isn't important; a 2n2222 or 3904 should work fine; I used an old radio-control-car 8050 (hfe over 200).
     
  8. fredric58

    Member

    Nov 28, 2014
    143
    0
    I would also like to LOOP the recording, however I do not want to hack up the board. I found the 555 will not work because the discharge rate and charge rate are basically the same amount of time. Any ideas on how to close the play circuit for 1 sec, pause for 50 sec and repeat? Perhaps a 556??? or micro processor??? Thanks
     
  9. fredric58

    Member

    Nov 28, 2014
    143
    0
    Maybe it would be easiest to hack the board, where is the 5 v+ for the power circuit? and can I connect to the 9v grnd? I'm new at this. Thanks
     
  10. Gadgeteer

    New Member

    Oct 9, 2014
    4
    1
    Hi, Fred. Plus five volts is on R3 or R4, solder to the side AWAY FROM the black epoxy blob (next to the two 47uF black electrolytic capacitors, near the edge). Negative to the black 9V battery lead is fine. Cathode of the schotky diode goes to the LED, the side NEXT to the epoxy blob. And the transistor output (labeled #2 in the attached picture) goes to R3, the side NEXT to the epoxy blob.

    Yes you can use a 555, a single one should work fine; run it in astable mode (pin 2 to pin 6), set the "on" time (output low) to be < a second (resistor between pins 6-7), and as long as you want "off" time. You should be able to get the output (pin 3) to trigger the RS module -- I would use another schotky diode, cathode to 555 pin 3, anode to RS-module R3 "blob side". Alternately, you can INVERT the timing (so that the 555 output pin 3 goes HIGH for less than a second, and the discharge time via pin 7 is the long cycle) --- and connect most any NPN transistor (transistor base to 555 pin 3 through a 5000 ohm resistor); tie the transistor emitter to GROUND, and the collector to RS-module pin 3 "blob side". But be careful about how much current gets pulled from R7, by the timing resistor.

    Inverting the output can also be done with TWO transistors; a PNP connected to the 555 output (again 5000 ohm resistor, 10000 ohms if it works), PNP emitter to V+ and collector to the base of an NPN transistor through a 10000 ohm resistor. Again the NPN's emitter goes to ground, its collector to RS-R3.

    Clear as mud?

    :)
     
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