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Im looking for a simple circuit that shorts an mp3 players play button briefly Answered

for a Halloween project, barking dog head
need a circuit that when powers on "presses play" (will solder wires onto play button switch
just needs to be a short pulse to get the unit to play
the circuit will need to be triggered by a 6v dc motor starting...and can use the same power as the motor to power itself...
pretty straightforward 
motor comes on - powers circuit - circuit shorts play button for a quick pulse - mp3 player plays sound clip - people jump and scream
thanks in advance

3 Replies

rickharris (author)2011-09-16

You could introduce a 555 timer set up as a monostable (one shot) to trigger a relay. That way the player only gets a single trigger per cycle you can adjust the 555 to achieve the required time.
from Wiki

"In the monostable mode, the 555 timer acts as a “one-shot” pulse generator. The pulse begins when the 555 timer receives a signal at the trigger input that falls below a third of the voltage supply. The width of the output pulse is determined by the time constant of an RC network, which consists of a capacitor (C) and a resistor (R). The output pulse ends when the voltage on the capacitor equals 2/3 of the supply voltage. The output pulse width can be lengthened or shortened to the need of the specific application by adjusting the values of R and C.[5]

The output pulse width of time t, which is the time it takes to charge C to 2/3 of the supply voltage, is given by

t = RC\ln(3) \approx 1.1 RC

where t is in seconds, R is in ohms and C is in farads. See RC circuit for an explanation of this effect."

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rickharris (author)2011-09-16

Wire a micro switch across the button and put a cam on the motor to operate it.

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Pyro667 (author)rickharris2011-09-16

hmm...i think that may not work...not because its a flawed design...just the motor will cycle more than once which will cause the mp3 player to pause
i had wired it with a relay....but the relay stayed on the whole time the motor went causing the mp3 player to not play until the motor stopped

Thanks for your quick reply!

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