302Views3Replies

Author Options:

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

user
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."

Select as Best AnswerUndo Best Answer

user
rickharris (author)2011-09-16

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

Select as Best AnswerUndo Best Answer

user
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!

Select as Best AnswerUndo Best Answer