I have a DFPlayer Mini with an SD card with one song on it. I want to make a circuit to power it on, and after a couple seconds, simulate a button press through a 33k resistor on pin 12 to trigger the play/pause command. I couldn't find anything online on whether or not NPN transistors can have the collector hooked to ground (in order to use it as a relay of sorts). If that's not the case, what would you guys do?

circuit diagram In this image, I have two 555-timer monostable circuits; the one at the top will turn its output on after ~2.4 seconds, and the one at the bottom will turn its output on around 0.25 seconds after that. The transistor hooked up to it acts as a NOT gate (current flows only while the first 555's output is on and the second's is off), so that the output of the circuit is: nothing for ~2.4s, on for 0.25s, then off again indefinitely.

Is it possible to use another transistor to "close" the circuit between the DFPlayer Mini's pin 12 and ground with a resistor in between, or do I need a relay / something else? I'd like to keep this as thin as possible.

I'm a beginner so I apologize for any mistakes I probably made.

  • \$\begingroup\$ Have you found a solution? \$\endgroup\$
    – zhekaus
    Commented Sep 27, 2023 at 23:37
  • 1
    \$\begingroup\$ @zhekaus yeah, it turns out you can just short pin 12 to ground and it'll play, even if you don't "un-short" it :) \$\endgroup\$
    – Marvil
    Commented Oct 17, 2023 at 20:28

1 Answer 1


This could work as long as the collector can be a bit above ground and still work.

You could also use an N-MOSFET in place of the BJT and get closer to true ground.


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