RC Launcher from a Doorbell

Discussion in 'The Projects Forum' started by MaxPower1974, Jun 19, 2007.

  1. MaxPower1974

    Thread Starter New Member

    Jun 19, 2007
    Hi All:

    Working at a summer day camp and would like to have the kids experience a "space" program by building a model rocket, going through different phases leading up to launch and recovery. I have designated some of the kids as "mission control" - who will be responsible for launching the rocket. However, I want to be the actual finger on the button to avoid any misfires.

    I bought myself a wireless doorbell, thinking I could hack that to allow for my launch trigger - however it seems replacing the speaker with the actual igniter just isn't producing enough current to light the ignitor. Any ideas how I may be able to do this easily?

    My first thought is to hook up a relay to the speaker wires, but all that may do is cause the relay coil to act as the speaker coil... I'm befuddled, since I have no electronics experience outside of college physics...

  2. beenthere

    Retired Moderator

    Apr 20, 2004
    The wireless receiver may not be able to heat the ignitor without modification. Nobody publishes schematics anymore, so finding a point in the receiver that can be used to control a transistor or FET to handle the ignitor current would need a meter, at the very least.

    An ordinaly dorbell pushbuton switch and two wires to carry the current is going to be the easist means of setting off the rocket. Just remove the battery before the launch so nobody can do the deed before the kids are at a safe distance.
  3. eckertd

    New Member

    Jun 19, 2007
    How about your wireless doorbell acting as a "remote safety" instead of a remote fire? Push to enable the ignition circuit. You won't need the current necessary to actually heat the ignitor.

    They can push the launch button as much as they want, but the circuit isn't enabled unless you're pushing your doorbell button.

    Safety first, of course, but they'll get the thrill from actually triggering the ignition.
  4. a_kent

    Active Member

    Jun 12, 2007
    If you have access to a voltmeter, try placing it across the speaker leads without the speaker there, and measure it in both DC and AC modes when you activate it.

    Is the speaker a true speaker, or a peizo element?

    Also look around the PC board and provide any numbers that you might see on chips, especially ones that look like they might connect to the speaker. A good closeup picture would really help here.

    I assume the part that would go in the house has a battery? It's not hooked up to the normal home doorbell circuit, is it?

    I love rockets!