Advice needed: adding continuity to simple launcher.

Discussion in 'Ground Support' started by BryRocket, Apr 10, 2019.

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  1. Apr 24, 2019 #31

    DaveW6DPS

    DaveW6DPS

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    The buzzer, resistor, and switch can be in any order. The breaker or other protection should always be first, as you have it

    I am assuming there are some more connections beyond those shown? Perhaps a "fire button to energize the relay?

    You do have a dropping resistor for the output LED, right?
     
    Last edited: Apr 24, 2019
  2. Apr 24, 2019 #32

    BryRocket

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    I don't think I do have anymore connections. The relay is wireless and has a remote to energize the relay.

    I don't have a resistor for the LED right now. Would I want to put one before the LED?
     
  3. Apr 24, 2019 #33

    DaveW6DPS

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    So the wireless is integral to the relay in this? My mistake. Normally this would be labelled as a "wireless relay board, or something similar.

    Unless it is an LED with an integral resistor for the voltage you are using, you need a resistor in series with it. If you bought a panel mount "12 volt" led that has the resistor you are fine. If it doesn't, you need to find out the maximum current for the LED in amps, divide the battery voltage by this current, and size the resistor as close as possible.

    For example: battery voltage is 12 volts and LED current needs to be 10 mA, then 12/.01=1200 ohms
    Note the 10 mA needs to be divided by 1000 to get amperes. The LED will actually drop between .3 and 1.8 volts making the drop across the resistor is less, which give you some margin.
     
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  4. Apr 27, 2019 #34

    Handeman

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    Actually that probably won't work. the + & - input on the relay probably means it's a solid state relay instead of a coil and contacts.

    If that is the case, it doesn't have contacts that can weld so the LED isn't needed.
    The big thing is, the + and ground on the output still work as a NO switch. It won't output anything from the + contact when you turn it on. You need to supply +12V to the + output and ground to the ground output with the circuit you want powered in one of those legs. The relay will allow current flow when the proper polarity input is supplied to the + & - inputs.

    Think of it just like a standard coil and contact type of relay, it just has certain polarities that must be observed.
     
  5. Apr 28, 2019 #35

    BryRocket

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    Thanks for the input and comments.

    I didn’t draw the relay exactly correct in that drawing. It has a (+) and (-) input and output. The (-) output is always a common and the (+) output gets switched and is NO. For instance, you can put an LED from the (+) in and (-) out and it works regardless of the relay state. Also, you can light an LED by connecting the (+) output and (-) input by switching the relay on. Does that make sense and help to explain how it works? I have decided to nix the switch after the LED just before the igniter hookups. I have wired this all up and it seems to work pretty good so far and I’m getting about 11mA going through the continuity circuit which is a pretty safe place to be I think. I’m going to work on it some more next week and I’ll report back.
     
  6. Apr 28, 2019 #36

    Handeman

    Handeman

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    I understand what you are saying, but it seems strange to be working that way.
     
  7. May 3, 2019 #37

    BryRocket

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    I have no doubt my drawing is hard to read but the device is working great and as expected (or as I wanted). I’m going to make a different case for the remote that has a key switch soon enough but happy with this. Continuity seems to work great with ematches and larger igniters. Putting out about 15mA through the LED+resistor. Will fire off 10 wrap 30g nichrome igniters no problem. Thanks to all of you for your input and help. I appreciate really appreciate it.

    IMG_2126.jpg IMG_2128.jpg IMG_2129.jpg IMG_2130.jpg IMG_2131.jpg IMG_2133.jpg IMG_2173.jpg
     

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