2 sec delay on reverse

Discussion in 'The Projects Forum' started by gerty, Jun 15, 2010.

  1. gerty

    Thread Starter AAC Fanatic!

    Aug 30, 2007
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    I'm trying to figure out a simple 2 second or so delay for energizing a relay.
    What I'm doing is starting a gear reduction (285 rpm) with a rf remote, the motor drives a pulley/cable for approx 10 seconds. When the cable reaches the right limit switch it stops, then reverses automatically.
    I was counting on the gear reduction to act somewhat as a brake, now I think I need to add a small delay after the motor stops before reversing.
    I don't want to get into adding a 555 or similliar circuit, but I may end up doing so.
    Any suggestions?
     
  2. Wendy

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    Mar 24, 2008
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    A simple resistor/capacitor may be all you need, depending on the relay coil. How much voltage, how much current?
     
  3. gerty

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  4. Wendy

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    The cap will be pretty large, but a simple RC charge will delay the relay. If you want slow on and fast off just add a diode. I think I have a illustration in my library, BRB.

    ********************************

    OK, I misremembered, it was the other way around. I need to draw an example of what I'm talking about. You can also use a transistor to decrease the capacitor size.

    Here is what I was remembering, the wrong schematic...

    [​IMG]

    BRB, drawing.
     
    Last edited: Jun 15, 2010
  5. Wendy

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    OK, looking at it I think the transistor is necessary, though I could be wrong. A 555 would use a few more parts, but I think this would work. It's weakness is it needs a discharge resistor, preferably before R1.

    [​IMG]
     
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  6. gerty

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    Aug 30, 2007
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    You da man!! Works perfectly. 2 seconds with these components
    Values:
    R1= 1.5k
    C1= 220uf
    Q1= pn2222
    CR1= 1n4001
    Relay I tested it on was 180Ω @12vdc
    Thanks
     
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  7. Wendy

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    Your welcome.
     
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