TV Drop Down Lift

Discussion in 'The Projects Forum' started by Rumorco, Jan 24, 2016.

  1. Rumorco

    Thread Starter New Member

    Jan 24, 2016
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    0
    I have a quick project idea, thought I would run it by all you genius minds and see if it's possible.

    I can build a tv drop down lift (goes up and down vertically with heavy duty cabinet rails), I can set up the pulleys, and the spool where the wire would roll up and roll down (wire would be attached to the back of the tv and run through a series of pulleys and to a motor with a spool where wire would wrap on and off, which in turn lifting and dropping the tv). My question is, I'm not the best with making circuits etc, what kind of motor do I use and how do I make it start spooling up the wire and stop at the right time. Then if I push the button again, it slowly spins the spool backwards and lowers the tv? Is this possible? I really want to build this lift, don't want to buy one. Mechanically I can make everything work good but electrically... I need some help! Or maybe there's some sort of kit I can buy? Maybe install some push button limits into the cabinet rail sliders? I can put two buttons in each rail to make sure safety (one limiting maximum lift height and one bottom limiting lowest the tv should drop).
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    1,438
    368
    Have you considered using a linear actuator? They have internal limit switches, AFAIK you just need to apply power to extend and simply reverse the polarity to retract, a DPDT switch is all that's required for controlling it.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,991
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    A simple spool is a bad idea unless you use a worm gear that would allow you to stop the motor and have the Tv stay where it is. That is, you don't want to keep a constant current on a motor that is simply holding the tv to a single point.

    Everything else you want to do it easy. There are several design options. An encoded motor or stepper motor that allows you to monitor how many rotations have occurred and lets you stop the motor after a specific number of rotations.

    Or, you can use a current sensing resistor and stop the motor once it strains itself I to a stop-block.

    Or, you can use limit switches and have it stop itself that way.

    Microcontrolers (like Arduino ) removes many chips from the project but you will have to learn how to program it.
     
  4. Rumorco

    Thread Starter New Member

    Jan 24, 2016
    2
    0
    An actuator is genius!! Why didn't I think of that earlier?

    Thank you guys!
     
  5. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    Here's an inexpensive, 2-channel remote control assembled relay kit I used to replace a failed unit in a motor driven TV lift unit I had, and the kit works very well as a replacement.
    The receiver has two separately controlled SPDT relays that I connected in a bridge configuration to drive the (DC) motor and reverse its current for up and down (#1 remote button for up and #2 for down).
    It also has two limit switch inputs that can be used stop the lift at the top and bottom (I used two micro-switches for that purpose).
    [Note that you need to add reverse connected diodes across each relay bridge contact so that the inductive current kick from the motor has a path when the motor is stopped, to avoid welding the relay contacts.]

    My lift uses a DC worm-gear motor driving a threaded vertical jack-shaft to raise and lower the lift. The worm-gear prevents the weight of the TV from back-driving the shaft.
    It's geared so that it takes about 15 seconds to raise or lower the TV.
    The system has the jack-shaft nut connected to cables which uses pulleys to multiply the movement so that the TV moves twice the distance of the jack-shaft nut.
    That is so the jack-shaft isn't visible when the TV is lowered
     
    Last edited: Jan 25, 2016
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