I bought my Arduino starter kit a few weeks back and have been getting the hang of the basics pretty quickly. I am looking to embark on my first real world project and am looking for some advice.
I want to build a TV lift for a 50 inch TV using a 12v linear actuator connected to a track within a hollowed out piece of furniture (probably a large chest or something wooden and rectangular shaped) that can be controlled by a remote control. I would prefer to power this using only 1 power source (either a 12v source that can plug into the wall or maybe a 12v battery) but I am worried about how to do this without damaging the Arduino. I have been reading up on relays and H-Bridges to convert power but it seems that most similar projects are using multiple power sources and they do not involve the use of remote controls. I recently purchased a bunch of ATTINY85's so I'm looking into the possibility of loading the code onto one of these so I would not have to keep my Arduino attached to the TV lift. I also recently purchased a simple 315Mhz RF M4 receiver and transmitter so I was hoping I could figure out a way to raise and lower the actuator a specific distance (because the exact distance will depend on the piece of furniture I end up using) with the use of state change detection code.
Any advice on the circuit design and code would be greatly appreciated!
I think you'll have better luck with a motor that winds/unwinds a cable to pull the TV up and let it down, or a geared motor to drive the track up & down. 50inch TV needs around 3 feet of travel, finding a linear actuator that long will be difficult.
Slider speed calculation: The following formula can be used to help select the correct speed of gearmotor.
6/[(number of seconds for full travel at max speed/60]
For example, if you wish to build a slider that will move 19” in 30 seconds:
6/[30/60] = 12RPM motor required
Moving mechanical stuff not really my strong area.
Have you already committed to a particular handset for the remote control? If not, I'd buy a standard wireless remote switch, and use that to toggle an output high and low. Use the output to power the drive motor forwards or reverse via a couple of limit switches so that when the output goes low it drives down to the bottom limit switch and stops, and when the output goes high it drives to the top limit switch and stops. No electronics or software required at all - just a standard off-the-shelf remote control, and some switches and wires. You still need to select the actuator and power supply etc, but that part only you can do.
CrossRoads: The reason I am looking into a linear actuator is because it seems like most professional TV lifts are made using them. For example check out this site:
I would consider looking into the motor route but to me that seems like there would be a lot more moving parts. Do you know of any examples I can look at that use a motor to lift something as heavy as a 50 inch TV? I am essentially trying to design a LAC board that is compatible/programmable with the Arduino and I'm trying to make the power connection as simple as possible. I figured I could attach the top of the linear actuator as high up as possible on the back of the TV to minimize travel distance - I am aware that I will have to buy a pretty big one. Any ideas come to mind after checking out that site?
Peter - I purchased the following remote and receivers:
As you can see these are not very expensive so I would be up for a change if these are not the best. Professional TV lift companies use infrared remotes so I may look into purchasing one of those. It would be really cool if I could control it using my current TV remote.
In my opinion, the slickest way is to find out the power on, power off code for the TV set. use that same signal to raise and lower the TV. you would probably need an IR receiver to get that signal and energize the lift and also turn the TV on.
regardless of the method of lift, gears, ropes, whatever, using a switch at the top would just remove power from the motor. then, the only way to apply power is to the reverse drive. ditto but in reverse for the bottom.
Ok so I finally purchased my 30" actuator and now I'm working on the circuit design but I'm stuck. The actuator is powered by a 12volt/ 4 amp battery (I bought separately) and I'm trying to build an h bridge circuit that actually works in both directions. I bought 4 TIP120 NPN transistors and I swear I have the h bridge hooked up correctly but I can only get it to work in one direction using 2 of the transistors (and I have to unhook the other 2 transistors from the circuit or else it doesn't work and they get very hot - maybe the other 2 transistors are somehow causing a short circuit??). It works fine with the 2 transistors (the base on both are hooked to arduino output pins and the collector/emitters are hooked up to 12v positive/common ground respectively) but I need to physically swap the positive and negative wires from the actuator in order for it to retract.....my goal is to be able to extend/retract the actuator by using some simple arduino code but I can't figure out the wiring, please help!
If you want to keep things somewhat simple, control the actuator with a DTDP relay like below The actuator probably already has internal limit switches, but you could add external ones. I think you can get simple IR remote/relay kits that could control the actuator, or make your own setup..
Yeah I was thinking about possibly just using a relay, I just liked the idea of an H bridge if I could get the wiring figured out.
Can you send me an example of the best DTDP relay to use with 12v at 4 amps? I see some online but they seem to be for either higher or lower current power sources. Do you think Radio Shack will sell one that would work for me?
Also, there are internal limit switches built in, can I just bypass the external limit switches in your drawing? I want to make sure there is no power being used when the tv lift is not moving. Also, I bought a cheap rf receiver and transmitter so I'm hoping I can eventually integrate that into my circuit to toggle the actuator.
