Thursday, March 11, 2010

TV Lift IR Receiver/Controller

Now that I have this awesome motorized TV lift in my bedroom, I wanted to enjoy it in as lazy a fashion as possible. So I needed to go about making an IR receiver/relay switch. The lift is controlled by a wired controller which consists of a pair of switches wired such that pressing one raises the TV and pressing the other lowers the TV.

I needed to replace these switches with Single Pole Dual Throw (SPDT) Relays that were rated for 24VDC and 3 amps (max current at 200 lb, but at 20 lb about 1 amp). I would also need to have an IR receiver that would control the two relays.

I started out with a Velleman MK161 2-Channel IR Remote Receiver Kit.
The downside of this kit is that the control chip that decodes the IR signal and controls the relays only works with Velleman remotes, and I wanted to use my cable remote (for all the DVR features). The includes relays were also only SPST, but they could easily be replaced.

I then came across a chip made by SIMEREC, the SIS-2, which is a 2 Output, Universal IR Remote Control Receiver switch.

My goal was to replace the Velleman chip with this one so it could be programmed to work with any remote control. Unfortunately, the pin outs on the SIS-2 were different from that on the Velleman, so it wasn't a simple swap. I remapped the pins using an IC PC Board from Radioshack and wired this into the MK161 board. I had to make a few other routing changes to the board as the Velleman chip needed a load to go into programming mode, whereas the SIS-2 needed to be grounded.

For the IR sensor, I went with a Vishay TSOP1140 from Mouser, since I was certain it would work with my cable remote. I used 6' of phone line to wire the sensor to the board, so I could put the control box under the dresser and have the sensor just in view on top of the cable box.

Lastly I decided to use 2 premade Relay Control PCBs from Sparkfun, instead of the mini relays in the MK161 kit. I had to mod the Relay Control PCBs to work with SPDT, but that only required some additional wiring.

I threw everything into a 5x2.5x2"project enclosure from Radio Shack and spliced the new control box into the wired controller cable. I decided to program the Picture-in-Picture channel up/down buttons as the up/down controls for the TV lift. I figured I would use PIP on a 26" TV anyway. After fixing a couple lousy solder joints, everything worked as planned. I can now turn on/off, raise/lower and watch TV without leaving the bed!

I might replace the hacked 4 board solution, with a single PCB that I design using CadSoft Eagle. I can get the board built for about $30 from BatchPCB.

Below is the schematic.


PCB design.


Materials:
  • PCB (BatchPCB #N/A; $30)
  • Programmable IR Receiver SIS-2 (SparkFun ##SEN-08753; $9.95)
  • DC Barrel Power Jack/Connector (SparkFun #PRT-00119; $1.25)
  • Mini Push Button Switch (SparkFun #COM-00097; $0.35)
  • Wall Adapter Power Supply - 12VDC 600mA (SparkFun #TOL-09442; $5.95)
  • IC Socket (Mouser #571-2-1571552-2; $0.80)
  • TSOP1140 IR Receiver (Mouser #782-TSOP1140; $1.11)
  • (2) SPDT Relays (5VDC 20A) (Mouser #655-T90S5D12-5; $2.49)
  • 4 Point Terminal Block (3.5mm) (Mouser #651-1990753; $1.77)
  • Voltage Regulator (UA78L05) (Mouser #UA78L05CLP; $0.52)
  • Diode (1N4007) (Mouser # 512-1N4007; $0.06)
  • (2) Diodes (1N4148) (Mouser #512-1N4148; $0.03)
  • Electrolytic Capacitor (100 uF) (Mouser # 647-UES1H101MHM ; $0.89)
  • Multilayer Ceramic Capacitor (100 uF) (Mouser # 594-A104K15X7RF5UAA; $0.08)
  • Multilayer Ceramic Capacitor (0.1 uF) (Mouser # 80-C330C104M5U; $0.30)
  • Electrolytic Capacitor (4.7 uF) (Mouser #647-UVZ1V4R7MDD1TD; $0.07)
  • (2) LEDs (Mouser # 859-LTL-307E; $0.10)
  • (2) Bipolar Transistors (2N2222A) (Mouser #610-2N2222A; $0.79)
  • Resistor (100 Ohm) (Mouser # 291-100-RC; $0.10)
  • (2) Resistors (220 Ohm) (Mouser #291-220-RC; $0.10)
  • (2) Resistors (4.7K Ohm) (Mouser # 294-4.7K-RC; $0.18)
  • Project Enclosure (5x2.5x2") (Radio Shack #270-1803; $3.69)
Total cost ~$65

Lastly just wanted to say thanks to the tech at Firgelli. He was extremely helpful in determining how to wire up the controller.

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