Celexon Electric Tab Tensioned Screen Automation

PeteThePlanner

Novice Member
Hi there,
I have just purchased a Celexon Electric Tab Tensioned Screen. It has a control box wired to it which contains the IR receiver for the remote control. Ideally I want to set the screen up so that when the projector is switched on, the 12v trigger can instruct the screen to open and conversely, when the projector switches off, the screen retracts. The control box has no facility as I can see to connect the projector's 12v trigger to it. Inside this control box there is an RJ12 port with pins marked as follows:

pin 1 +5v
Pin 2 IR
Pin 3 Up
Pin 4 Stop
Pin 5 down
Pin 6 GND.
When I test the pins with my multimeter. Pins 3,4,5 all have 7.3v on them. I have manual push buttons on the side of the receiver box for up, stop and down. When I test these connections, one side of each switch is connected to ground. The other sides of the switch do not have any voltage on them. I was hoping they would have the same voltage as pins 3,4,5 of the RJ12 on the basis the RJ12 socket would simply be replicating the connections across these 3 switches. When I test these there is no continuity between the push buttons and the RJ12 pins so looks like they are completely independent circuits.

Would it be as simple for me to make connections between, say, pins 5&6 to activate the screen to come down and then pins 3&6 to make it go back up? I am worried that as pins 3,4,5 have voltage on them by connecting one of them to the GND pin would actually cause a short circuit rather than activate the screen operation.

I was hoping I could design and build a simple relay controlled circuit with a timer that is operated via the projector 12v trigger which in turn would connect to the screen's RJ12 port to instruct the controller to open the screen and then do the reverse when the projector switches off. Would anyone have any knowledge of this controller box and how I could perhaps achieve this? If not, I will use the screen with the remote I have.
 

Attachments

  • Celexon Remote Controller Receiver Box.jpg
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Holly80

Active Member
How good are you with electronics, do you already control your pj with alexa? Or an app or home automation server?

you could use an esp8266 with your own firmware or tasmota and control those pins using WiFi.
 

Holly80

Active Member
My take and it would be an experiment would be to use a resistor to ground those pins with a large resistance at least 10k to start that way any current would be limited but i am an amateur diy hobby electronics person proceed at your own risk. Other option would be to attach switch wires to the onboard push buttons and use some transistors to control them. While you may not find that board electronics schematics you may find similar ones elsewhere. Other option is to take it out and trace the tracks and components
 
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PeteThePlanner

Novice Member
How good are you with electronics, do you already control your pj with alexa? Or an app or home automation server?

you could use an esp8266 with your own firmware or tasmota and control those pins using WiFi.
I have basic skills but no knowledge of building my own home automation devices. Having just looked up esp8266 and Tasmota I think they are beyond my skills to use. I was hoping s simpler solution could be found by hard wiring the projector 12v trigger to a timer controlled relay so, for example when the projector is switched on, the 12v trigger operates a relay to connect the "down" circuit of the screen. The timer is set for, say, 1 second which mimics the actual time the button would be physically pushed so the relay is de-activated rather than it staying energised until the projector is turned off. Then a similar circuit to do the opposite when the projector is turned off.

The key to any solution is to understand how to connect the pins on the RJ 12 socket. Is it simply a case of connecting the "down' pin to "GND" pin to make the screen go down. I know I can try this by connecting the 2 pins but I am concerned that it could cause a short circuit and blow something.

Another way I can connect to the screens controller box is to solder onto the existing up, down, stop push buttons and use my relay idea to close the circuit that the buttons operate. This wouldn't be as nice as a circuit that can just plug into the RJ12 port but would do the job.
 

Holly80

Active Member
When you measure the voltage on the switches how many pins are there, some micro switches have four pins which are actually 2 for each side of the switch eg 2 are connected together.

It looks like the +5v could be to power a ir receiver perhaps. Have you tried to find any thing which is sold to plug in to this port? Might be worth looking at these for options there might be an off shelf solution.

the esp8266 once flashed with tasmota can allow to control relays etc. You can buy these as hobby boards with built in usb for flashing. Electronically it should be no more challenging then what your proposing, how would you power your relays? I would be more concerned concerned with attaching anything to the pj?
I knew nothing a few years ago now I fix things rather then throw it out, these are skills worth learning if you have time
 

PeteThePlanner

Novice Member
Thanks for your message and assistance. I contacted UK office of celexon and they do have an off the shelf unit costing £169 which I think is a unit designed to operate the screen from the 12v trigger. But, really, £169 for it? They said they don't have knowledge of the RJ12 port but have asked for any information if I can figure out how to interface to the RJ12.

In answer to your question about power to the pins, the 3 pins for up, down and stop all have 7.3v. if I connect one of these to the GND pin I am hopeful this would trigger some logic in the control box - perhaps the logic is in the ground side of the RJ12 port. The concern I have is experimenting and connecting across these pins to see what happens only to find it blows my controller box.
 

PeteThePlanner

Novice Member
Thanks for your message and assistance. I contacted UK office of celexon and they do have an off the shelf unit costing £169 which I think is a unit designed to operate the screen from the 12v trigger. But, really, £169 for it? They said they don't have knowledge of the RJ12 port but have asked for any information if I can figure out how to interface to the RJ12.

In answer to your question about power to the pins, the 3 pins for up, down and stop all have 7.3v. if I connect one of these to the GND pin I am hopeful this would trigger some logic in the control box - perhaps the logic is in the ground side of the RJ12 port. The concern I have is experimenting and connecting across these pins to see what happens only to find it blows my controller box.
I suppose another possibility is to build an IR transmitter that has the 2 IR commands for up & down. This circuit could be triggered by the projector 12v trigger to transmit the down command and then when the projector switches off and then transmit the up command. I haven't looked into this as a possibility yet
 

Holly80

Active Member
I have used a raspberry pi zero with ir diode and ir receiver using lirc this is interfaces with OpenHAB running on my server. I have a web gui and have connected it to Alexa. Saying movie time drops screen drops lights and fires projector. PJ and screen are controlled by inferred using Linux Infered remote control but I have used an old version of the raspberry pi os from dec 2018 which works. Total cost £30 quid
 

Holly80

Active Member
I wish I had your skills and knowledge. The older I get the harder I am finding it is to learn new skills.

I am new to this only being playing around with electronics for a few years and I started this late in my life. Something like this is a good place to start to learn. You have an objective and an idea how to proceed.
 

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