Interfacing different remote control systems...

[wedderwedder]

Hello,
Background on me - i work as an antenna designer - so have access to some SIMPLE electronics - and i mean simple....

Issue - a colleague has a work lagre TV screen set up with 'curtain' that opens up via remote control. press once to open (you cant hold the button down) press another button to close. Anyway. I would like this to open automatically when i turn on my amp. When i turn this on i do get a 12V OUT supply from teh amp. All i need is something that will effectively press 'open' on the remote when i switch on the 12v and then press 'Close' on teh remotw when the 12v is off. Now i have not got any real idea how to do this and i am not sure i have come to the right place to ask,. If this is a big difficult circuit and i am being cheeky asking for help then please tell me. Thanks in advance

 

[Resqueline]

No problem, you are being too humble if anything.
One solution could be to use a capacitor in series with the switched 12V, one resistor and two opto-couplers. 12V going up activates one coupler for some time and 12V going down activates the other coupler for the same time. Opto outputs are connected to respective button tracks on the curtain remote. Get the idea?
I can't guarantee it'll work just like that/ right away, & you might have to experiment a little with component values.

 

[wedderwedder]

Hi Resqueline
thancks for the reply.

Dont mean to be a pain but i forgot to mention that the remote for the electric curtains is RF does this make any difference?.

 

[Resqueline]

No problem. Neither is the RF bit as buttons are dc operated anyway. You'll have to solder into the remote nevertheless.

 

[wedderwedder]

I thought the remote type would not matter but just had to check. Being honest I have ZERO experience of opto-couplers and can't quite fathom out your very simple idea. Guess my electronics knowledge is worse than most... If you could walka complete novice through the layout I would be grateful but - if not I will try and find someone with more knowledge than me to help me with your plan. Thanks in advance and i look forward to full schematic and parts list - with cost prices by........ Er only kidding - I really appreciate your help.

 

[Resqueline]

I didn't have a CAD program installed so I just jotted a diagram on paper and scanned it.
The values of the parts are very non-critical, and you can use two single couplers instead of one double. There are many part numbers that'll work so you'll just have to choose a supplier first and then I can help you pick a part. You have a sense of humor, I like that.

 

[wedderwedder]

Thats GREAT - Thanks! ... The standard supplier i use at my work for antenna components is RS (rswww.com) i have the Resistirs / capacitors all here.. its just the opto-coupler item that i am unsure of purchasing... I have a MAPLIN near me. Oh and my sense of humour comes about when i am attempting something i know very little about... Seems i came to the right place for help. If you ever need an antenna for your boat.. Thats me

 

[(*steve*)]

Resqueline, can you explain the second 1K resistor? I could understand if it was connected to the left hand side of the capacitor, but not the way it's connected here.

Thanks

 

[Resqueline]

With a resistor across the LED's you'll get a quicker, more well defined shutoff of the couplers. Without it it becomes very gradual, long-winded, & more sensitive to the transfer-ratio/load of the transistors.
I guess you are thinking about having a load/pulldown on the 12V pulse input, and that is good thinking steve. If the pulse driver doesn't have a(n active) pulldown of some sort then the capacitor won't ever be disharged and the circuit will cease working after the first turn-on. A 1k resistor added from + to - there will warrant that this doesn't happen.

Maplin's couplers SFH618-2, RA57M, 4N25, and YY62S (dual) should all work in this application. The formers have a better transfer ratio than the latters (120/100/20/13%) but I don't think that'll matter here.

Antenna's are something I just felt like was being made at some factory and sold through some store, kind of a choose & use thing. I never thought I'd talk to a designer. Please tell a little more about what it's about if you like.
Oh, and I think you are just being too humble again (about the humour bit)..

 

[wedderwedder]

Well thanks for all your help - i have sourced the parts from RS (i hope).. Am going to try and make it this week. Will keep you informed.
As for antennas - SIMPLE really compared to this black magic. Normally cut a piece of metal to a half wave - which is 150000/freq in MHz - then stick some cable to the middle of it, hey presto a halfwave dipole. Stick a 1/4 wave bit on one end, attach the cable to that piece and you have an end fed J pole... Its easier than this electronics wizardry. As soon as my 'remote' works i will be back

 

[wedderwedder]

UPDATE!!
News not good... not all bad but not good.
Anyway - I made up the circuit first. before soldering to any part of the remote i thought i would use it to turn on a simple LED. I connected up an led accross a 12V supply to ensure it worked. i then used the 'Optocoupler' to turn it on. WHen i turned ON the voltage to the Opto circuit the LED did come on for approx 1 sec then tuned off.. SUCESS!! i then tried to use the Opto circuit to flash the LED when i switched power off.. This it would NOT do.. I left the power ON for a fair few seconds then turned it off.. it just would not cause ht LED to 'Flash on' Is this my dodgy circuit or... something else.....

Secondly - the Remote control is not what i (we) thought it was... On removing the top cover it appeare the buttons do not just connect Two halfs of a switch - the buttons are actually small buttons with 6 legs. That has thrown me TOTALLY... on testing accross the switch with a simple multimeter it appears that we have 10V across 4 of the outputs (relative to -ve battery terminal) until i press the switch - then this drops to almost 0V across each one. Nope i am stumped. Is this now getting into the realms of quantum electronics that need understanding of quarks etc??? do i need to first produce a robot to sort this mayhem out? Anyway - i thought i would update you on progress, some positive A LOT confusing.... I look forward to some guidance - or even a ''cant help some people'' response..

 

[Resqueline]

First problem; did you try to connect a 1k resistor across the 12V input as steve suggested & I condoned?

Second problem; huh, I'm stumped too, but if you can get a good closeup shot of the remote maybe I can get an idea..

If all else fails you might actually get to build a robot! One that physically pushes on the buttons..

 

[wedderwedder]

First problem; did you try to connect a 1k resistor across the 12V input as steve suggested & I condoned?

Second problem; huh, I'm stumped too, but if you can get a good closeup shot of the remote maybe I can get an idea..

If all else fails you might actually get to build a robot! One that physically pushes on the buttons..

Thanks for your time and patience,

I hope these are ok.

 

[Resqueline]

No probs with my patience, it knows no limits (well, almost)..

It's not easy to see where all the tracks go, but power seem common to all 3 switches. Maybe they are used to switch on power to the IC as well as signaling which button is pushed.
Do you think you would be able to draw up a rudimentary diagram of the essential wiring around (one of) the swithes? We can't just give up yet, the solution might not be as hard as it seems.

 

[Mitchekj]

(For the remote)

If you're getting 0V from gnd to the all the switch leads when pressed, it sounds like the switch is applying ground to something (or three somethings.)

From the picture, looks like some leads may not be connected to the plane, but could be connected to the primary side. (Upon further review, that looks like a healthy dose of old flux.) Hmm.

I'm afraid I have to agree, a drawing may be in order.

 

[wedderwedder]

Sorry but i dont think i would be able to do a drawing but i have taken a few more pics to try and help.

 

[wedderwedder]

pretty pore i know.
if you look at it with the battery at at the bottom of the pic then the 2 buttons on the left,the top one is OPEN and the lower one is CLOSE, as you will see there is another on the right which is a STOP button,dont know wether this helps or not.

 

[Resqueline]

You'll need to do the shots just half an inch further away and they'll turn out sharp.
And then there's the angle; looking at the pic's as they are, I'd like one slightly from the left and one slightly from the right.
I need to see how/where the tracks enter underneath the buttons.

 

[(*steve*)]

Secondly - the Remote control is not what i (we) thought it was... On removing the top cover it appeare the buttons do not just connect Two halfs of a switch - the buttons are actually small buttons with 6 legs.

The mechanical aspects are not a real concern. 6 legs may simply be to make the device more stable -- many smaller switches have 4 leads, even though 2 would be sufficient.

That has thrown me TOTALLY... on testing accross the switch with a simple multimeter it appears that we have 10V across 4 of the outputs (relative to -ve battery terminal) until i press the switch - then this drops to almost 0V across each one.

What you measure is what I would expect to see.

I've had a look at the image of the bottom of the PCB and it's clear that one leg of those switches is connected to the -ve rail, and from the other side of the board it appears that several legs may be common (or they're wired up in parallel).

The fact that they *all* go to 0v when the button is pressed would seem to confirm that.

What would be interesting is a resistance measurement from the pins that change state to the +ve battery terminal (with the buttons not pressed, and the battery removed) I suspect that all will be similar. (and between 1 k and 100k)

Then measure the resistance between these pins which change state and the -ve terminal of the battery (with the battery removed) while the button is pressed. I would expect to see a very low value (under an ohm).

If both of these suspicions are correct, then...

I also suspect that if you set your meter to a current range (say a 200mA range) and *carefully* touch one of the leads to the negative terminal (battery back in), and the other to a switch pin that is changing state, that the remote will act as if the button was pressed. I say be careful. because you are effectively shorting these locations together and if you touch the wrong place, bad things might happen -- the above tests should confirm that it's safe.

 

[(*steve*)]

UPDATE!!
News not good... not all bad but not good.
Anyway - I made up the circuit first. before soldering to any part of the remote i thought i would use it to turn on a simple LED. I connected up an led accross a 12V supply to ensure it worked.

Good idea Did you have a series resistor with the LED?

i then used the 'Optocoupler' to turn it on. WHen i turned ON the voltage to the Opto circuit the LED did come on for approx 1 sec then tuned off.. SUCESS!! i then tried to use the Opto circuit to flash the LED when i switched power off.. This it would NOT do.. I left the power ON for a fair few seconds then turned it off.. it just would not cause ht LED to 'Flash on' Is this my dodgy circuit or... something else.....

As Resqueline suggested, the other 1k resistor is almost certainly a good idea. Did one of the LEDs flash each time you turned the power on? Or just the first time? If you wired it up as Resqueline suggested, it should flash each time regardless of this second resistor. Without it, and if yo are simply connecting and disconnecting 12V, the "off" LED will not illuminate.

However I would also check that you have connected up the two optocoupler channels in opposite directions. It is possible that if you connect them the same way that only one LED will operate (due to small differences in ON voltage). It's also possible you have connected the outputs up the wrong way. Even though the inputs are forward and reverse, the outputs need to go the same way -- it sounds like at least one is connected the right way.

You could replace the optocoupler with 2 LEDs (connected in opposite directions and you will be able to see what the optocoupler would. If only one LED illuminates, or if one illuminates brighter than the other then that may point more directly to the issue.

If you are supposed to press the same button a second time (once for on, and again for off) then you could use an optocoupler that already has 2 LEDs in it making it essentially non-polarised. An example is the TLP120 (http://www.rockby.com.au/DSheets/31247.pdf )