Hi Everyone,
I've just purchased a 15.4" WUXGA and MST for my first projector build. I'm just wondering if anyone has tried what is outlined on this website with the mst controller.

http://www.engadget.com/2006/12/06/how-to-...ojector-part-6/

They've used a relay and tapped into a spot in the LCD circuit board so that when you turn on the lcd, it fires up the lamp. They also made sure to tap into a spot so that if the lcd goes into standby, it doesn't kill the lamp. I'm just wondering if anyone has tried this, and where they tapped into the mst controller. This would make it perfectly possible to turn everything off and on using just the remote. That is, if the fans are set up on temperature switches.

Any ideas where to tap into a spot that stays between 3 and 12 volts DC whilst the lcd is on or in standby, and at millivolts when turned off?

Bevan

So, i take it no one has given this a try? Maybe ill have to be the first. Hope there'll be something with the required voltages around the edge of the board on the connectors.... Would make things a hell of a lot easier. Would be rather worried about touching the board with a soldering iorn. Should work fine though. The solid state relay will draw hardly any trigger current.

Do the mst controllers have a built in amplifier like the board in the above website?

Bev

I can't offer any helpful advice, but I'm very curious to see how this turns out. Hopefully you don't fry the controller, those aren't cheap

Ive done this on my element tv. You can use a transistor to switch your fans on and off too.

I think ill go with a thermal switch to turn my fans on and off, so they run at anything over 30 degrees celcius. The thermal switches I know I can get my hands on are 30 degrees, 50, 70 and 100.

I also plan on using a latching relay and another thermal switch as an overheat detection. This would mean the lamp would shutdown untill a momentary reset button is pushed. What value thermal switch would you recomend for this sort of application? Id probably put it as close to the lcd as possible, as this is where the temperature matters.

Thanks for all the input so far. I'll scan and post my tacky hand drawn circuit diagram when I get home.

Thanks again,
Bevan

I would use a 50 and put it next to your ballast. Im using a thermal switch and a transistor. This turns the fan on with the projector and runs it until it cools off.

You can reset the latching relay without a switch by using a capacitor and resistor. To reset the relay you only need to switch the power off and on.
Here’s the schematic for my control circuit:
Click to view attachment

The top relay receives a signal from the LCD control board via the transistor and supplies power to the rest of the circuit.
The latching relay is the one on the bottom. If it receives a signal from the fan controller (over temp or low fan RPM) via a transistor it will cut the Gnd connection to the power relay (turns off the lamp). To set the relay, power needs to be removed and reconnected. This is achieved using the220uf capacitor and 100k resister connected to the set coil. The 220uf capacitor is large enough to supply the coil with a brief pulse of power at start up then have no DC connection leaving the reset coil free to operate on a fault.


Hope some of this is helpful
DJ

EDIT:
The diode connected to the transistor’s collector and the 10uf capacitor could be removed if you have a DC signal. I had to include them as the fan controller I use supplies an audible tone so the diode simply rectifies the signal and the capacitor smoothes it.

You could use a thermostat from an old electric frying pan or and electric cloths iron. They are more sensitive to changes (most of them) and are adjustable.

DJ

I thought it seemed alot easier than using a fairly simple circuit and having to etch a PCB. Then again, that circuit of yours is relatively simple. Did you have to etch a board? Or did you end up just soldering it all carefully together so nothing shorted?

I was also thinking of running a 12v lamp off the relay side of the overheat thermostat so it would light when the overheat circuit tripped.

I etched it.
Click to view attachment
Click to view attachment
I usually use plotter to draw directly onto the PCBs using solvent ink. I haven’t used it for a while so the pen is full of dried gunk and needs a good clean. So I just hand drew it. Only took about an hour from start to finish.

Stupid drivers.... trying to get some photos up but having cammera issues

Well, a bit of an update. Today I went shopping and bought enough 9mm MDF to sink a ship. 4 hours after I got home I have a pretty descent looking box, but without a finished focusing mechanism. I think I'm going to just go with a sliding tray sorta focusing mechanism. Should work fine. It's not going to get moved around much anyway.

I also payed a visit to Jaycar electronics (www.jaycar.co.nz) and got some bitz n' bobz to help wire this thing up. I've got plenty of wire lying around, but just needed switches and relays. The SSR that I bought has a 240v output side rated at 40A, and the trigger side triggers between 3V and 32V DC. What current should I expect the trigger side of this relay to allow to flow with no other resistance at say 12 volts? I hope it's not enough to fry anything on my board! :S I'll take it to work tomorrow anyway and run some tests on the relay with some nice test gear.

I'll post some pictures of my half finished box. It's huge :S. lol. It needs a good sand and a coat of paint when I get it finished. What is this high temperature paint that I hear everyone talking about, and where can you get it?

Another thing that's on my mind is a reflector. Currently I haven't ordered one. I got a condenser with a 220mm focal length with my set of fresnels that have focal lenghts of 220mm and 650mm. I also got a Pro lens. Do I really need a reflector? Is there anything that I could use instead? I'm getting really sick of getting shafted by huge international shipping rates.

Bevan

EDIT: might take me a while to get the photos up.... just downloading the drivers for my mums DSLR that I borrowed.

Ok, here come the pictures...

Here are some more

Here's the electronic bits. Got a 12v transformer rated at 2 amps, the relay I mentioned before, 2 thermal switches (normally open), a momentary push button switch with a built in lamp (will be my overheat reset switch and lamp), and also a socket for a regular pc power cord with a built in switch and fuse holder. Oh yeah, and a latching relay for my overheat circuit that will shut off my lamp permanently until the reset button is pushed.

The powersupply may seem a tad overkill, but I'm sure i'll use it to it's full potential at some stage.

I took a look in the Jaycar catalog and found a 40A SSR ( SY4084). Although it doesn’t list the control current, its brother (SY-4086) has a current of 28mA. It will depend on where you connect it on the LCD controller, whether or not it will drive the relay. It might be safer to add a transistor in-between.

A reflector is good value.

Thanks for the suggestion. How would you recommend wiring up the transistor? I'm not the best with working out that sorta thing.

Thanks a bunch,
Bevan

Yeah, I'm just having a look in the catalog too. It's Direct Current brother relay specifies a max control durrent of 28mA as you said. I guess this must be at the max control volgate of 32vDC.... At 12V it should be pretty tiny.

Come to think about it, since the relay trips at as low as 3volts, and I"m planning on running my cooling fans off the same power supply, this could work rather well.... The power supply has adjustable voltage. I could tweak my fan speed, as long as that latching relay still trips.

Woohoo! My 15.4 and MST arrived in the mail today. Another query. From what I have seen, it appears that the backlight control on this controller is always on, no matter whether you flip between channels or so on. It also doesn't appear to automatically go into standby and shut down the backlight. It would appear that you have to actually use the remote to shut everything down. Some other lcds blip the backlight when you change between sources. Can anyone confirm that the backlight on this monitor/controller will always remain on, reguardless of having no source and being left sitting for ages? If so, I can just tap into the backlight 12v wires before they go into the inverter as far as I can see. They're made to carry descent current, so there's little chance of frying anything! Any reason anyone can see not to try this.

Today at work, I found that if supplied with 12v and I put a 1.2k resistor in series with the SSR, I found the current to only be 7.2mA and the voltage across the SSR to be 3.3V. Anything less than about 3.3V and the SSR wouldn't trip.

Bevan

EDIT: RATS... it does go into standby. Scratch that plan. Now if only I could find my good multimeter. I don't dare trust touching this thing with a el cheepo meter.