DIY ILDA Buffer Advice

[Humphry]

Hi all.

Does anyone have any comments on the following for a simple voltage signal buffer for runs of 200m which is according to the datasheet 100ohms per km ... impedance I think it's called?

IDEA
Build a Dr. Lava style DAC, put that at the PC (or projector end?) and tune the gain/offset to get a nice 0v-5v for each channel on the projector end.


TUNING
I suppose I would need to have the projectors powered on for the drivers to 'use' the voltage and contribute toward the voltage drop (can't remember the term for this).
So would I have the projectors running, and then just measure the voltage vs ground at the projector end and tune accordingly?
But then how do buffers such as this sold semi-commercially (buffy/matilda) work without tuning, or do they and I have missed this?


CONSIDERATIONS
1) Are there any dangers ie blowing a driver by having 12v input into CNI/DHOM drivers (god knows how but in the event of say, a mistuning?)
2) Would the TL072 be sufficient for this application? Blanking fast enough, power sufficient, voltage differential sufficient.
3) Would this help at all with interference? I would imagine not..
4) Advantages of board being pc vs projector side?

Thanks and happy Halloween!

[badger1666]

Matilda is what you need
Stanwax on pl sells them
Check stanwax laser . Co.uk

[danielbriggs]

But then how do buffers such as this sold semi-commercially (buffy/matilda) work without tuning, or do they and I have missed this?

Dear Humphry,
I co-manufactured the MatILDA boards with Rob (Stanwax). The MatILDA boards are NOT designed to provide long runs of ILDA cables / signal boosting / amplification etc. they consist of 12x TL08x op-amps at unity (with a few extra things like voltage clamping, and ESD protection on all lines etc.).
The intended use is to provide multiple buffered (1:1) outputs at high impedance. This makes it possible to connect many different laser projectors together, all with different input impedances on the driver boards, sharing the same output signal with equal loading.

CONSIDERATIONS
1) Are there any dangers ie blowing a driver by having 12v input into CNI/DHOM drivers (god knows how but in the event of say, a mistuning?)
2) Would the TL072 be sufficient for this application? Blanking fast enough, power sufficient, voltage differential sufficient.
3) Would this help at all with interference? I would imagine not..
4) Advantages of board being pc vs projector side?

Thanks and happy Halloween!

1.) Quite possibly! I'm not sure all drivers out there clamp >5V on the signal lines; best to assume not!
2.) Yes. Although the TL08x's are suitable also (higher noise).
3.) I doubt it; is twisted pair + shielding still not sufficient?
4.) How would you make adjustments if your projector is mounted 20m up high on a truss?


Are you designing for a product, or looking for a solution to 200m cable runs, as there are other possibilities if the latter.

Best Regards,
Dan

[Humphry]

Are you designing for a product, or looking for a solution to 200m cable runs, as there are other possibilities if the latter.

Best Regards,
Dan

Hey and thanks for the reply! I see, so your products are not in fact what I am looking for.

I am not designing a product - simply looking for something to help with long analog runs with no losses. I have tried a USB extender - very unreliable and the VNC route just doesn't really cut it.

What would you recommend? Do you think I am being pedantic over the voltage drop and I should just go ahead with the cable and see what voltage I get? There will be a resistance of approx 20 ohms for the entire run on each core according to the datasheet.

Much appreciated!