RIYA DAC and testing RGB output

[paulckruger]

If this is the case, you need a pulldown transistor or open collector TTL inverter chip between the RIYA and your Projector to bring the projector into compliance with the standard. Odds are the RIYA is just fine.

I wonder if anyone here has a pull down circuit already designed to share? Easier than re-inventing the wheel.

[mixedgas]

See inline attachment
This is the new version with speedup cap and 100 Ohm emitter resistor.
Do not omit the Zener. Drawn in "WalleyeVision 2"(tm)





Steve

[paulckruger]

Thanks much. One for each color I assume.

[paulckruger]

Thanks much. One for each color I assume.

Put three on a small board in series DB25 --> DB25 with all other pins feed thru untouched? Plug in between DAC and showcard connector...Correct?

Will see if +5 is available one of those DB25 pins or add external power in from USB or via +5 volt regulator IC which I have around.

[paulckruger]

I am doing my home work. Damn, thought I left that behind me to be dumb after leaving school !!

Have the DB25 pinouts and ILDA spec sheets.

Here is what I know to be followed by my thoughts as related to my projector.

1. Pinouts for RGB are analog 0-5+
2. My show card appears to be only TTL output. (on/off only)

Thoughts.

If I were to modify the connections from ILDA input such that the X/Y signals went to the show card, as expected but send the RGB inputs directly to the laser module so they are not connected to the show card at all.

The voltage range is correct for analog and this should eliminate the TTL issue and give me unlimited color control.

That would let the show card manipulate the galvo's but let the ILDA output directly manipulate the lasers, hopefully bypassing the issue of inverted output on the Chinese show card.


I am thinking I need use only X/Y, ground and perhaps interlock connections to the show card for galvo operations and ground and RGB+ to the laser's driver analog input jacks. ( interlock sort of irrelevant if the laser modules cannot be blanked by the showcard but perhaps the card will sit idle...don't know )

Sound reasonable?

[swamidog]

you know...

if you really wanted to just do things right(tm), you could throw out the sketchy TTL laser drivers in your projector and replace them with good analog drivers.

your projector would be *much* better and you wouldn't have to mess with a TTL inverter widget.

two of these would solve your problem: http://lasershowparts.com/store/inde...&productId=304

I am doing my home work. Damn, thought I left that behind me to be dumb after leaving school !!

Have the DB25 pinouts and ILDA spec sheets.

Here is what I know to be followed by my thoughts as related to my projector.

1. Pinouts for RGB are analog 0-5+
2. My show card appears to be only TTL output. (on/off only)

Thoughts.

If I were to modify the connections from ILDA input such that the X/Y signals went to the show card, as expected but send the RGB inputs directly to the laser module so they are not connected to the show card at all.

The voltage range is correct for analog and this should eliminate the TTL issue and give me unlimited color control.

That would let the show card manipulate the galvo's but let the ILDA output directly manipulate the lasers, hopefully bypassing the issue of inverted output on the Chinese show card.


I am thinking I need use only X/Y, ground and perhaps interlock connections to the show card for galvo operations and ground and RGB+ to the laser's driver analog input jacks. ( interlock sort of irrelevant if the laser modules cannot be blanked by the showcard but perhaps the card will sit idle...don't know )

Sound reasonable?

[paulckruger]

I think you misunderstood my last post. The laser drivers ARE analog already. The TTL issue resides with the showcard, not the drivers.

It is the output of the show card that is TTL.

DAC (analog out) ---> Show Card ---> TTL out ---> Laser Drivers

My idea:

DAC: ( X-Y ) --> Show Card -->galvos
" ------\ --> RGB analog ---> Laser Driver

[swamidog]

if that's the case, just bypass the showcard and tie the ilda signal directly to the laser drivers.

what is the show card?

I think you misunderstood my last post. The laser drivers ARE analog already. The TTL issue resides with the showcard, not the drivers.

It is the output of the show card that is TTL.

DAC (analog out) ---> Show Card ---> TTL out ---> Laser Drivers

My idea:

DAC: ( X-Y ) --> Show Card -->galvos
" ------\ --> RGB analog ---> Laser Driver

[paulckruger]

if that's the case, just bypass the showcard and tie the ilda signal directly to the laser drivers.

what is the show card?

Exactly what I said. LOL

Showcard = It is a cheap Chinese version. I have no idea who really made it. Came bundled with the galvos and power supply.

[paulckruger]

Solved. No circuits needed.

I tried my idea as outlined above and it works great. I now have full analog control of lasers.

WHAT I DID:

I soldered four wires to the DB25 connector, Gnd, R+, G+ B+ and routed past the show card controller directly to the analog input pins on the laser drivers. RIYA test program lets me adjust colors manually...fully rainbow now !

Next part of this is to research bypassing the showcard for purposes of driving galvos. I need to do some measurements to determine the pin outs and voltages of the show card --> driver boards. If I can do that I can put the board in a drawer somewhere.

That will be for another thread since this one was specific to driving the lasers. Thanks for the help guys.