Creating Component Video inside the Amiga

[rkauer]

Originally Posted by Stedy

Rogerio,

The schematic has one error, on the B-Y connection. You have shown the Cr (R-Y) output and stated 'Repeat for Cb (B-Y)' this is incorrect, the B-Y level would be wrong.

From the Blue Video input, you need to fit a 51K resistor in parallel with a 5.1K resistor to get the right luminance (Y) level otherwise you will have Y= 0.3R + 0.59G + 0.11B, with your circuit you will have Y=0.3R + 0.59G + 0.3B, or in simple terms, a video image with too much blue!

Oops! My bad! I forgot about the different resistor net in the blue circuit. Thanks a lot, Ian!

If I may also make a few suggestions to improve the design.

Add decoupling capacitors on the -5V supply to each op-amp, the AD818 datasheet recommends 0.1uF and 2.2uF per power pin, in my opinion, forget the 2.2uF but fit the 100nF, the 330uF capacitance you have on the converters should suffice.

Also add a 100nF capacitor by the input of the 7805, it never hurts.

I hope the circuit works OK.

Ian

Will made the mods in 1.1 revised schematics. Those extra caps are needed, indeed. I'll put a 47uF plus a 100nF before the L05, too. Better safe than sorry.

Sourcing update: not a single shop have the MAX764, here! Damn! I'll need to source the components by Maplins or other good international vendor.

Delays, delays...

[Zetr0]

@RKauer

my friend, they have them on www.futurlec.com infact click here for direct link

I have used futurlec plenty of times, usually take about 2 weeks, (3 over holiday periods) I have never had to pay any custom fees or any added VAT either.

hope that helps

[rkauer]

Originally Posted by Zetr0

@RKauer

my friend, they have them on www.futurlec.com infact click here for direct link

I have used futurlec plenty of times, usually take about 2 weeks, (3 over holiday periods) I have never had to pay any custom fees or any added VAT either.

hope that helps

Zetro (and Ian, too), thanks a lot AGAIN, my friends. Zetro spare me a lot of time (and patience).

Just another redesign(!): dropped the AD818 (5.20USD) (1 costs more than the dual original MAX4451, even the AD818 is a through-hole piece!). What a robbery! So, back to the infamous MAX4451 (4.20USD).

Grand total, so far (only for chips, schottky diode and inductor): 21USD (ship included).

More 20BRL for the dual-layer board (no metallized vias) = 11.79USD.

So my main goal: less than 40USD to mount the unit is dangerously near. Put also that lot of high-precision resistors (0.20USD each 10, if Futurlec has those "weird" values in metal-film) and up to 12 small caps and we set over than this expected amount...

My "dream chip" is the National Semiconductors LMH7762 (any one of them, TSSOP or SOIC). 400MHz, 1800V/us, faaaast settling time, quad op-amp in a single package. But nobody have it to sell!

Sigh! Back to the express-PCB...

[rkauer]

Well, I found the MFH6722 (both parts: TSOP and SOIC) in Digikey Corp. Only USD5.23. But USD11 for S&H!

And I'm unsure if this is an affordable company like Futurlec. Maybe someone can point me in the right path.

[Zetr0]

I find DigiKey VERY expensive for the items... alas at times there the only ones that seem to stock a product.

[rkauer]

Originally Posted by Zetr0

I find DigiKey VERY expensive for the items... alas at times there the only ones that seem to stock a product.

And so do I. It's a shame that no other internet company have this little beast in the list. Digikey have @least 94 units in stock.

If I could buy a large order (where large means >USD25.00), the handling will drop 5. BTW: I made a mistake: 11 is for handling only! Shipment is another issue! They only do UPS and similar (in a "to bill the costumer" basis).

Yep, not a nice seller.

[edit]: Found the chip @ Farnell! 3.02 Pounds plus shipment! Yay! Zetro, if you buy regularly from them, can I ask you to buy one for me?

[chiark]

Did this ever get anywhere? Sorry to bump a thread from the dead, but composite out on the Amiga would be very, very cool

[meega]

I think you mean component video, which is what this thread is about.

[chiark]

Blimey, yes, you're absolutely right. Component. It's exactly what I'm after. I run out of attention after 5 chara...

[rkauer]

Yep, the design is done. Not produced yet by lack of components (those op-amps are hard to grab in Brazil).

But the design have no flaws, that's for sure.

[chiark]

What are you needing? As mentioned previously, I'm five miles away from Farnell...

[rkauer]

Everything?

[AlfaRomeo]

rkauer why do you don´t post the scheme?.. so who want to could make and test it

[rkauer]

The schematic is in the first page of this very same thread.

[chiark]

I thought you'd made revisions based on Stedy's comments and your own comments above, and rolled it into a 1.1 design?

If you post an updated schematic, I'll get the parts and post them to you. I'll also have a go at building it on a breadboard...

Any ideas on obtaining a 23 way D for video?

[Merlin]

@ rkauer

Can you post a bill of materials please, so we all know what to get?

Thanks

[rkauer]

OK.

I'll dig out the schematics again to make a BOM and even correct it. Coming in this very week, I promise.

[chiark]

Cool - I don't feel guilty about reanimating a thread from the dead

[kipper2k]

After finishing the RGB to S-Video adapter, i want to getting a RGB - Component adapter up and running too. I haven't seen much to do about component output, does anyone have any schematics or any more info on this besides whats already covered here.

Thanks

[rkauer]

K, I'm remaking the whole thing using the MH6722 (very fast quad-op-amp).

Think it will be ready in a couple of days. Old design proved itself reliable (prototype), but this newer will be better.

New: just two IC on the board, less footprint, less power consumption. Easier to fit inside the A520 case (or into any case you wish).