Creating Component Video inside the Amiga

[rkauer]

Hi ppl.

Reading other thread, I had an idea: since the Amiga (at least the ones who have composite out) have "almost" all signals present (Y, C, R, B), I think there is only one thing to do...

We need to "create" the missing signals!

Since the missing ones are only Pb (difference between Y and blue) and Pr (same, but red), those are just the necessary to make a "YUV" out inside the Miggy!

So the question is: can I create the necessary signals using the R, B and Y, plus a pair of low noise op-amps?:confused

[Zetr0]

@rkauer

you would need a small component IC from the RGB to actualy pump out the YPbPr encoded signal... i shall hit my tech specs.

[alexh]

You've got YC though for SVideo, a couple of wires and voila.

[rkauer]

@rkauer

you would need a small component IC from the RGB to actualy pump out the YPbPr encoded signal... i shall hit my tech specs.

That's what I mean. Using a pair of op-amps, configured to gain=1, and using the differencial ins, I thnik we can make a winner!

YUV (Y-Pb-Pr) is only those 3 signals. Since R, B and Y are present, it's just a matter of generating the two diff signals to achieve Pb-Pr.

And Alexh is right, YC is already in there. But I don't want S-VHS (=super-video, as someone can say), but component.

[alphonsus]

Sounds interesting - let me know how you get on!

[Zetr0]

@rkauer

hmmm this is VERY interesting.... tell me how i can help you :) got an idea on what if any specific OPAMPS

[microslave]

While reading this thread I remembered a youtube video I recently watched and which is somehow related: http://de.youtube.com/watch?v=LDP8cvIXtFY
But speaking for myself, I wouldn't DARE cutting my A1000 case and fumbling around with the interiors (as a owner of 2 left hands) :laughing
Nevertheless, this video's really fascinating, so take a look... :cool

[rkauer]

While reading this thread I remembered a youtube video I recently watched and which is somehow related: http://de.youtube.com/watch?v=LDP8cvIXtFY
But speaking for myself, I wouldn't DARE cutting my A1000 case and fumbling around with the interiors (as a owner of 2 left hands) :laughing
Nevertheless, this video's really fascinating, so take a look... :cool


Not sure about the A1k, but in the 1200 we always have that back cover to create custom connectors. And the youtoob video is for S-VHS only. My goal is Video Component (YUV).

Back to the topic: I wonder if feeding the each op-amp positive input with R or B (before the CI clamp circuit to match the propagation times), then put Y in the negative inputs and set the gain to "1" with proper retrofeeding is enough to generate the Pr and Pb signals. Am I wrong?

BTW: I am left-handed (my right hand is useful only to hold something or when typing or playing in keyboards (I'm an ex-musician, too).:D

[Zetr0]

@rkauer

my friend, this is moving away (quickly) from my little knowledge and into the realms of RESEARCH :D

if you can tell me what you need, if i have i will post it :D

[rkauer]

@rkauer

my friend, this is moving away (quickly) from my little knowledge and into the realms of RESEARCH :D

if you can tell me what you need, if i have i will post it :D

Thanks, Zetro.

My only concern at the moment is what op-amp I'll use. Need to be very cheap and with very low noise.

Then I'll start the research on the little copper board.:guru

[Zetr0]

well i have been toying with the 8073 tripple line Op Amps for boosting the RGB, but there is also another on the tip of my fingers that cannot remember... thats arround $4 each... and is a quad OpAmp... its slight higher rated than the 8073 too....

damn it.... wheres my brain this week.

[alphonsus]

http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=12224&doy=16m4

http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=2856&doy=16m4

and several other quad op-amp packages. Not that I know which one you really need.

[rkauer]

http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=12224&doy=16m4

http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=2856&doy=16m4

and several other quad op-amp packages. Not that I know which one you really need.


A simple dual op-amp will be enough for the hack, thanks Alphonsus and Zetro!


We only need a way to use retrofeeding and differential at the same time on each op-amp to make the hack works. Plus I need to remember how can I set the gain to 1, since any amplification of the signals are not desired (really bad colour distortions).

[alexh]

And Alexh is right, YC is already in there. But I don't want S-VHS (=super-video, as someone can say), but component.
S-VHS is a type of video cassette recording system.

Svideo (Separate Video) is an analog video interface specification.

Super-video is erm.. a slang English phrase first used in the early 1970's, by exceptionally "camp" people at the end of home movies? ;)

[Zetr0]

....
Super-video is erm.. a slang English phrase first used in the early 1970's, by exceptionally "camp" people at the end of home movies? ;)


:shocked

You know this how..... were you staring in them again.... you know you will make Dreamcast Kat Dizzy very jealous!!!


anyway my brain died.... is there an OP AMP 97xx tripple or quad line ? i cannot remember... i cannot find it in my favs.... it was $4 from digikey i think... it might help RK out here....

[rkauer]

:shocked

You know this how..... were you staring in them again.... you know you will make Dreamcast Kat Dizzy very jealous!!!


anyway my brain died.... is there an OP AMP 97xx tripple or quad line ? i cannot remember... i cannot find it in my favs.... it was $4 from digikey i think... it might help RK out here....


Since I'm on this side of the pond (Brazil, remember?), I'll make contact with some local distributors too see what I can put my hands on.

The AD8072 (dual op-amp) sounds nice to me.

[Calgor]

I know nothing about constructing hardware, but not sure if these equations in this post for converting to YUV from RGB will be relevant for you:

http://eab.abime.net/showpost.php?p=402395&postcount=5

[OddbOd]

Perhaps a circuit like this one (http://www.epemag.wimborne.co.uk/1206.htm) is the sort of thing you are looking for? Let me know if you would like a copy of the article.

[Zetr0]

@OddbOd

indeed, i would like a copy of the article :D

[OddbOd]

Zoned for your reading pleasure, hope you find a suitably devious use for it.

[Zetr0]

YUMMY"!!!!!

thankie :)

[rkauer]

@OddbOd

indeed, i would like a copy of the article :D

Please, send a copy of the article to me 2!:D

Since the idea of a very cheap YUV out is becoming in a vast project (those resistor nets to make the appropriate signals are now puzzling me.

More updates to come after some research.:guru

EDIT: in the zone? Wow, that was fast! Thanks a lot m8!

[rkauer]

So far, so good.

The schematic is good enough to achieve YUV from the RGB video out, so the hack will be good to all Amigas, not only 600/1200.

My only concern is about -5V, since, AFAIR, the RGB port have the -12V rail (easy to decrease it to -5V with a LM79L05) in 500/600/1200, and -5V in the other models (pin 21 on the RGB connector).

The main goal is make an YUV converter inside an A520 box, using the case and the rare 23 pin DB-sub.http://www.amigabr.org/uploads/smil47e876b1cbff5.gif

[adonay]

So far, so good.

The schematic is good enough to achieve YUV from the RGB video out, so the hack will be good to all Amigas, not only 600/1200.

My only concern is about -5V, since, AFAIR, the RGB port have the -12V rail (easy to decrease it to -5V with a LM79L05) in 500/600/1200, and -5V in the other models (pin 21 on the RGB connector).

The main goal is make an YUV converter inside an A520 box, using the case and the rare 23 pin DB9-sub.http://www.amigabr.org/uploads/smil47e876b1cbff5.gif

I always thought about buying a small pre made pcb like http://www.arcadeshop.com/rgb/rgb2palv4.htm And solder the RGB wires inside my miggy never got this far though as i have orderd a new tv box and may not need this then ...

[rkauer]

I always thought about buying a small pre made pcb like http://www.arcadeshop.com/rgb/rgb2palv4.htm And solder the RGB wires inside my miggy never got this far though as i have orderd a new tv box and may not need this then ...

USD95.00 for a converter? That's what I call a rip-off!

My humble design don't go far as USD40.00 if I can reduce the price. I'll make contact with the YUV converter author to make a board based on his design.

And using a dead A520 case for the Amiga "feel". Since YUV is universal (works fine in any TV set), I don't even need two versions of it (PAL and NTSC).

Maybe only a special version for "low-end" Amigas and "big-box" ones (difference in the 21th pin).

[rkauer]

Updating the design:

I found a very cheap chip: LF412. It is a dual op-amp very capable, but this not avoid other hack guy to use his own preferred chip.;)

For the -12/-5 V problem: no problem at all!. Just use the pin 21, not bothered if it drops -5 or -12V. Just use the pin 22 (+12V) for "low-end" Amigas and pin 23 for big boxes. Phook! Why bother with regulated power lines when they are already present? Dumb me!:banghead

More updates to come...:guru

Zetro, I need some feedback about the design so far. Since I'm learning to use ExpressPCB (Eagle isn't easy to use and AmiCAD is too slow...). Can I send you a hand-drawn scan to you?

[Zetr0]

@rkauer

indeed send away (you have my email addy ?)

i can render them in eagle for you and post them back to you :)

I have to admit, eagle is a pain to get into its way of doing things, but once you sussed it its pretty nippy.

[rkauer]

@rkauer

indeed send away (you have my email addy ?)

i can render them in eagle for you and post them back to you :)

I have to admit, eagle is a pain to get into its way of doing things, but once you sussed it its pretty nippy.


I already have your mail, of course, m8.

Express PCB is doing the job in a more quickly way for me (the learning curve is very fast). But I want a second opinion and a "test dummy";) for the design. And another guy to help developing the board is always welcome.:great

Shame those circuit programs don't talk with each other.:crazy

I'm thinking in put a selector switch in the under side of the board (to not ruin the A520's case) for Wedge-BigBox (-12/-5V). In truth, the selector will catch +12 or +5V for the Op-AMPs. I'll keep the resistors net in the schematics (so I don't need to burn my brain with useless calculation).

I'll send you the PCB-express PCB I designed so far to your appreciation, too. "Saúde!" (=cheers! in brazilian portuguese).http://www.amigabr.org/uploads/smil47e876b1cbff5.gif

[Stedy]

Guys,

A couple of points to note.

The op-amp for the video needs to be fast, in the region of 100-300MHz. The LF412 is most definitely not suitable.

A single pixel of video last 67ns (768 pixels/52us active video time). Taking the worst case, going from black to peak white, or vice versa, the signal needs to transition from 0 to 700mv in about 10 ns and settle in a few ns.

The LF412 takes 2 us to settle to 0.01%, this is the time for 29 pixels. The MAx4451 (in the converter circuit) will settle in less than 16 ns.

The slew rates are also important, the LF412 has a rate of 10V/us, the MAX4451 has a rate of 485V/us.

If you use the LF412, you will most likely have fuzzy text.

Also with any video amplifier, or amplifier circuit in general, be careful you do not create unintended poles in the feedback network of the op-amp or it will oscillate. Always buffer the op-amp output with a series resistor, 75R in the case for video and ensure that the Feedback pole of the op-amp is outside of the bandwidth of the op-amp.

Layout the PCB with plenty of ground plane/tracking to reduce capacitance. Never use a socketed part for a video amplifier. The capacitance of the socket (10-20pf) will give you grief.

Oh, this circuit may have an issue with NTSC video.

With NTSC video, black level is 54mv +/-36mV, for PAL, as used in Australia where the circuit was designed, black level is 0-35mv. Worst case, black may not be completely black! With some LCD TVs you may not notice!

A system I have worked on used the MAX4451, we had a few issues with ground bounce due to PCB layout and capacitive loading, which were tricky to fix. Just trying to pass on some lessons learnt.

[Zetr0]

@Steady

:bowdown As awlays Awesome! :bowdown

thanks for the info :)

[rkauer]

Guys,

A couple of points to note.

The op-amp for the video needs to be fast, in the region of 100-300MHz. The LF412 is most definitely not suitable.

A single pixel of video last 67ns (768 pixels/52us active video time). Taking the worst case, going from black to peak white, or vice versa, the signal needs to transition from 0 to 700mv in about 10 ns and settle in a few ns.

The LF412 takes 2 us to settle to 0.01%, this is the time for 29 pixels. The MAx4451 (in the converter circuit) will settle in less than 16 ns.

The slew rates are also important, the LF412 has a rate of 10V/us, the MAX4451 has a rate of 485V/us.

If you use the LF412, you will most likely have fuzzy text.

Thanks for the information, Stedy! So, back to MAX4451 (or other cheaper solution). The hunt restart.:crying


Also with any video amplifier, or amplifier circuit in general, be careful you do not create unintended poles in the feedback network of the op-amp or it will oscillate. Always buffer the op-amp output with a series resistor, 75R in the case for video and ensure that the Feedback pole of the op-amp is outside of the bandwidth of the op-amp.

Layout the PCB with plenty of ground plane/tracking to reduce capacitance. Never use a socketed part for a video amplifier. The capacitance of the socket (10-20pf) will give you grief.


I know about parasite capacitances, thanks, m8. Also BIG ground planes are present in the board design ;-)

I'll keep the resistor network used in the original design (from the zoned schematic), with a major re-design to match A520's dimensions (I have two dead A520 in here). And 3 hopeless A500 (lots of fried ICs, broken cases and lacking chips) and one A600 (the naive* user used a wrong power connector and fried everything!) to butch the DB23 connector.

*"naive" <- put your favourite swear here


Oh, this circuit may have an issue with NTSC video.

With NTSC video, black level is 54mv +/-36mV, for PAL, as used in Australia where the circuit was designed, black level is 0-35mv. Worst case, black may not be completely black! With some LCD TVs you may not notice!

A system I have worked on used the MAX4451, we had a few issues with ground bounce due to PCB layout and capacitive loading, which were tricky to fix. Just trying to pass on some lessons learnt.


I think "almost perfect" is better than fuzzy (like internal modulator/A520). And NTSC users normally don't get full quality colours, anyway.;-)

But I think it is just a matter to use a bit bigger luminance feedback resistor to drop the voltage levels a little, but then the white will become not that white any more...

[rkauer]

Dropped the MAX4451, since it cannot be fed in a +/-12V arrangement. Looking for a better part

[Stedy]

A couple of suitable op-amps, available from Rs-components and other good distributors.

AD818 single device but cheap.
AD829, single device, through hole but nearly 3X price of AD818.
AD8013, triple amplifier, through hole mount. Reasonable price. Single power supply.
AD8011, single amplifier, +/- 5V supplies.

What is to stop you using a 7805/7905 linear regulator pair as in the original design?

Not many video amplifiers operate off +/-12V. ADSL amplifiers might but they may not be suitable for this application, check settling times. Also these parts run hotter.

Adding linear regulators helps to filter out noise on the digital power bus of the Amiga. for the 50mA that the circuit will take, small linear parts will suffice.

DB23 connectors are available but you have to look hard. I know of one place in the UK and 1 in Ireland that stock them.

Bye,

Ian

[rkauer]

A couple of suitable op-amps, available from Rs-components and other good distributors.

AD818 single device but cheap.
AD829, single device, through hole but nearly 3X price of AD818.
AD8013, triple amplifier, through hole mount. Reasonable price. Single power supply.
AD8011, single amplifier, +/- 5V supplies.


Hello Ian. I'll watch those op-amps more closely. Thanks.


What is to stop you using a 7805/7905 linear regulator pair as in the original design?

Not many video amplifiers operate off +/-12V. ADSL amplifiers might but they may not be suitable for this application, check settling times. Also these parts run hotter.


I notice the problem when searching for parts. The problem is the 22th pin in the RGB port. It supplies -12V @10mA max (in wedge Amigas, like A600), and I'm intending to put the converter inside an original A520 case (for good Amiga-looking).


Adding linear regulators helps to filter out noise on the digital power bus of the Amiga. for the 50mA that the circuit will take, small linear parts will suffice.

I was thinking in put a pair of 78L05/79L05 in the design, but since big box Amigas provide +/-5V directly in the connector, why bother? If the noise becomes a problem, I'll add the 78/79L solution. Or an inductor/capacitor network to filter it.


DB23 connectors are available but you have to look hard. I know of one place in the UK and 1 in Ireland that stock them.

Bye,

Ian


But I'm in Brazil! No way to grab those components here, only butchering really dead Amigas and accessories.

Hmmm... Ian Steady... Are you Ian Stedman? Good to see you here, m8!:bowdown

[Stedy]

Hi


Hello Ian. I'll watch those op-amps more closely. Thanks.

I notice the problem when searching for parts. The problem is the 22th pin in the RGB port. It supplies -12V @10mA max (in wedge Amigas, like A600), and I'm intending to put the converter inside an original A520 case (for good Amiga-looking).

I was thinking in put a pair of 78L05/79L05 in the design, but since big box Amigas provide +/-5V directly in the connector, why bother? If the noise becomes a problem, I'll add the 78/79L solution. Or an inductor/capacitor network to filter it.


The other option is to use just the +12V supply and create -12V with an inverter like the ICL7660 or the MAX765.


But I'm in Brazil! No way to grab those components here, only butchering really dead Amigas and accessories.


It is possible to buy the cable mount/solder bucket connectors but the right angle PCB mounts ones are as rare as scandoublers! :blased


Hmmm... Ian Steady... Are you Ian Stedman? Good to see you here, m8!:bowdown


One and the same.

[rkauer]

Thanks a lot for the input and suggestions!

So far I re-design the whole thing.

Now it uses 3 AD818 (affordable chip - less $$$ spent!:great), one 78L05 and one ICL7660 (for negative power).

The entire schematics resides now only in my mind (dangerous place! Beware!). I need some time to put it in Express-PCB (boy! I'm getting good on this little program!). After creating the design, I'll save it to .jpg to show it here.

Vero board, here I come!http://www.amigabr.org/uploads/smil47d44bc252666.gif

[rkauer]

Thanks a lot for the input and suggestions!

So far I re-design the whole thing.

Now it uses 3 AD818 (affordable chip - less $$$ spent!:great), one 78L05 and one ICL7660 (for negative power).

Dropped the ICL7660, it needs constant current to run stable. Swapped for a MAX764 (1 inductor, easy to buy). 4 AD818 now.


The entire schematics resides now only in my mind (dangerous place! Beware!). I need some time to put it in Express-PCB (boy! I'm getting good on this little program!). After creating the design, I'll save it to .jpg to show it here.

Put the design in a safer (read: out of my mind) place. Submitted to Keith for bug tracking (aka crash-test). Now the board is fed by a LM78L05 and the DC-DC converter (MAX764).

Soon a schematic picture here.http://www.amigabr.org/uploads/smil47d44bc252666.gif

[rkauer]

OK, here it is.

Sorry for the ugly-ass hand draw.;)

[Zetr0]

LOL thats still 100 times better than my scrawling!!!!

[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!


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

[rkauer]

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...:sleep

[Zetr0]

@RKauer

my friend, they have them on www.futurlec.com infact click here for direct link (http://www.futurlec.com/cgi-bin/search/search.cgi?search=max764)

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]

@RKauer

my friend, they have them on www.futurlec.com (http://www.futurlec.com) infact click here for direct link (http://www.futurlec.com/cgi-bin/search/search.cgi?search=max764)

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!:banghead

Sigh! Back to the express-PCB...:guru

[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]

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.:mad

[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 :D

[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.:nervous

[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 :cool

[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 :D - I don't feel guilty about reanimating a thread from the dead :D

[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).

[kipper2k]

Excellent,

Thanks, Cant wait to play :)

[dannem]

rkauer! Did you ever finish the design on this one?

[rkauer]

Yes, but I'm unsure where I stored the schematics. Never did the board routing.