RGB amp

[fraggore]

just a bit of info for anyone thinking of doing a RGB mod and needs a amp, the simple transistor amp that mmmonke has up on his site here

http://www.mmmonkey.co.uk/console/pce/amp.htm

works a charm and fits nicely into a scart lead done this on a pc engine duo\tg16\and a pc engine duo-r works perfect and its cost about 30p to do and would fit nicely into the console as it so small.

[CGQuarterly]

This is the smallest RGB amp with the fewest # of components that I've seen thus far.  I'd be curious to see how it performs next to the IC-based amp that I use.  If it's just as good, then this is a much easier option.

Chris

[HercTNT]

local techs are aware of this amp. especially thesteve. i would talk with him first before applying such amp as steve knows weather its best for your machine or not. some of mmonkeys mods are not perfect.

[fraggore]

your right some of then are not perfect like the megadrive on tft mod dosent work with all games. i have done this on 3 machines and it works really well it would be interesting to see how it stands up to a IC-based amp, I have only got a iphone but will see if i can take some good pics and post them on here.

[fraggore]

here is a few pics not perfect as it a phone cam taken from my duo-r up close to give you a idea on what it looks like ignore the darker boarders its the camera and 60hrz picture.

To be honest after looking at it again the picture is stunning colours are bright and vibrant its not dark at all plenty of contrast not over the top the picture on all 3 machines is the same.

https://www.box.com/s/03d3c4709737e11fa52e

https://www.box.com/s/2df848381c077b03d46a

https://www.box.com/s/ddc2697f5a88eda2c278

[fraggore]

Here is a small video excuse the outrageous welsh accent.

https://www.box.com/s/e63cdb3ab012b789e76a

[Duo_R]

Cheap and small but not the best

[Drakon]

This amp has been around for ages.  It's probably around 1/2 to 1/3 the power of either an IC amp or a two transistor amp.  The THS7314 is probably the simplest amp you can make.  For the ths amp you need the amp chip, a sop to dip adapter, 1 cap, and 3 resistors, that's all.  I built a couple ths7314 amps then start using the sony cxa series video encoder chips since those encoder chips include a built in rgb amp.  The reason why I switched over is that the cxa chips output amped rgb, s-video, and composite video.

[thesteve]

add 3 4.7K resistors and 3 22uf caps for improved power usage, and less load on the system video chip

[fraggore]

this amp might be putting excess load on the video chip ?.
as for the caps and resistors they will need to go before the transistors yea.

[thesteve]

yes
each transistor gets a resistor and cap in parallel between the transistor and the hudson chip

[fraggore]

ok be better to put it on some strip board then
thanks for the help

[speedlolita]

I followed the guide roughly (result here: http://www.bordersdown.net/showthread.php/115219) and the picture on my LCD TV isn't that solid unfortunately. Looks great on my Commodore 1081 though.

Any links or guides for improving the amp? Thanks. 

EDIT: Would the design in the diagram on this page be a good bet? http://www.gamesx.com/rgbadd/duorgb.php

[fraggore]

you could try swoping the comp sync for comp video that's what i used and seems to work fine connect it to pin 20 on the scart lead i didn't use comp sync wired it just in case but didn't seem to need it.

LCD tv's can has sync problems with old consoles megadrive being the example.

if you switch the comp video for comp sync on the megadrive you can fix a lot of problems but is not perfect and some games at 60hz still don't sync but everything at 50hz does but who wants 50hz right.

[speedlolita]

You know, I was wondering if swapping the sync might work. Would explain (possibly) why it doesn't display on most screens apart from my Commodore.

Do I change how the SCART lead is wired, or which ext port connectors I connect to?

EDIT: Nevermind, found it.

Seems to be working nice, I'll remove the transistor I think.