TG16 AV out

[Tiido Priimägi]

Thanks to Tomaitheous I have a TG16, and me being an RF hatin' European, I quickly RGB modded the beast
I'm using my ultra simple video amps and thus there's some very slight horizontal blurring (muuuch less than SNES though). As you can see on the photo, I messed up a little... TG16 has really poor PCB, traces get loose too easily, just like 32X. A warm tip - don't solder your transistors right on the trace or a via, it'll come off !!! Use some thick trace instead, like the power rail, which is what I did

[RGB32E]

Could you elaboriate as to which connections you made, and the circuit for the RGB amp?  It's not very clear when attempting to decipher the picture... 

[Tiido Priimägi]

RGB amp =>   color signal from the chip to 2SC945 Base, Collector gets +5V and Emmiter is the output. I have no resistors there, but I should have at least one per transistor, since I can see very slight maount of horizontal blurring (much less than SNES though).
Sync signal is composite video form RF modulator part, I also get my 5V there for the video out connector. Sound is taken from 2 spots near the area where the audio signals leave the chip.

[RGB32E]

Ahh... so the same simple transistor amp as posted on mmonkey's site?  The idea of connecting the emitter directly to the RGB inputs is something that seems concerning.    What happens if you connect a 75 ohm resistor and 220uF cap to the emitter output?  Also, it looks like you're connecting RGB from a different spot than the actual HU chip?

[Tiido Priimägi]

The traces I use are directly connected to the video chip. If you put resistors there, you'll probably get too dark image, without resistor, the image is as bright as my MD2 with resistors. You may add capacitors, but I don't think it'll give you anything extra.
The transistor setup is just a regular source follower, high input impedance, low output impedance, you could connect 8ohm load and get away with it if you'd like (though if your transistors are too weak, they get hot and may fry )

[RGB32E]

The traces I use are directly connected to the video chip. If you put resistors there, you'll probably get too dark image, without resistor, the image is as bright as my MD2 with resistors. You may add capacitors, but I don't think it'll give you anything extra.
The transistor setup is just a regular source follower, high input impedance, low output impedance, you could connect 8ohm load and get away with it if you'd like (though if your transistors are too weak, they get hot and may fry )

Hmm... the last time I tried building an RGB amp for the TG16... it didn't go so well... and that old system didn't output RGB anymore (I think I somehow swapped 5VDC with GND  ).  So, how come you're using a stripped down circuit of this?  I was asking about the additional components as they compare to this circuit.

[Tiido Priimägi]

I just cut corners whenever possible, and it turned out that just single transistor with no additional components gives decent enough video quality. If i'd add all the additional components like on the schematic, I'll probably get no more slight horizontal blurring...

[papa_november]

I tried the mmonkey amp design, and all I got was a blurry picture that almost looked worse than composite.

The "proper" amp design is really complicated for something that has to be that small. It took countless frustrating hours to get it together on an old breadboard and I still don't trust it enough to even test it. I'd love to see instructions on how to do it better (or better yet a pre-made blank PCB for the thing).

[RGB32E]

I tried the mmonkey amp design, and all I got was a blurry picture that almost looked worse than composite.

The "proper" amp design is really complicated for something that has to be that small. It took countless frustrating hours to get it together on an old breadboard and I still don't trust it enough to even test it. I'd love to see instructions on how to do it better (or better yet a pre-made blank PCB for the thing).

Well... Lawrence built one and it worked!


I think I'm going to build the full circuit again.  I purchased a new set of NTE85 transistors (NTE's equivalent of the 2SC1815).  The video amp will have plenty of space in my turbo booster!