exxos's Atari, Amiga & retro forum

I have started on REV H5 REV C. Mostly this one will include the new amp circuit.

On the left is the new one, on the right the old one. Not much difference parts wise overall. Though this amp will correct the low volume on the X2 MIDI module.

I can't find the OpAmp GS8552 available at DigiKey, Farnell, Mouser, RS Components. Is this an obsolete component? Was it something you already had laying around? Or am I writing it all wrong in the search field again? Can something else be used?

DoG wrote: 28 Dec 2020 17:05 I can't find the OpAmp GS8552 available at DigiKey, Farnell, Mouser, RS Components. Is this an obsolete component? Was it something you already had laying around? Or am I writing it all wrong in the search field again? Can something else be used?

China's finest budget amp... Are you trying to build this circuit ? There will be a PCB with it all on soon anyway....https://www.exxosforum.co.uk/forum/viewt ... =89&t=3759

exxos wrote: 28 Dec 2020 17:07 China's finest budget amp...

Puh... I was not going crazy then. I found it on eBay like you said.

exxos wrote: 28 Dec 2020 17:07 ...Are you trying to build this circuit ? There will be a PCB with it all on soon anyway....https://www.exxosforum.co.uk/forum/viewt ... =89&t=3759

Well, yes and no. I was pre-building it in my head at the moment and checked out all the threads. I was waiting for the Gerbers (hopefully) or ready solder boards? Since postage and customs duty from UK to Sweden will be rather expensive for such a small board.

DoG wrote: 28 Dec 2020 17:12 Well, yes and no. I was pre-building it in my head at the moment and checked out all the threads. I was waiting for the Gerbers (hopefully) or ready solder boards? Since postage and customs duty from UK to Sweden will be rather expensive for such a small board.

I can upload the gerbers if you want to get the PCBs made.. The ones I have are all pre-assembled as in the images. The parts are all LCSC part numbers but you should be able to work out mouser alternatives etc.

exxos wrote: 28 Dec 2020 17:41 I can upload the gerbers if you want to get the PCBs made.. The ones I have are all pre-assembled as in the images. The parts are all LCSC part numbers but you should be able to work out mouser alternatives etc.

I really don't know. I kind of need gerbers with pick'n'place and BOM files as well I guess. So if I order from JLCPCB that they can solder in all the parts. Is that okey?

If ordering blank PCB and ordering a GS8552 from eBay will be rather expensive too. I have to pay import tax/fees from China. Then the rest of the components. Then I might as well order a ready made PCB from you.

I think your cheapest and easiest option is just to get one from my store. Trying to order just a couple of boards isn't going to be very cost effective by the time you have paid for parts, assembly,setup, stencil, PCBs etc. Its probably going to end up costing a lot more. I ordered 30 to keep prices down.

If your not going to use the midi module , there's no use doing this mod anyway.

Yes, I think so too. But I'll wait and order later on.

Do you think adding a decoder for 256k ROMs would be possible in a future revision ?
I built one to use the TOS 2.06, but it uses an expansion slot for just simple address decoding.

olivier.jan wrote: 29 Dec 2020 17:43 Do you think adding a decoder for 256k ROMs would be possible in a future revision ?
I built one to use the TOS 2.06, but it uses an expansion slot for just simple address decoding.

The problem is @Icky and I are in the middle of the FPGA stuff.. which replaces the GLUE which will have 206 decoding on it anyway.. but we don't have time to work on it all... I did consider adding a PLD onto the MB.. but then people would have to solder it themselves which won't end well.. they won't have a programmer (which is expensive) so they will want me to do it all.. I don't have time.

So the external TOS206 decoder is the solution until the FPGA stuff is finished.. but I don't have time to build those currently either.