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Forum Index : Microcontroller and PC projects : PicoBuddy Picomite computer board

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DaveC5
Newbie

Joined: 24/09/2025
Location: United Kingdom
Posts: 11
Posted: 07:33am 01 Oct 2025
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@Volhout @javavi
Thanks for the observation re: the feedback comp cap, I'll add that.

Re: the VGA palette. I like the Windows palette approach suggestions, so the next version will go something like this:



Sticking with the aim of keeping the no. different components to a minimum, this comes within 5% or thereabouts of Volhout's mod using just 390R resistors. It adds an extra one, but has the benefit of using the same value throughout. I can then optimise the BOM by swapping the 3x 470R resistors already on the board (LCD backlight and headphones) to 390R for little practical effect. Changing J15 from a single 2-pin jumper to a 2x3-pin jumper is also no problem and you could wire it to an external switch if you wanted.

If anyone is interested I still have a couple of the bare V1.0 boards left over, free to anyone who might be interested in having a tinker. Happy to post them in the UK.

Also if anyone is interested in the final version once it's finished I'll share it on PCBWay along with the documentation and the BASIC routines for the LCD etc.

Cheers
Dave
 
javavi

Guru

Joined: 01/10/2023
Location: Ukraine
Posts: 516
Posted: 03:32pm 02 Oct 2025
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  DaveC5 said  Changing J15 from a single 2-pin jumper to a 2x3-pin jumper is also no problem and you could wire it to an external switch if you wanted.
 
Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 8156
Posted: 03:49pm 02 Oct 2025
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I keep looking for those switches with horizontal mounting but I don't think they are made. :(  It means fiddling about with little sub-PCBs so I use these:

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
javavi

Guru

Joined: 01/10/2023
Location: Ukraine
Posts: 516
Posted: 09:30am 04 Oct 2025
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@Volhout
Following your advice, I slightly redesigned the palette switch circuit for the PicoMite VGA.
 
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