04/17/2021 at 16:03 •
I was given a microphone spec:
- Vout (RMS) = 0.25mV
- Zout = 9.5 Ohms
And I wish to use an audio generator to simulate such microphone. This can be accomplished by a voltage divider with the right resistor values.
12/14/2020 at 12:20 •
This week H-A-D featured an article with a home-built racing sim. While watching the video I have seen that the author did many connections on an Arduino board just inserting the wires on the pin header.
I have seen that before on a considerable amount of projects. It's not something I would rely on for a long term operation circuit, then I realized that there is room for a screw terminal shield. (Eagle Files):
11/23/2020 at 02:21 •
The Expert is a Brazilian manufactured in the 80's and it is compatible with MSX standard. It uses a detachable keyboard but it lacks the Caps Lock LED on the keyboard because the 13 pin connector used ran out of pins (even the shield is used as a 14th conductor for GND).
One day I heard about that issue on my favorite podcast, and just for fun I have designed a Caps Lock cartrige for the Expert. Some time later I have added another feature to the cartridge that is not implemented on the computer: a RESET button.
I have designed PCBs for the MSX cartriges before, like the MSXDOS2 cartride that contains a ROM with the MSXDOS2 kernel with some glue logic to perform the bankswitching (the circuit was not designed by me though). Such cartridge allows the Expert - an MSX1 machine - to run MSXDOS2 without a Memory Mapper.
On this sunday afternoon I have merged the two projects and created the Ultimate MSX Caps Lock cartridge:
The PCB and schematics files are available on Github. I have just routed the board, not assembled the circuit yet, sou use it at your own risk.