I Made a Small Thing!
So in the Project NEON Sunrise build path, I have realized that I need to do two seemingly mutually exclusive things.
EXCEPT THEY AREN'T!!!!
For the next revision of the board.... once the 6551 is figured out... I want to move up to a 1MHz crystal as the system clock. Except that when I'm doing debugging, I want to be able to control the speed like I can now.
My solution was to design a PCB that would fit into the full can socket, but contain a full 555 astable timer on it. You can see the footprint for the Oscillator in the center, the 555 sits within it.
It's a very simple design, really. I only needed 1 via, which surprised me. I could probably get the footprint smaller still using through hole parts, but I really think I can get it tiny if I use SMDs. The parts list is pretty short, too:
- 1 Oscillator to 555 board
- 2 1K Resistors
- 2 0.01uf Capacitors
- 1 1uf Capacitor
- 1 1M trim potentiometer
- 1 330/390 Ohm Resistor (Optional)
- 1 3mm LED (Optional)
The LED and its current limiting resistor are optional, since it doesn't effect the output signal at all. I like my blinkenlights, so I added them.
The only two design changes I would make right now are to redesign the 1M Pot so it can accept both versions of common 3 leg square based pots, and I need to add the +/- markings to the LED. I know the negative side goes towards the resistor, but it's not totally clear. I like idiot proof PCBs, mostly because I'm an idiot.
As far as testing if it truly works or not, that I won't know until I have the next mainboard to plug it into. But it is functional for now, as far as the status LED shows.
I bought 10 of them because it was the same price as 5 from PCBWay, since they're so small. If you want one, let me know. I'll gladly send it out to you.
I was considering starting something like an Etsy store, if there was enough response for something like this in the homebrew community.