Finally started the process of getting my counter off the breadboard and onto a PCB. I am just wiring it by hand, no etching -- but I really need to learn how to use Eagle & etch my own boards, because I am quickly losing my mind/patience/eyesight soldering these wires by hand..
In the basement with Michelle's machine :-p It's so very cute! I want one of my own. One day. Rev B Black Macbook..
This is my week off before ———. Eek! Picked up my last check from ———.. right into the bank and no doubt will be bill fodder. Gurp.
Revisiting my counter circuit. I found how to 'debounce' (mostly) the connection, the 555 (which I already knew) and a capacitor + resistor in parallel connected in series to the trigger switch. The cap absorbs excess 'switches' (as it charges) and the resistor discharges the cap.. or something like that.
So now I needed a reset button to bring the counter back to zero. The 7490 has a pin that when removed from +5v resets the counter. To build a reset switch, I needed either an (a) normally closed momentary-open switch or (b) a NOT gate.
I found a nice TTL NOT circuit here:
http://www.play-hookey.com/digital/experiments/ttl_inverter.htmlLiterally, transistor-transistor. I used 2N222As instead of the 2N4124s. Works like a charm. Now all I need is a tilt switch and I'll be ready to move it off the breadboard and onto a PCB. Wh00t!
After I finish this, I think it would be neat to do the same thing again but this time with a PIC or an Amtel tiny micro, just for fun. I would like to use something I can program easily w/o having to spend $$ on a special programmer. The miniPOV kit I have has a parallel port on it, and is programmable thataway, so ... that might be the way to go. I'd also want to find a way to drive multiple 7-segment LEDs with a single chip.. If there was a "two-BCD-in-to-two-7segment-out" chip, that would work for me ...
I have a DSL modem that periodically stops modeming. I've upgraded the firmware to the latest rev(s), double-checked power connections, and prayed, but to no avail. A power cycle solves the problem, but eventually it fails again. There doesn't seem to be a pattern to the failure, either; hot weather, cold weather, it dies.
It would be nice to be able to powercycle the DSL modem when it failed. X-10 was the first obvious choice, but my previous experiences with the "bottlerocket" stuff showed that it was't all that reliable. Besides, it wasn't much as trying to do it yourself..
I wanted to learn how to drive things from the parallel port. So I first figured out how to turn an LED on and off.
Next: drive a relay. I would have liked to have taken power from the parallel port, but it was not reccomended. Used an external 9v battery to open & close it.
Interface to the parallel port: had some DB9 <-> DB25 cables with RJ11 in between. Found a DB-9 female connector for the controller side.
Finally, the hookup: two female power plugs, and a male <-> male connector. Relay between the power plugs. Power source on one side, and male-male cable to the modem on the other.
Then: what to put it in? Found an 8mm tape case.