Day 6: Some Switches

In trying to figure out the best way to attach this most common of switches, I found some tiny rivets that fit the small chassis holes well. But there is no way I could crush them enough to grab the large mounting holes in switch, so I would need some washers with tiny holes in them too, and I then would not be able to remove it without some grinding. Ultimately, I just decided to carefully drill out the holes to 3/32" which nicely fits a #2-56 bolt. I have plenty of hardware that size. BTW, sorry to the metric people, but these 80's mechanicals for electronics are all imperial. I am reluctant to do the conversions because I am not totally sure if hardware in the size I convert to is available or would work. Lets just say that is a bit over 2mm. Anyway, the edge of the hole is very close to the cut-out for the switch, but it works. Between the TO-3 voltage regulator and the old-school switch, the robot is getting quite a retro vibe. I am not sure that I am really feelin' the red now though.

To fix the counter-rotating wheels, I swapped one wheel onto the opposite axle for the motor, then rotated the motor in the case so that the wires come out in the right spot, and moved the motor mount to the opposite side. Once I realized that my longer motor mount screws were touching the voltage regulator case again, I had to take both motor mounts off and switch the screws around. I guess I could have just swapped the positive and negative wires, but I wasn't sure of the consequences and I didn't feel like soldering. It seems to be set-up properly now, even if the motors are not quite perfectly symmetrical.

As I was starting to wire up ICU on the breadboard, that obviously counterfeit MC14599 was really bugging me. There just aren't any reasonably priced ones available and there is not a cheap CD series equivalent. Then I noticed on the data sheet that the MC14599 is the same as the MC14099, but the former is bi-directional. That's weird because it is only used as an output register in the "Minimal ICU System" which the MC14099 is fully capable of. I can only speculate that the inverted write select input corresponds better with he MC14500B, and saves an inverter. Well, if that is the only benefit, I am going with a real MC14099, and adding an inverter. Purchased.

Busy connecting wires and looking for my breadboard power supply. I decided to use hot glue to affix the ends of the jumper wires to the breadboard and keep them in place. I think it could use this extra help, especially on a moving robot.