Ah, gob soldering at its finest. As you might expect the circuit does not work. The wire nest to back of the perfboard leads 5V to the PCBs on the left and runs thru 180 ohm resistors and thru those ribbon cables on their way to my IR LEDs on perf boards underneath the bot. The PCBs are known to work. I removed the MAX232 and pulled the ribbon cables off the IR LED boards leaving only the red power indication LED in series with the 270 ohm resistor, the 100K ohm Pot, and a cap or two across the 5V and GND lines of the regulator. Nevertheless there is only 44 ohms of net resistance between these lines. A 7805 out of circuit measures about 6K ohms. So, I have a mysterious partial short somewhere. Probably a whisker of a stranded wire or some such just barely making contact. When I add the load of the IR LEDs to this scenario the regulator starts to get hot, even though it maintains its 5V output. But, to add insult to injury 4 of the 16 IR LEDs are not lighting up. Could be related to the same low resistance problem, but I wouldn't be surprised if its not due to a 2nd problem with the circuit. I have yet to locate either issue. This same circuit worked like a champ on the solderless bread board. Sigh. I think I just need to abandon this form of circuit building. Its too prone to error. In the new year I am going to focus on making PCBs. I'm also going to focus on using as many SMT parts as possible. A link to an eBay item was posted on the Chibots mail list, 5000+ SMT style parts, and I snagged it for $31. With PCB making skills and SMT soldering skills I figure I should be able to make monolithic and bot specific, as opposed to general purpose modular boards, easily, inexpensively and avoid most the mind numbing details of board module interconnects. (I never seem to have the parts I need to make a decent, serviceable connection.)
Posted by Hello