I finally got around to a bit more guided testing of my conductive ABS plastic this week, thanks to some direction from /u/eb86 and /u/SaffellBot from Reddit. They suggested to simply measure the resistance of the conductive filament rather than the voltage drop. Eb86 also gave me more direction on measuring the voltage drop with the filaments in series and the multimeter in parallel -- haven't gotten to this yet, but I will soon.
If you haven't read my previous blogs on this subject I'll repeat the disclaimer that I'm a horrible dabbler with electronics. I've no issues with admitting my amateur status at anything (it's a pretty good approach for learning stuff, you know) and I love it if my dabbling inspires other people, but remember -- everyone's responsible for not burning down his or her own house.
This one's a pretty safe experiment. Same 3D printed conductive block that I described in this blog. This time I simply plugged the multimeter directly into the block to measure the resistance. The reading was a pretty steady 143k ohms. That's a heck of a lot more than the 330 ohm resistors that I normally use with my LEDs; I'm surprised the LED lights up at all with the conductive filament in the circuit.
Simple result: while this arrangement does conduct electricity, the resistance is pretty high. (Sounds like I could be describing a marriage at times, huh?)
Yesterday's experiment also resulted in a mystery*. When my 3D printed block is in the circuit without a resistor the LED doesn't light at all. Logic suggests that the resistor and block together would increase the resistance, but no one ever said that logic is key to science, right?
The logical next step (to me) is to print some different configurations of the conductive filament and figure out which offers the least resistance. I've already got this latest one at 90% infill, is the resistance higher or lower with more dense infill? Is the diameter of "wire" a contributing factor? Like a circuit board, perhaps a very thin layer of conductive plastic is better than the wire I have now -- say, .1mm or .2mm as opposed to ten times larger.
More to come...but after I've finished more of my actual work for Film Tycoons.
*By "mystery" I mean, "I don't know the answer to this, though it's very likely that someone with more knowledge of this subject probably sees my mystery as a basic fundamental concept. You can laugh, but you know who you're coming to when you're trying to figure out a SQL database, don't you?