Tuesday, January 12, 2010
Chapter 2 - Exercise 6
Exercise 6 is fairly easy to perform, but don't ignore the reading. There's a LOT of information in these pages, including a detailed discussion on the types of switches and an introduction to schematics.
I'll admit that schematics have always confused me, but so far I'm understanding what I'm reading... we all better understand them because future experiments in the book are only found in schematic form, no full-color pretty drawings showing circuit setups... so be warned.
Now, regarding Exercise 6... I setup the circuit with the two switches starting in the same positions shown on page 44. My photos here will show you how the LED is lit... then when one of the switches is thrown, it turns off... and then when the other switch is thrown, the LED lights up again.
While I was at it, I took voltage readings that you can see in the other photos. The total voltage provided by the batteries was 6.4V. The voltage across the resistor was 4.4V and the voltage across the LED was 2.0V. This tells me that the two switches have negligible resistance and are simply letting the current pass through when in specific positions. If the voltage on the LED and resistor didn't add up to 6.4V, it would be a reasonable guess that the switches have some sort of internal resistance... but that's not the case.
Finally, although I've used my Kronus wire strippers a lot in other projects, here's a closeup of how it works. I've inserted a green 22 gauge solid core wire about 1/4" - when I grip the handles and squeeze, the two top metal pieces come together and bite down, stripping off the end of the wire... very cool. My only complaint is that sometimes the 22 gauge wire gets pulled out of the sheath... I think this is an issue with smaller gauge wire. I think I'm going to use my other plain wire strippers for future exercises that involve 22 gauge wire.
That's about it - having two switches with screw terminals was nice - I only needed to use gator clips to attach the resistor to the LED and the positive battery wire to the resistor... all other wires were screwed down tightly and didn't come apart.
Tomorrow I'll post my experiences with Exercise 7, including a question for my USA readers... the best answer will win the responder a shiny new blue Maker's Notebook. (I'll let me readers plus one or two specialists I rely on help me pick the best answer. Sorry, non-USA readers - postage on this thing is likely to be a little high.)
CLARIFICATION: The question will require use of the book, sorry. If you don't have the book yet, don't sweat it. I'm going to leave the "contest" open until January 31st and pick a winner on Feb 1, 2010. This should give those who have ordered but not yet received their book a chance to respond.