Monday, September 27, 2010

Chapter 5 - Exercise 32 Update 2

My motor, wheel mount, and other bits arrived today. As with most electronics ordered, there's no paperwork on any of it. I can figure out most of it, but the motor has two unlabeled soldering points... my guess is that it DOES matter which wire goes where as the motor needs to spin in one direction specifically... so... I'll need to revisit the Solarbotics website shortly and see if they have any documentation. Otherwise, The Internets will need to deliver!

I'm going to mark out the cuts tonight for the wood pieces that will make the shell. Not going for accuracy here, so I'll likely just use a handsaw and not flip the old tablesaw on for such small (and thin) plywood.

More to come...

Wednesday, September 22, 2010

Chapter 5 - Exercise 32 Update

My box of parts has shipped from Solarbotics, so it's just a waiting game now for the motor and other bits. I was ready to cut the 1/4" plywood but decided to wait until I get the motor and determine that it can actually be mounted properly, including the hole I'll have to drill for it to drive a wheel.

In the meantime, I took a look ahead to the next robot that will require two photoresistors and two servos. I didn't find what I needed at Solarbotics, so I'm going to keep looking. One thing I'm finding is that servos on a lot of electronics websites come with almost no documentation or so much that you can't make sense of it. For those of you who have not yet started in on Chapter 5, just be warned that there's a fair bit of hunting involved - many of the key parts don't come in either Make: Electronics component kit 1 or 2... makes me think Make might want to consider a final kit titled "Chapter 5: The Missing Bits."

Sunday, September 19, 2010

Chapter 5 - Exercise 31 Final

So, it was a very nice afternoon today (a bit hot, though) in Atlanta - sunny sky, no clouds, no rain. I had a 3 year old helper who was very curious about all the wire and odd bits sitting on the deck table. After running some unshielded copper wire almost 80 feet and tying it off with the recommended polyrope to a tree, I wired up the remaining circuit as shown on page 265 in Figure 5-66.

With high hopes, I inserted my earphone and moved the gator clip down the wrapped bottle, trying each tap.

No luck.

So... I began troubleshooting. First, checked and then double-checked all my gator clip connections. They were good - and every time I clicked on a tap, I'd hear a slight electrical snap in the earphone... kinda like the crackle of static on a radio. Checked each tap again... nothing.

Next I replaced the Germanium diode... I purchased a bunch so I swapped it out two more times, checking the taps. No luck, other than the crackle in the earphone again.

At one point... maybe it was wishful thinking... I honestly think I heard something. Very faint... there just for a second and then gone. I played with various taps and checked all my connections again, but just had no luck picking up anything.

Still... I had fun. And I understand the theory and what SHOULD have happened and WHY. I wish I'd had luck, but I honestly don't even know where the nearest AM broadcast is coming from... living in Atlanta, I've just assumed I'd pick up something!

If any readers perform Exercise 31 and have luck, PLEASE let me know! I'd love to be able to share some pictures or video or even a recording of any transmission you hear with your project.

Up next... I'm going to cut up the parts this week for the robot in Exercise 32... today I managed to swing into the local hardware store and picked up the following:

1 piece of 2x4 1/4" Sandiply (sanded really smooth on both sides) $7.98
1 package of 2" utility hinges (3 per package) - $2.21
1 package 3" diameter felt circles (for under the feet of furniture) - $3.78

Yeah, I know... felt circles? Well, they're 3" in diameter with no center hole drilled and they are very stiff and 1/4" thick. Perfect for the wheels (and, hey... they won't scratch my floor! Bonus!)

Saturday, September 18, 2010

Update and Exp32 Shopping List (Partial)

I'm hoping for some good weather tomorrow ( says YES) so I can head outside and put the finishing touches on Exercise 31... try out my little radio and see if I can pick up any of the AM band radio stations around Atlanta. I hope so... would be a nice surprise.

In preparation for the upcoming Experiment 32 - you know the one if you've been looking ahead in the book like I did! - building the Little Robot Cart. After placing a few phone calls to a few places in Atlanta, I basically decided that with the $6.00 shipping that charges, I'll end up saving some money if I just wait a week or so for the following components:

1. DC Gear motor
2. Disc for motor
3. Two SPDT microswitches
4. 1 DPDT nonlatching relay

In the meantime, tomorrow I'll also be heading up to my hardware store to buy some 1/4" hobby plywood. Yes, I know... the author recommends ABS plastic. But right now I'm not wanting to invest in a plastic bender and I'm comfortable working with wood and have the right tools to cut the proper pieces (see on page 275). Not sure about the wheels, but I'm fairly certain I can find some thin wood wheels at a Michael's or Hobby Lobby that will fit the bill. Otherwise, I'll invest in a 3" bore hole bit and cut my own. I may attach everything with screws or I may go ugly and just stick everything together with superglue or Gorilla glue... not really going for something to enter in a science fair, so not concerned about looks.

If anyone finds these components elsewhere (and cheaper), please share with your fellow readers... in the meantime, I'm posting a screen capture here of the part #s and prices (and quantities) for

Kinda glad to have found some time to get back to the book - I apologize to my readers for such a lengthy delay in finishing up the exercises. Now let's finish this book!