Ignoble Idiocy
"Those who cannot remember the past are condemned to repeat it." - George Santayana
Nobody's perfect, least of all me. Here I intend to record some of my roboting mistakes for my own good. Perhaps you can learn from my errors, or even contribute your own.
Latest Update: 2010-02-04
@ Thu, 2010-09-09 22:35
Picaxe-08 Protoboard F-up
OK, it's been a while since I've had an F-up I felt worthy of this post. This one definitely is.
I'm working on a new project using the Picaxe-08 proto board (pictured below). I had everything working in prototype on a breadboard, and just needed to transfer the circuit to the protoboard to complete the project.
Notice how in the picture there are little lines connecting groups of three contact points? Well, I didn't. Even though I've used one of these boards before, I completely forgot about this very nice feature. I laid out the board assuming none of these contacts were connected.
Surprise! The circuit didn't work. I don't think I fried anything (I hope not), but I've lost at least 2-3 hours work and have to unsolder all my mistakes and start over. Grrrrrrrr.
@ Thu, 2010-02-04 09:40
This one is embarrassing. I
This one is embarrassing. I wanted to film GRAB-E's new features, so I put him on a table and started filming. The only problem was the table wasn't quite bit enough! I knocked the poor guy's head off.
I have video, which I may post if I can get over my mortification.
Update: Alright, video will be available at the link below as soon as YouTube finishes processing it.
http://www.youtube.com/watch?v=UsfdRYBJwSc
@ Wed, 2010-01-20 04:48
Bang goes the driver -- Testing on good hardware is a bad idea
I got some shiny new 75oz-in 24V bipolar steppers (1.4ohm/coil) to replace the weaker 90ohm/coil 24V printer motors on my homemade CNC machine. Today I finally had the time to play with them. My plan was to test out the motor the easiest way I could by plugging in the motor to one of the stepper drivers on the CNC. I took precautions by disconnecting the other drivers, but I overlooked another flaw in my plan -- testing on good hardware. The beautiful thing about using the driver on the CNC is that I didn't have to reprogram my microcontroller -- I just opened up a hyperterminal (yeah I use Windows) and told the motor to go! And it went for a while, and then stopped and shuddered, as if it were too weak to turn. I reached in to investigate.
*sizzle* went the hair on my knuckles as I almost touched the L298 stepper driver IC. "That shouldn't be that hot," I thought. And indeed the driver had gotten quite hot. When I plugged in the old motor, it no longer worked, confirming that the L298 had let out its smoke. Such is testing -- drivers sometimes burn. It was a shame I had decided to test on one of the driver boards I needed for the CNC.
120 minutes later, I had desoldered my spare L298 from a spare driver board (the one I should have used from the start), desoldered the dead L298 from the disabled CNC driver, and the CNC is back in commission. The lesson I have learned is that with new components, do not test on hardware you need. It would have been worth the extra 20 minutes to use the spare stepper driver instead of spending 2 hours fixing the mess I made. oops.
And I probably should have done a quick Ohm's Law calculation of current draw. My motors have 1.4ohms/coil and are driven at 24V, so they want to draw 17A/coil, or 34 Amps with both coils. The L298 was not current limited and can handle 4 Amps.
@ Wed, 2010-01-20 06:36
It wouldn't be nearly as fun
It wouldn't be nearly as fun if you didn't blow something up once in a while.
I wonder how much time is wasted on mistakes we make trying to save time?
@ Wed, 2010-01-20 11:22
How much time we try to save...
@ Sun, 2009-10-18 05:11
Just a minor one
@ Sun, 2009-10-18 05:12
Been there mate, more times
@ Mon, 2009-09-28 21:34
How to get nice blue smoke out of 7805 voltage regulators
Let's see...
Step 1: Find a nice power source - something like 30 V at 400 mA wil do nicely
Step 2: Read the datasheet for the 7805 voltage regulator, TO220 package, very carefully, and find out that the maximum input voltage is 35V
Recap: power source 30V 400 mA v.s. power regulator which takes 35V max => should be safe. Totally awesome right? Let's go on...
Step 3: As a precaution, measure the power source voltage ... hmm 36.5 V but hey that is without load so it should be fine right?
Step 4: Carefully plug in source => board with 7805 regulator, making sure to have the polarity right (protection diodes are for fools ... bah), nice little spark when connecting the power source -> normal because of the capacitors.
Results in:
7805 RIP - Short between all pins => little burned on my testing finger => very good heating element :)
@ Tue, 2009-09-29 01:24
It's too bad you can't smell
@ Thu, 2009-09-24 20:50
Sharp Kicks the Bucket
Picture the scene:-
"LoMoR" experimental Sonar scanner, full gas lets "push it some more" impulse.
Lets connect my only sharp and try infra red probe instead of ultrasonic - quick scan of internet to get the pinouts ....easy
Wired up and noticed the Display dimmed a little (hmmmmm strange i thought) lets turn up the brightness of the display.....fine display good.
Measure the current i thought.... mmmmmm 300ma must be the nice blue display take-ing the current...........
.......... "Sniff sniff" lift IR module up to nose and chin ..... a faint heat was detected on my chin and the whiff of carbonising SharpIR lose-ing its life force and finally kicking the bucket.............
Moral:- never trust the internet for pinouts and test new circuits with low current batteries.........
thank you TinHead and Ignoblegnome for respecting the 1 minute silence , all collections,flower etc will go to charity.