Published by rich on
Saturday, July 26, 2008 - 19:00:04
- Filed under Robots and Electronics, Other Fun Stuff
I’ve mentioned previously how much I like Pololu’s Baby Orangutan AVR Atmega-based robot controllers.
I use them pretty much exclusively in all my robotics and other electronics projects.
Specifically - they’ve saved me an untold number of hours in my ongoing translational drift / melty brain combat robotics effort.
You get a whole bunch of stuff packed into a tiny 1.2” x 0.7” board. In fact, for many projects you won’t need any additional circuitry besides sensors, motors and other goodies.
First - why Atmel?
- Pretty popular with hobbyists - so there’s lots of info out there
- WinAVR provides a decent free C development environment
- BascomAVR provides a free (size limited) basic compiler demo - or you can buy the full version for $120 (this is what I generally use)
(Yes, I’m a big fan of basic. For better or worse, it’s actually what the SpamButcher spam blocker program is written in.)
Pololu recently updated the Baby Organgutan. I haven’t sampled the new version yet - but the changes are pretty straight-forward including an upgraded voltage regulator and motor controllers.
Here’s what you get for $29.95 ($24.95 for an Atmega48 4k version):
- ATmega168 AVR microcontroller (16k flash, 1K RAM)
- ISP programming port
- Voltage regulator (5v to 13.5v input)
- Dual motor drivers (now good for 1 amp / channel continuous)
- Potentiometer
- 2 LEDs (one power, one user controlled)
- 20 MHZ crystal
- Additional support circuitry that helps to prevent brownouts and provide accurate analog readings
Those last two items are more important than I was really aware of. I hit a lot of problems with a board I recently designed because I failed to include all the right capacitors, coils and resistors in the right spots.
While I think the intent is to solder the pins in facing “down” and mount it in a socket - I like to solder mine with the pins facing up. This lets me wire-wrap right to the board:
If you get pins that are long enough - you can still solder a few of the pins to attach the Orangutan to another board. Or, you can just use mounting tape to hold it down.
Don’t underestimate the value of the motor drivers - they’re not just for motors!
I’ve used them to pulse high-wattage infrared LED’s and even drive a speaker.
To program the board you’ll need Pololu’s Orangutan USB Programmer or Atmel’s own programmer.
Yes, you might be able to put these components together yourself for a little less money - but how big would it be when you finished? How much time would you have to spend to wire it up?
For most small robotics projects the Baby Orangutan is a logical starting point. Pololu’s other Orangutan models are worth looking at for more advanced projects.
Published by rich on
Saturday, July 12, 2008 - 20:10:51
- Filed under Other Fun Stuff
I’ve been spending about $80 / month on water - a lot for a single guy.
I attribute this mostly to my long showers.
I spend a lot of time contemplating the SpamButcher anti-spam email system while in the shower. You could say I do some of my best work there.
I speculate that I’m spending about $64 each month on showers alone.
As part of my recent crackdown on spending - I wanted to see if I could do anything about this.
I already had installed an adjustable water restrictor on my existing 2 gallon per minute (GPM) showerhead. You can get one of these at the local hardware store for about $5.
I had it restricted back to only about 1.8 GPM. If I restricted it any further - it just didn’t feel satisfying.
(You can easily measure how many gallons per minute you’re using by timing how long it takes to full up a container of known volume)
So - I went to Home Depot and picked Delta Amplifying Shower Head for $12.75.
The packaging claimed it produced a shower that felt like 2.5 GPM while only using 1.6 GPM of water.
To my surprise - it works exactly as advertised!
While the head looks like it will just shoot a straight jet - it actually produces a nice pulsing widely dispersed stream - like a heavy rain.
In fact - I’m able to crank my restrictor down to 1 GPM and still get a fully satisfying shower.
If my guestimates are correct I’ll be:
- Using 44% less water for showers
- Using 35% less water total
- Saving about $28 a month
So this new shower head will pay for itself in about 2 weeks (3 weeks if you count the cost of the restrictor). That’s a pretty good return on investment.
In other money-saving news - I recently located the Quicken Starter Edition 2008 free trial, the Quicken Deluxe 2008 free trial, the Quicken Premier 2008 free trial, and the Quicken Home & Business 2008 free trial despite Intuit’s best efforts to hide them.
Published by rich on
Wednesday, July 9, 2008 - 20:26:07
- Filed under Other Fun Stuff
I’ve used eBay many times over the years as a buyer - and have had about 95% good luck.
I just did a big spring cleaning, had some stuff of moderate value - so I decided to try selling.
1. Antique typewriter
Sold fine and the buyer paid promptly using PayPal. However, I lost about $8 in shipping and another $8 or so in packing. Since the item only sold for $31 - I only made about $15 total (before listing fees).
Not really worth my time.
Lesson: Don’t bother selling difficult to pack / heavy items of only moderate value on eBay. It’s hard to accurately account for all costs and still have the shipping price seem reasonable.
2. Another typewriter
This transaction also went fine - selling for $26. I again lost a few bucks on packing / shipping. Not worth it.
3. An old Macintosh 128
I managed to score $158 for this! I lost about $15 on shipping / handling. Still, worth my time.
I was worried as the buyer had “zero feedback” (no track record) - but they promptly paid using PayPal.
I did get a number of inquiries on this (and other auctions) from people wanting me to ship to various places around the world. This sent me searching the web for different shipping calculators. Of course, none of these people actually placed bids - so ultimately they were just wasting my time.
Lesson: If you’re not willing to offer international / alternative shipping - make that clear in the listing.
4. An R2D2 oragami-style 3d model
This item was large and heavy, but I was hoping it would bring in a few hundred dollars.
I’d listed shipping as $35 - which I figured out was significantly too low - but too late to change the auction. I would probably end up eating about $20 in shipping costs (not to mention the $20 or so I’d already spent boxing it up).
Annoyingly, one bidder emailed me saying that if I didn’t charge “actual shipping” he’d withdraw the bid he’d already placed.
When the auction finished - I was frustrated that it only came out to $87. That’s how it goes though.
But - it gets better. The winning bidder emailed me wanting to know the total so he could cut me a cashier’s check and send it via snail mail.
The auction was setup as taking PayPal for payment - nothing else.
The bidder claimed to be completely new to eBay - and didn’t have a clue. Having “zero feedback” - he had no track record. This could also mean he had really ditched his prior account due to negative feedback.
Fortunately, that’s not a problem any more as eBay now only allows positive feedback to be left on buyers.
In fact, if you say anything bad in your positive feedback - eBay may suspend your account.
However, buyers can still leave negative feedback on sellers. No, I’m not making this up.
You could even say eBay is encouraging buyers to leave more negative feedback.
But, back to the story,
I (politely) told the would-be R2D2 buyer he had 48 hours to get himself a PayPal account setup and pay me - or I’d have to relist the item.
The 48 hours elapsed without any response - so I relisted the item.
Then, about 18 hours later the original buyer contacts me and tells me he’s trying to get PayPal setup - and is going through linking it to his bank account (a process that takes 3 days). It also means that he would be trying to pay via a transfer - taking another 3 days.
Sorry Charley.
The new listing wasn’t getting a lot of attention - and I really wanted to get rid of this thing.
So, I cancelled the auction - and gave it away on craigslist.
Within an hour someone showed up to get it. It apparently ended up as a decoration at some kid’s Star Wars themed birthday party.
Lesson: Make it painfully clear in the auction how you expect to be paid and how soon.
Lesson: Consider putting in the item description requiring that “0 Feedback” buyers contact you before bidding. Cancel any bids from zeros who don’t play along.
5. Yet another typewriter
This auction finished 4 days ago and the buyer has failed to respond to any of my messages.
Amazingly - this buyer has 100% feedback! He wouldn’t be the type who flakes out? Right?
Oh, that’s right - feedback on buyers doesn’t mean anything any more.
Screw him - someone from craigslist is driving by to pick up his typewriter as I type this.
6. Cell phone
This item seemed to sell fine - then I got the following message from eBay:
Subject: MC143 A29 TKO NOTICE: Secure your computer ...
We recently learned that someone was using an account to bid on items without the account owner's permission. For this reason, we have canceled all bids on the following listing:
(Listing info....)
All associated fees have been credited to your account. Please note that we're working with the account owner to prevent any additional unauthorized activity.
Unfortunately, we're not able to automatically relist the above item for you. To relist the item, you'll need to use either the Sell Your Item process on eBay, or another listing service.
Huh? I don’t get it. The item description was wiped out - I had to manually relist it.
When I did, I decided to bypass this whole bidding game and make the item Buy it Now only. Further - I priced the phone a bit cheaper than I thought it was worth.
The nice thing about “Buy it Now” is that you can force the purchaser to make payment immediately. The item sold quickly - and I got paid.
Lesson: Save item descriptions in a local file - eBay may decide to kill them.
Lesson: Selling stuff with “Buy it Now” only and requiring immediate payment can avoid many common eBay headaches.
Conclusion
My first experiences as a seller on eBay generally sucked. Half of all auctions I placed went haywire somehow.
I’m not saying I wouldn’t list on eBay again - but I would certainly hesitate.