I had an excellent time at SXSW, culminating in the first ever real-life frogger game.
Basically, as I see it, we are becoming so technologically advanced, that we will be seeing more examples of crossovers between the ‘real world’ and the ‘virtual world’
ps. 6th street is a ‘main drag’: at 1am, cars are driving pretty slowly to avoid all the drunk people on the street. Still, don’t try this at home.
I miss the awesome PCB etching setup I had back in the media lab so I decided to put together one here at home.
So far so good, it took 3 tries to get anything decent out of the toner transfer system. I highly suggest the “dowel roll” method for high pressure. All in all, I dont like toner transfer. Photoresist is way superior. However, if you have a laminator apparently everything works a lot better so I’ll be looking into that.
I have some more photos on flickr and a more detailed tutorial later. The etching system is the hardcore MG 7liter. One thing I can say for certain: its more than 7 liters and, secondly, its very hardcore. The regulated heater, thermometer and sparger are awesome and saved me the effort of building a similar system. I etched my 3″x5″ single sided 1oz copper board in about 5 minutes. With a high quality image transfer system (like a simple photoresist) one could definately go down to 10/10mil rule.
I think its way too big though, who the hell etches 8″x12″ boards? I can rarely get consistant exposure over 6″x8″. I may get a different sized tank and keep the nice heater and sparger/manifold/thermometer.
Drilling is performed with a Dremel “multi pro” 3-15krpm in the Dremel “workstation/press” fitted with carbide wire-size drills.
Anyways, thumbs up for the MG “pro etch system” and a no-so-thumbs up for the Pulsar toner transfer system.
This is the first animated gif i’ve made…its pretty simple yet took a bit of tweaking in photoshop to make the two images line up correctly despite using a tripod.
The technology here is ‘persistence of vision‘…when LEDs move fast enough they can ‘draw’ an image onto the retina when the wheel spins. That’s the basis behind both the MiniPOV and SpokePOV (shown here) toys that I designed last year.
I rode this design around last Burning Man. Of course, I’ve adjusted the pictures so they’re ‘upside down’ here for better photographing!
If you’d like to build your own, check out the full instructions on Instructables, hosted by the niftypeople at SquidLabs
I’m behind schedule, so this week we will have 3 chips (from the same family). Instead of reviewing some fancy shmancy ASIC, we’re going to get back to basics with a nice, cheap opamp set.
Cause sometimes you just want an opamp. Nothin’ crazy, just want to add some voltages, maybe amplify something a bit. Possibly do some filtering, or interface to a sensor, or some audio stuff.
Well, my friend, the TL08x’s are your bread & butter.
- 4 MHz gain bandwidth (internally compensated)
- Not rail-to-rail so 8V rail is minimal, a split +-15 is great but even +- 5 is good to go
- Input offset voltage is <15mV
- Input bias current <8nA
- JFET input stage so you’ve got a ridiculous 10^12 (1 Mega-Mega ohm!) input resistance
- <2.8mA/opamp quiescent current
- 13V/us slew rate
- noise figure: 25nVrtHz
Lets compare it to the ye olde favorite, the LM741:
- 1 MHz bandwidth
- Not rail-to-rail
- Input offset voltage: <5mV
- Input bias current: <800nA
- Transistor input stage, >300Kohm input resistance
- <2.8 mA quiescent
- 0.5V/us slew rate
- noise figure: 30 nVrtHz
So the worst case offset voltage is better on the ’741, but the gainbandwidth, the input resistance, input bias current and the slew rate sucks in comparison to the ’081. And the 081 is a little less noisy too.
The dual in 8DIP is a mere $0.64 from digikey, mouser has them from STMicro for $0.37. Thats cheaper than a cup of coffee!
So, when you want to have a stash of opamps for prototyping, these are your best bet. I especially like just having the duals and quads around, and then swapping out a better specified opamp later on in the project if it’s called for.
The offset voltage usually isn’t so horrid, of course, although I still suggets coupling AC if you’re cascading gain stages.
Congratulations, TL082, you are the Chip of the Week!
- In one week (or so) I’ll be speaking @ SXSW-i as part of a panel on consumers, contributors and DIY culture w/fabulous Phillip T. & Natalie Z.
- In two weeks I’ll be holding 1/2 of a workshop on Hardware and Software Tools for Interactive Installations and Performance @ EYEBEAM with exceptionally talented Mark Coniglia (not to be confused with Caligula) of Troika Ranch. You can sign up starting on the 7th. We’ll be building MIDIsense boards and integrating them with Isadora. Wow! I expect it will sell out quickly so delay-not.
If you have the opportunity to see their current show on tour, [R]Evolutions, I highly suggest it: sort of like an abstract ‘qatsi but less Glass and more minimal/industrial.
A nice fellow came by the lab today and gave me his business card.
When I asked what the grid of holes were about, he replied “that’s the prototyping area.”
How f’ing hardcore is that?
He was also wearing a binary LED watch he built, cast in a chunk of solid acrylic, with capacitive touch sensors for the UI.
Thanks to the internet, I have found visual proof of this device (ripped from www.chicagoreader.com/pdf/050722/050722_ot_srilanka.pdf)
I hereby resolve to put more magic crystals and rainbows in my projects. Thanks, Todd!