Archive for September, 2005
I built this to test some “color washing” ideas I had, but it didn’t turn out like a hoped. In my mad rush to get it done (or maybe it was the post 1am state of mind), I wired it up backward… I was shootin for common anode, that is each led shares a common voltage supply and is controlled via their ground connection… but what I built is common cathode. Each led shares a common ground connection and is controlled by the supply.
Why is that bad? Well… If you’re going to use digital logic to control things, the easiest way is with a MOSFET transistor … the cheap and common N-Channel mosfets deal with low-side or ground connection … so with all the leds sharing the same ground, I cannot controll them independently.
Popularity: 8% [?]
WELL … I just tried changing to another theme I found on the wordpress site … whats that, you say, it doesn’t look any different. well, thats because I changed it back.
It seems the default theme formats my pictures for me, but the add on theme does not, so they distort the browser and layout all to heck.
Once I figure out how the default theme does the voodoo that it does, maybe another theme is in the future.
Popularity: 12% [?]
These little jems are serial controlled (i2c) PWM generators, designed by Philips Semiconductor for the purpose of controlling leds. I received samples of both the 9531 and 9533, which contain two separate pwm generators, and either four or eight outputs.
Above is a 9531 mounted to a prototyping adapter so it would go into a breadboard. Original tests with the chips were very interesting. The onboard pwm generator is capable of a wide range of frequencies and a full 8-bit gamut of duty cycles (256 steps). I ended up not liking these chips for a couple of reasons…
The biggest drawback is the chips only contain 2 pwm generators … while this would be great for a dichromatic white lite (yellow + blue), it’s no good for trichromatic (red + blue + green) … so the development would require two chips, and additional logic in the program to figure out which chip controls which color. The programming isn’t that big of deal… but I’m lazy. The second drawback is I couldn’t find anywhere to buy these. I don’t have any venture capital, so I can’t buy them in lots of 1000 from a regional distributor, and the supply houses I normally buy from didn’t have them in stock at the time I was working with them… so they’re on the back burner for now.
Popularity: 10% [?]
This is my protopod. I think I built four or five of these, some came out better than others … point to point soldering of jumper wires isn’t the best approach, especially when they’re all overlapping and what-not
each of those leds is rated at 200mW, but I’m only driving them around 100mW because they need a fairly heavy pcb with good thick traces to sink the heat.
you can see that I’m not the worlds cleanest prototype builder … but heck, I don’t care as long as it works
here is protopod fully illuminated
Popularity: 10% [?]
the peltier module sandwiched between two 1/4″ thick plates of pure copper. The hot-side plate is liquid cooled by a pump and radiator setup
the ice is condensation from the air, collected over the course about about an hour and a half. The pelt was being supplied from the 5v rail of the PSU .. the computer in the background is the guinea pig, but I’m waiting on some more parts to arrive first
Popularity: 37% [?]