February 22, 2010 2 Comments

By Popular Request, You Can Support Jazari

Who am I to argue with the people? And rest assured, your donations will not fund the extravagant roboticist lifestyle we’ve seen depicted in Popular Mechanics in recent years. No Lear jets, no strippers, no coke-snorting automata. Every cent will help build (physical) drum machines and a bass machine. Oh yes, there will be a bass machine.

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February 22, 2010 4 Comments

Circuits, Solenoids, Microtiming

I’ve had some requests for a diagram of the circuit that I use, and I’m going to post it with the proviso that no one should actually imitate this design. Partly due to my own ignorance at the time, and partly due to a failed attempt to isolate the power electronics from the Arduino, I used a combination of an opto-coupler and an NPN transistor where a single PNP transistor could have been used. But for the curious, here it is:
When I have nothing else to do, which will be approximately never, I’ll rebuild the circuits with PNPs and eliminate the opto-couplers, which I suspect damage the switching speed of the PWM signal. I don’t have a scope to verify my hunch, but it would make sense; optos are used in compressors because they smooth out a signal, which is the opposite of what I want. Right now, everything works, so this is a lower priority. (more…)

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