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Doktor Andy is back to his crazy designs! When you can’t easily hack out a signal from a controller why not make a circuit that “looks” at it for you. That is exactly what the Ghetto BPM Detection does. I had the DJM800 from Pioneer lying around here for a few days (yes…the one with the MIDI-Clock output) but it wasn’t that good since the BPM detection is a little dull and inaccurate. Furthermore it is a little too expensive.”
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November 13th, 2007
The two resistor values should be swapped: the 100 Ohm value is too low and the 1K one is too high. That means the current flowing through the phototransistor would be close to 50 mA ((Vcc-junction drop)/R), which is also too much to drive a bc107 base, and would also make the two transistors darlington part useless. That is, if the phototransistor was able alone to sink 50 mA, the darlington sinking 5mA would add nothing and could be eliminated.
I’d use values from 1 to 10 KOhm for the phototransistor resistor and a lower value for the second one; they probably got swapped during the circuit drawing.
November 13th, 2007
[...] post by Alan Parekh Written by admin on November 13th, 2007 with no comments. Read more articles on [...]