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. 🙂
“This one is inspired by my experiences with the band and the DJ-Set and…well…you know why =-). Anyway, for already quite a long time I am looking for a way to read out the BPM information from Torq (any DJ-Software) in order to trigger Ableton with that. The aim is to have those things running synchronyzed without my interaction.
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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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.
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