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June 27, 2011
about 3 years ago
9.6 V should be fine, and each board should draw considerably less than 100 mA. Do the boards run OK on USB power? If they do, and assuming your wall wart is working OK (did you double-check?), the question of correct polarity remains. Centre positive if I remember correctly, but check the data sheet (no offense, I just make that kind of mistakes all the time myself, unless I’m paranoid with the multimeter :-) ). If you can’t make any of them run on USB power, you should try the troubleshooting guide on MakerJam. There’s a step by step recipe with test files and other stuff. There is an application note for the chip recommending addition of RC networks to counteract static discharges if you connect it to external audio equipment. Though this may be a good precaution, I haven’t experienced any static-related problems in my own projects, including one permanent museum installation with long headphone leads which has survived for two years in a tough environment, and another semi-permanent gallery installation which has been running for several months.
Good luck with your work, and yes, please let me know how the Mega does it. Did you resolve the power issue? With enought external power, I don’t see why the players would not run. Did you make sure you have the latest version of the firmware? If not, download it and install it on each board according to the instructions on MakerJam. These little boards are very useful, but also a bit cranky unless you treat them exactly right, and how to do that is not always very well documented, or maybe even investigated. When hooking up two boards to the same power supply and sound system I also ran into problems with HF interference which I attributed to some ground loop. I don’t remember exactly how I got rid of it, but it involved trying different ground connection points betweenthe two boards.
I tried both your solution (in essence parallelling the RX inputs of the trigger boards and connecting them to the same TX port if I understand you correctly), which did not work for some reason. My next step was to try using NewSoftSerial transmitting from two different pins but this was also unsuccessful (anybody out there who’s got it working that way?). I ended up using two communicating Arduino Pro Mini boards with a master-slave relationship - enabling me to hook up one true serial port to each trigger board. But honestly I have absolutely no idea why either of my other attempts (parallel connection to the same TX port and two different NewSoftSerial ports, respectively) would not work. Any ideas anybody?
The answer to your second question depends on the input impedance of your monitors, but I have successfully driven two pairs of headphones with one trigger board, so I doubt that you will have any problems as long as your inputs are decently standard.
about 4 years ago
Can this be modulated by switching the supply voltage, or otherwise? At what rate?
about 4 years ago
Can I control this directly from a TTL serial port like the Arduino’s or do I need some sort of RS232 converter?
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