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KwaiChang

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About KwaiChang

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    https://github.com/frapacrinko
  1. Here are some pictures. It is running off the supercap in the picures.
  2. Just received mine in the mail pretty stoked.
  3. No problem. The impedance problem shouldn't be too difficult. I also noticed that with your summing amplifiers it sums the voltages out of the PGAs which has a maximum output is 7.5V p-p. your opamps have a -5v to 5v(10p-p) rails so you risk railing the opamps pretty easily when summing the signals. I don't know if you have a specific output you want. So I would recommend either increasing the rails to probably -15v +15v for the opamps or averaging the summing amplifiers so you can still use the -5v +5v rails?
  4. Yup that sounds right. Also since its a technically a mixed signal maybe isolating the digital and analog parts may help? maxim has a pretty good mixed signal layout [here] . It may not be necessary because it is such a simple system. I don't know too much about mixed signal stuff so dont take my word for it.
  5. I looked at your layout and it looks like your traces for the radio are not 50 ohms but ~65. How I did this is using AWR tx-line calculator(its free) , its really helpful when dealing with trace impedances. When doing RF stuff you always need to be conscious of impedance. Also using an SMA connector will help because it is designed for 50ohm impedance the pins you have right now are probably also messing with your signal because the impedance is probably greater than 50ohms.
  6. @@dubnet @@bluehash Thank you for the welcome.
  7. Sounds like a fun project. Daisy chaining the PGA2311 would save you a ton of pins. I'm not good with audio so I may be sticking my foot in my mouth but reading the data sheet for the OPA2134 it says that the distortion goes up if the input impedance is above 2k so that might be a factor for you. Someone please correct me if I am wrong.
  8. Hey all, I've had a launchpad for a while now but was too busy to do any bigger projects with. Just played around here and there. Recently I have taken a liking to PCB layout and I am trying to pursue it further. Just trying to think of some projects. Going through this forum I have realized what an excellent resource it is and that is why I have finally chosen to join. I am very interested in wireless sensors and I am playing with the idea of laying out a board with a cc430. But I believe might be too large of a project for the amount of layout experience I have. I would love any feedback from you guys.
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