Laser Microphone: Difference between revisions
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==Random Thoughts== | ==Random Thoughts== | ||
* bandpass filters to block out all but voice range. | * bandpass filters to block out all but voice range. | ||
** Possibly adjustable in case someone's voice is deeper/higher | ** Possibly adjustable in case someone's voice is deeper/higher | ||
** The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz | ** The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz | ||
* http://www.youtube.com/watch?v=RR5tPfYWnls | |||
** This guy actually build an IR transmitter/receiver but it is still modulated light. He uses a carrier frequency to get rid of background noise caused by ambient light. This sounds like a fantastic idea. | |||
==Notch Filter== | ==Notch Filter== | ||
| Line 9: | Line 10: | ||
** Has schematics specifically for 60hz hum | ** Has schematics specifically for 60hz hum | ||
** Might also be an amplifier | ** Might also be an amplifier | ||
** '''UPDATE 6/28/10''' | |||
*** Haven't been able to get this circuit working yet. However, I built this other circuit (Page 41 of the link) with Todd and it worked perfectly. According to the graph on page 42, it might notch out higher frequencies too that I actually don't want to notch out. Will have to test for this by experimenting with the laser mic. The circuit on page 42 has a better looking graph so I might be able to try that circuit too if the other one filters too much. | |||
*** http://books.google.com/books?id=-sE7JVywygQC&pg=PA41&lpg=PA41&dq=forrest+mims+60hz+hum+filter&source=bl&ots=pj3Lsh4Nq7&sig=eYwDeNs09xLpLoYo4r7fh_UpVtw&hl=en&ei=xNAoTLL2GcX_lgfDt8mECA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBYQ6AEwAA#v=onepage&q&f=false | |||
==Audio Amplifier== | |||
* http://www.techlib.com/electronics/audioamps.html#LM386 | |||
** Has several different schematics for amplifiers. | |||
Latest revision as of 20:29, 30 March 2024
Random Thoughts
- bandpass filters to block out all but voice range.
- Possibly adjustable in case someone's voice is deeper/higher
- The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz
- http://www.youtube.com/watch?v=RR5tPfYWnls
- This guy actually build an IR transmitter/receiver but it is still modulated light. He uses a carrier frequency to get rid of background noise caused by ambient light. This sounds like a fantastic idea.
Notch Filter
- http://www.members.shaw.ca/roma/nine.html
- Has schematics specifically for 60hz hum
- Might also be an amplifier
- UPDATE 6/28/10
- Haven't been able to get this circuit working yet. However, I built this other circuit (Page 41 of the link) with Todd and it worked perfectly. According to the graph on page 42, it might notch out higher frequencies too that I actually don't want to notch out. Will have to test for this by experimenting with the laser mic. The circuit on page 42 has a better looking graph so I might be able to try that circuit too if the other one filters too much.
- http://books.google.com/books?id=-sE7JVywygQC&pg=PA41&lpg=PA41&dq=forrest+mims+60hz+hum+filter&source=bl&ots=pj3Lsh4Nq7&sig=eYwDeNs09xLpLoYo4r7fh_UpVtw&hl=en&ei=xNAoTLL2GcX_lgfDt8mECA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBYQ6AEwAA#v=onepage&q&f=false
Audio Amplifier
- http://www.techlib.com/electronics/audioamps.html#LM386
- Has several different schematics for amplifiers.