Contact Microphone
Here are Todays Amazing Contact Microphone Deals
 |
 25 TFT 1080P Car DVR Cam Recorder Camcorder Motion detect F900LHD $63.18 Time Remaining: 19d 13h 40m Buy It Now for only: $63.18 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 4h 46m Bid now | Add to watch list |
 Wireless WIFI Network IP Camera Webcam Pan Tilt Audio Night Vision Mobile Detect $54.99 Time Remaining: 4d 2h 6m Buy It Now for only: $54.99 Buy It Now | Add to watch list |
 Spy Pen Camera Video Recorder Surveillance DVR DV hidden Camcorder 1280960 TF $0.99 Time Remaining: 5h 25m Bid now | Add to watch list |
 Q See 8 Channel Security System with 500 GB Hard Drive and 8 High resolution Cam $474.88 Time Remaining: 12d 9h 51m Buy It Now for only: $474.88 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 5h 50m Bid now | Add to watch list |
 Invisible NANO Spy Earpiece Earphone Cheat on Exam $33.33 Time Remaining: 29d 2h 3m Buy It Now for only: $33.33 Buy It Now | Add to watch list |
 25Color LCD IR LED 270Car Vehicle DVR Camera Video Recorder Monitor Dashboard $0.01 Time Remaining: 6h 19m Bid now | Add to watch list |
 25TFT 120Angle 1080P Car DVR Cam Recorder Camcorder Motion detect F900LHD $54.80 Time Remaining: 5d 12h 51m Buy It Now for only: $54.80 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 6h 48m Bid now | Add to watch list |
 24g Mini GSM Two Way Audio Device Sim Card Spy Ear Bug $18.99 Time Remaining: 6d 22h 36m Buy It Now for only: $18.99 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 7h 47m Bid now | Add to watch list |
 Mini HD Clothes Hook Motion Detection Spy Camera Hidden Pinhole 128096030Fps W $17.99 Time Remaining: 12d 3h 45m Buy It Now for only: $17.99 Buy It Now | Add to watch list |
 Lighter Spy DVR Hidden Camera Cam Camcorder USB Mini DV $0.99 Time Remaining: 7h 52m Bid now | Add to watch list |
 Mini Spy Pen Camera Video Camcorder Cam Recorder DVR Hidden DVR HD USB Card New $15.99 Time Remaining: 9d 23h 5m Buy It Now for only: $15.99 Buy It Now | Add to watch list |
 Hot sale Dual Lens Vehicle DVR Car dashboard camera DVR Video recorder+G sensor $75.00 (1 Bid) Time Remaining: 8h 3m Bid now | Add to watch list |
 Spy Cam Pen Camera Hidden Recorder DVR 1280960 Ext 8GB $23.99 Time Remaining: 27d 15m Buy It Now for only: $23.99 Buy It Now | Add to watch list |
 Hot sale Dual Lens Vehicle DVR Car dashboard camera DVR Video recorder+G sensor $75.00 (1 Bid) Time Remaining: 8h 6m Bid now | Add to watch list |
 6 IR LED 24 TFT Color LCD Car DVR Camera HD Recorder Vehicle Night Audio Video $27.30 Time Remaining: 27d 8h 9m Buy It Now for only: $27.30 Buy It Now | Add to watch list |
 W Lighter DVR SPY Camera 720x460 Sound Activated Record $0.88 Time Remaining: 8h 42m Bid now | Add to watch list |
 4pcs xHigh Sensitivity CCTV Microphone for Security Camera free shipping $15.00 Time Remaining: 20d 20h 18m Buy It Now for only: $15.00 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 8h 48m Bid now | Add to watch list |
 25 Color LCD 2706 IR LED HD Car DVR Camera Recorder Audio Video Recorder CMOS $29.59 Time Remaining: 17d 1h 19m Buy It Now for only: $29.59 Buy It Now | Add to watch list |
 Mini HD Vehicle 140 Wide Angle Car DVR Video Recorder Rotatable 2 LED Light $18.50 (14 Bids) Time Remaining: 9h 23m Bid now | Add to watch list |
 25 HD Color LCD IR 6 LED 270Car Vehicle DVR Camera Video Recorder Dashboard $30.59 Time Remaining: 21d 1h 20m Buy It Now for only: $30.59 Buy It Now | Add to watch list |
 6 IR LED DVR 270 25 Color LCD Car HD DVR Recorder Camera Night Audio Video $20.51 (4 Bids) Time Remaining: 9h 27m Bid now | Add to watch list |
 8GB Mini Spy Pen Camera Video Camcorder Cam Recorder DVR Hidden $27.25 Time Remaining: 16d 18h 8m Buy It Now for only: $27.25 Buy It Now | Add to watch list |
 VAUPT 80CDVR IR805H HD Car DVR 805H Direct $55.95 Time Remaining: 9h 30m Bid now | Add to watch list |
 HD720p IR Car Vehicle dash Camera Rotable 270 Monitor $27.29 Time Remaining: 13d 20h 44m Buy It Now for only: $27.29 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 9h 46m Bid now | Add to watch list |
 Car Camera HD 720P LCD Vehicle DVR Night Vision Cam Road Video Recorder H190 $51.78 Time Remaining: 6d 14h 25m Buy It Now for only: $51.78 Buy It Now | Add to watch list |
 New 20 TFT HD Dual Camera Car DVR Two Scene Vehicle Accident Dash Recorder D80 $49.99 (1 Bid) Time Remaining: 10h 9m Bid now | Add to watch list |
 Wansview Wireless IP Camera Audio PT 270120 Free DDNS iPhone Android View $52.99 Time Remaining: 13d 18h 53m Buy It Now for only: $52.99 Buy It Now | Add to watch list |
 4GB Mini DV+AC charger Camcorder Spy Video Camera Recorder DVR+webcam MD80 $6.79 (1 Bid) Time Remaining: 10h 11m Bid now | Add to watch list |
 Real HD 1080p Car Dashboard Camera Cam Accident DVR $68.99 Time Remaining: 8d 6h 31m Buy It Now for only: $68.99 Buy It Now | Add to watch list |
 HD 1080P Vehicle DVR Car Cam Camera Dashboard H264 HDMI Video Recorder F1000 $65.96 Time Remaining: 10h 36m Bid now | Add to watch list |
 8GB Fake Smoke Detector model SPY Hidden Camera Dvr DV with Remote Control NEW $42.49 Time Remaining: 23d 3h 5m Buy It Now for only: $42.49 Buy It Now | Add to watch list |
 Mini DV Lighter Spy DVR Hidden Camera Cam Camcorder USB New $5.99 Time Remaining: 10h 38m Bid now | Add to watch list |
 NEW GEN WIRELESS WEBCAM IP CAMERA AUDIO VIDEO WIFI CAMERA OSD IR Motion Detction $35.50 Time Remaining: 11d 20h 31m Buy It Now for only: $35.50 Buy It Now | Add to watch list |
 HD 1920x1080P Vehicle DVR Car Cam Camera Dashboard H264 Video Recorder F1000 $65.96 Time Remaining: 10h 41m Bid now | Add to watch list |
 Night vision Waterproof Outdoor Wifi Wireless WIFI IP Camera IR 24 LED M JPEG $68.39 Time Remaining: 23d 2h 45m Buy It Now for only: $68.39 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 10h 48m Bid now | Add to watch list |
 Logitech Alert 750i Indoor HD Security Master System $149.95 Time Remaining: 11d 19h 45m Buy It Now for only: $149.95 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 11h 47m Bid now | Add to watch list |
 MINI SPY BUTTON CAMERA Portable Pocket Recorder DVR $79.99 Time Remaining: 1d 1h 56m Buy It Now for only: $79.99 Buy It Now | Add to watch list |
 Y 4GB Mini Spy Cam Button Video Camera Recorder DVR G $0.84 Time Remaining: 11h 50m Bid now | Add to watch list |
 CCTV Security Camera Mini Microphone Mic Audio RCA DC output $4.99 Time Remaining: 4d 2h 28m Buy It Now for only: $4.99 Buy It Now | Add to watch list |
 25 LCD Road Dashboard IR Car Color Vehicle Camera Rotable Monitor Portable DVR $9.01 Time Remaining: 11h 56m Bid now | Add to watch list |
 Outdoor Security Camera Night Vision Infrared 36LED Audio CCTV Surveillance BU4 $29.98 Time Remaining: 22d 1h 26m Buy It Now for only: $29.98 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 12h 47m Bid now | Add to watch list |
 Fashion HD FULL 720P Glasses Spy Camcorder Hidden Camera 1280x96030Fps Gentle $47.89 Time Remaining: 12d 3h 54m Buy It Now for only: $47.89 Buy It Now | Add to watch list |
 spy Audio voice Bug Detector wireless Transmitter kit $55.00 Time Remaining: 12d 2h 11m Buy It Now for only: $55.00 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 13h 48m Bid now | Add to watch list |
 HD Spy Pen Camera Mini Video Recorder DVR 1280x960 8GB Ext $22.99 Time Remaining: 18h 36m Buy It Now for only: $22.99 Buy It Now | Add to watch list |
 25 Car 4 LED Vehicle Camera DVR recorder HD Wide $35.99 Time Remaining: 14h 22m Bid now | Add to watch list |
 Vehicle IR Car Dash Camera Road Recorder Dashboard C3 $27.59 Time Remaining: 26d 20h 18m Buy It Now for only: $27.59 Buy It Now | Add to watch list |
 4GB Mini Spy Pen Camera Video Camcorder Cam Recorder DVR Hidden DVR HD USB Card $18.88 Time Remaining: 14h 40m Buy It Now for only: $20.98 Buy It Now | Bid now | Add to watch list |
 1280 Camcorder CAR DVR Monitor Video Camera Recorder CCTV 25 LCD Night Vision $26.55 Time Remaining: 26d 19h 16m Buy It Now for only: $26.55 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 14h 46m Bid now | Add to watch list |
 Wireless WIFI IP Security Camera Webcam Night Vision 11 LED IR Dual Audio $52.75 Time Remaining: 24d 9h 37m Buy It Now for only: $52.75 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 15h 50m Bid now | Add to watch list |
 New 1 Pc Mini Microphone for CCTV Security camera RCA Output $4.50 Time Remaining: 22d 20m Buy It Now for only: $4.50 Buy It Now | Add to watch list |
 25 LCD Car Vehicle DVR 6 LED 270 Rotating Traffic Recorder $22.99 Time Remaining: 16h 12m Bid now | Add to watch list |
 Wireless System Surveillance Security CCTV 2 Camera 3PW $79.99 Time Remaining: 5d 17h 10m Buy It Now for only: $79.99 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 16h 50m Bid now | Add to watch list |
 Newest Mini Quad band GSM Two Way Auto Answer Dial Audio Sim Card Spy Ear Bug $22.07 Time Remaining: 18d 2h 31m Buy It Now for only: $22.07 Buy It Now | Add to watch list |
 20 TFT HD 8 IR Dual Two Camera Car DVR two Scene Vehicle Accident Recorder $29.99 Time Remaining: 17h 6m Bid now | Add to watch list |
 K2000 Full HD 1080P Car DVR 1240960 Dashboard Vehicle $49.69 Time Remaining: 6d 2h 47m Buy It Now for only: $49.69 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 17h 48m Bid now | Add to watch list |
 25 Car IR HD Night Vision Vehicle Video DVR 270 6 LED Recorder Camera $27.59 Time Remaining: 11d 3h 46m Buy It Now for only: $27.59 Buy It Now | Add to watch list |
 FULL HD car black box with GPS logger 19201080P 30fps HDMI CMOS GPS1000 H264 5 $149.00 Time Remaining: 17h 53m Bid now | Add to watch list |
 Waterproof Wrist Watch Hidden Recorder Camera DVR 4GB Cam $21.58 Time Remaining: 15d 1h 39m Buy It Now for only: $21.58 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 18h 47m Bid now | Add to watch list |
 Wanscam Wireless IP Camera Network Night Vision Mobile Detect 2 Way Audio P T $50.29 Time Remaining: 7d 11h 4m Buy It Now for only: $50.29 Buy It Now | Add to watch list |
 Brand New Mini Camera Action Sports Helmet Video Recorder DVR PB $14.51 (12 Bids) Time Remaining: 18h 48m Bid now | Add to watch list |
 2Way Audio Video Wireless Wifi 10 LED IP Camera Security Night Vision Network IR $50.99 Time Remaining: 28d 9h 13m Buy It Now for only: $50.99 Buy It Now | Add to watch list |
 25Color LCD IR LED 270Car Vehicle DVR Camera Video Recorder Monitor Dashboard $0.01 Time Remaining: 18h 50m Bid now | Add to watch list |
 9 x CCTV Microphone Mic for Security Camera Microphone $18.88 Time Remaining: 17d 12h 18m Buy It Now for only: $18.88 Buy It Now | Add to watch list |
 4GB 1080P Waterproof Nightvision Motion Detection Spy Hidden Watch Camera sc351 $9.99 Time Remaining: 19h 20m Bid now | Add to watch list |
 NEW GEN WIRELESS WEBCAM IP CAMERA AUDIO VIDEO WIFI CAMERA OSD IR Motion Detction $36.80 Time Remaining: 11h 11m Buy It Now for only: $36.80 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 19h 47m Bid now | Add to watch list |
 0850 Wireless Motion Activated Security Camera 24 Ghz $39.97 Time Remaining: 4d 8h 13m Buy It Now for only: $39.97 Buy It Now | Add to watch list |
 New Spy Sunglasses Hidden Convert Ski Camera Video Glasses Recorder mini DV DVR $0.99 Time Remaining: 20h 2m Bid now | Add to watch list |
 Nanny Wireless Mini Security Hidden Pinhole Camera Receiver Full Kit $26.99 Time Remaining: 27d 23h 38m Buy It Now for only: $26.99 Buy It Now | Add to watch list |
 Mini DV DVR Spy Sun glasses Camera Audio Video Recorder Y $0.84 Time Remaining: 20h 16m Bid now | Add to watch list |
 25Color LCD 2706 IR LED HD Car DVR Camera Recorder Audio Video Recorder $27.39 Time Remaining: 10d 4h 57m Buy It Now for only: $27.39 Buy It Now | Add to watch list |
 24g GSM BUG BUGGING DEVICE SPY EAR LISTENING AUDIO HIDDEN SECRET COVERT SIM CARD $8.00 (5 Bids) Time Remaining: 20h 43m Bid now | Add to watch list |
 4GB HD SPY PEN MINI DVR VIDEO CAMERA RECORDER AUDIO VIDEO 1280x960 EXT 8GB USA $23.95 Time Remaining: 29d 22h 23m Buy It Now for only: $23.95 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 20h 48m Bid now | Add to watch list |
 Wansview 1 NCB 541W + 1 NCB 543W Wireless IP Camera Free DDNS Mobile View WiFi $128.28 Time Remaining: 18d 17h 32m Buy It Now for only: $128.28 Buy It Now | Add to watch list |
 New HD Waterproof Sporty Watch with Mini Hidden Camera 4Gb DVR Black $22.27 Time Remaining: 21h 17m Bid now | Add to watch list |
 Full HD 1080P Car DVR Cam Recorder Camcorder Vehicle Dashboard Camera K2000 $52.98 Time Remaining: 25d 23h 45m Buy It Now for only: $52.98 Buy It Now | Add to watch list |
 Y Lighter DVR SPY Cam Camera 720x480 Sound Activate Recorder $0.84 Time Remaining: 21h 32m Bid now | Add to watch list |
 Motion Detection 1080P hd Waterproof spy camera watch IR Night vision 16GB $79.18 Time Remaining: 21d 10h 12m Buy It Now for only: $79.18 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 21h 54m Bid now | Add to watch list |
 Smoke Detector Alarm SPY Home security hidden camera DVR Motion Surveillance $44.99 Time Remaining: 22d 23h 50m Buy It Now for only: $44.99 Buy It Now | Add to watch list |
 4GB HD Spy Pen Camera Mini Video Recorder DVR Audio Video 1280x960 Ext8GB USA $24.99 Time Remaining: 22h 41m Bid now | Add to watch list |
 Night Vision Pan 355WiFi Wireless Wired IP Camera Record 2Way Audio Free DDNS $51.29 Time Remaining: 4d 17h 23m Buy It Now for only: $51.29 Buy It Now | Add to watch list |
 HD720P 25 LCD Car DVR Vehicle Camera Video Recorder $0.95 Time Remaining: 22h 46m Bid now | Add to watch list |
 Mini DV HD Clothes Hook DVR Motion Detection Spy Hidden Camera 1280x96030FPS $17.65 Time Remaining: 11d 50m Buy It Now for only: $17.65 Buy It Now | Add to watch list |
More Great Information on Contact Microphone:
Hermetically sealed condenser microphone by Rebecca
Hermetically sealed condenser microphone including an outer sealing diaphragm hermetically sealing an electroacoustic transducer within a case from the outside environment. The sealing diaphragm passes sound undiminished through an underlying intervening air space to a second active diaphragm of the electroacoustic transducer.
Specifically, the case has a hollow interior, a sealed end and an open end. The electroacoustic transducer is disposed within the hollow interior of the case, and the sealing diaphragm disposed over the top of the open end of the case such that the hollow interior of the case is completely sealed. An acoustic signal first impinges upon the sealing diaphragm causing deflections therein which in turn recreate the acoustic signal undiminished in the air space within the case between the sealing diaphragm and the active diaphragm.
The recreated acoustic signal then impinges on the active diaphragm of the electroacoustic transducer causing deflections therein that are converted to an electrical signal outputable from the microphone. Thus, the sealing diaphragm prevents water vapor and other contaminants from coming into contact with the internal components of the microphone, while still allowing the acoustic signal to reach the active diaphragm.
Condenser microphones are widely used to convert acoustic signals to proportionate electrical signals, such as is necessary in electronic voice communication applications. These conventional microphones typically include a capacitive transducer made in such a manner that one electrode of a capacitor structure is formed by an electrically conductive diaphragm. This diaphragm is disposed adjacent to, but insulated from, a stationary electrode forming the second electrode of the capacitor structure. The two electrodes are spaced apart with an air gap in-between. A relatively high DC bias voltage is applied between the electrodes. Variations in the electrode spacing caused by deflections of the diaphragm in response to the force of acoustic wave energy incident on the diaphragm, produce a change in capacitance. A detection network is connected to the capacitive transducer such that the change in capacitance is detected and transformed into an electrical signal proportional to the force of the acoustic wave energy applied to the diaphragm.
Conventional condenser microphones have not been completely sealed from the atmosphere in the past because they would become inoperative in the face of variations in barometric pressure or altitude. For instance, an increase in the atmospheric pressure outside the diaphragm would tend to deflect it towards the stationary planar electrode of the transducer, thus introducing an error in the electrical signal output from the device and reducing the device's sensitivity to actual acoustic inputs. To alleviate this problem, traditional condenser microphones included a vent or pressure relief hole in the diaphragm, which allowed air to flow between the region outside and inside of the diaphragm to equalize the pressure and prevent the aforementioned unwanted deflection.
Although the diaphragm vent hole prevented changes in external pressure from affecting the performance of the microphone, it also introduced some undesirable side effects. For instance, water vapor can be introduced into the air space between the diaphragm and the stationary electrode when air having a high relative humidity is drawn onto this space to equalize an increase in the external air pressure. This water vapor can have deteriorative effects on the transducer components. Similarly, if the microphone was submersed in water, the vent hole would allow water into the space inside the diaphragm, thereby damaging or making the transducer inoperative. In addition, the vent hole allows contaminants, such as dust, to enter the space under the diaphragm. This could cause electrical noise if the contaminants come into contact with the sensitive stationary electrode of the transducer, or possibly with the electronics of the detector circuit. The contaminants might also clog the vent hole and cause the same problems described previously in connection with the need for a equalization port in the diaphragm.
The only heretofore known microphone that has been sealed from its outside environment are those employing a diaphragm with a high mechanical impedance. A hydrophone is an example of this type of microphone. These microphones have a bladder connected to the space behind the diaphragm which expands and contracts to equalize the aforementioned internal/external pressure difference. However, a condenser microphone requires a diaphragm having a much lower mechanical impedance. A bladder consistent with the size of a condenser microphone would not be able to absorb all the air displacement necessary to equalize the inside pressure to that of the ambient environment.
Therefore, what is needed is a condenser microphone which is completely sealed from the environment external to the diaphragm of the transducer, and still capable of operating efficiently in the face of changing ambient pressures.
Ningbo Tongxin Microphones offers the best variety of quality Condenser Microphone for Studio, Podcast, USB, Instrumen, Conference, Broadcast and Field Recording.
Article Source: http://www.earticlesonline.com/Article/Hermetically-sealed-condenser-microphone/853541
Tags: contact, contact microphone, contact microphone diy, contact microphone piezo, contact microphone stethoscope, contact microphone uses, diy, microphone, piezo, sound