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Prototype       Final Printed Circuit Board


Transmitter Prototype

We chose the analog FM transmitter shown below to implement as our final design.

FM transmitter (88-108 MHz) #5

  • 1.4V supply voltage

  • 11 components: 2 transistors, no tunnel diode

  • Substituted 2N3904 npn transistors for the 2 transistors in the schematic

Figure 1.  Schematic of transmitter circuit

  • No antenna resulted in a clear transmission distance of about 10 feet with the breadboard prototype shown below

  • The circuit is powered by a 1.4V size 10 hearing aid battery.

  • Composed of basic resistors, capacitors, transistors, and an inductor

  • Components are inexpensive and readily available

  • Relatively simple to implement

Figure 2.  Prototype of the analog FM transmitter.


Final Printed Circuit Board (PCB)

  • Utilizes surface mount components

  • Height: 7.8 mm

  • Width : 11.6 mm

  • Small enough to easily fit within the ear

  • Calculations show approximately 35 hours of battery life with a 1.4V hearing aid battery

                    Figure 3.  Final PCB.                                Figure 4.  Microphone and PCB in an ear mold.


Team AudioVibe - University of Idaho 2004-2005

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