Final Prototype Design
Prototype Case Design
Click the picture for an enlarged view of the final circuit schematic.
- This circuit consists of two amplifier stages with the output of the second stage acting as the signal input of the LM3914 LED driver.
- The amplifier chip consists of one LM324 chip, which contains four amplifiers. In this case, we are only using two out of these four. This differs from our initial amplifier selection; we chose the LM324 due to the fact that it consumes a miniscule amount of power, and is also known as a good amplifier for audio signals.
- Potentiometers were used in prototyping as to control the gain in the second amplifier stage. It is assumed that a final manufactured product will allow for control of gain during top-level use.
- There are two voltage sources: +9V and -9V. These are two standard 9V batteries with a common ground. Although the initial plan was to use one 9V battery, using a plus/minus voltage configuration increased hydrophone sensitivity by a large factor.
- Although there are no explicit filters in this circuit, the inherent frequency response has been measured in a lab with a function generator and oscilloscope. The approximate frequency range is ~300Hz to ~50kHz. This is well within the desired response range of leaks, which start at ~1kHz and trail off at higher frequencies.
Due to time limitations in the prototyping stage, there is no PCB layout for the final circuit schematic. Our deliverable prototype circuit is currently on a proto-board due to the amount of changes made to the circuit during functionality testing.