Sunday, October 20, 2013

Assembly and Next Steps

We are making our circuit based on the Instructables example by Qs ( ), however we plan to modify the design as follows:
-Use parts we've found such as from broken microphones and the electrical component kit donated by Brett Hull
-Use one LED instead of multiple
-Use two CR2032 batteries on each side of the head rather than two 9v battery sources (combined to form a 6v power source)
-Fit the design to a pair of glasses, or as an attachment added to glasses
-Add a variable resistor to allow sensitivity adjustment for each side of the head (eg: when walking on the right sidewalk you will be more concerned with sounds of cars from the left, and can switch the right side off to avoid distraction and save battery life)
We aim for battery life to last just under 10 hours rather than the 20 hours estimate given on Instructables. This is based on the average 9V battery having 500mAh ( ), while the CR2032's have on average 200mAh ( )
This is the materials list of the Instructables version of the circuit:

Electret microphone
LM358 - Op-amp (8-pin DIP)
2N4401 - NPN general transistor (other audio NPN-types)
10k resistor x 5
2.2k resistor x 1
470k resistor x 1 (Can also be 330k)
100-ohm resistor x 1
1uF capacitor x 1
0.1uF capacitor x 1
9-volt battery and connector x 1
Perf-board and mounting parts
And now we start to put this together!

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