Introduction: Edit 1/18/2016
this project hit a road block.....I'm waiting on Amazon Prime to deliver some component's and found some interesting sources for components that I thought other "makers / tinkerer's might find useful...
1)... burnt out CFL bulbs (be careful of the mercury and phosphorous in the bulbs themselves) if you open the base it is crammed full of coils and capacitors all with very useful values.
2).... very small LED's....if you go to Amazon or Digikey the LED's can be reasonably priced, but the delivery time and shipping can be a bear (or other B word)..
I was searching for "very small (3 mm or less)" LED's and found they were either not available or required shipping from Hong Kong....a source I never considered....Big Lot's, back in the gardening / ornamental lights section they sell strings of "20 LED underwater lights" (actually 2 strings of 20 in the box including 2 battery cases) for around $8.....that works out to $.20 per bulb (but factor in the 2 battery holders and flasher circuits and it's a wealth of hack-able parts). the bulbs are amazingly small, literally a .5 mm droplet suspended between the 2 wires
the lights from the UW strings are fairly robust, and once the wires are stripped of their insulating coating (lacquer) it takes solder well....and they are amazingly bright even with current reducing resistors.
Step 1: Wearable Tech, Sound Triggered LED.
I got the idea for this after spending an evening at a dance club ....a little too close to the speakers (we've all been there)..
I see all of these wearable lights Instructables but they all have the same annoying line "using an Arduino"...Maybe I'm a chronic late adopter but it seems like a whole lot of tech for the simplest projects (my God, $20 of tech to flash an LED....Guys!.. a 3909 LED flasher chip runs about $2 if you can find it on line).
the effect I was looking for is a light that flashes with loud noises (thumpin beat y'all). the prototype here will be worn over the ear. Later versions could be a lapel pin, a broach, a belt buckle....suggestions would be appreciated.
Also....if you can help with a better circuit it would be appreciated, fine tuning the frequency range (this version works with any loud sound)
1)...two 2N-2222 switching transistors
2)... two resistors 15 K ohms* and 6 K ohms*
3)... an Electret microphone (capacitive not peizo)
4)... an LED
* the resistors were determined by trial and error (using variable resistors in the range of the original schematic until I found the best match for the application, then measuring the settings on the "pot" with a VOM meter).
I built a prototype and adjusted the schematic I found on line (Google Images search under "sound activated LED".no need for the 100 MFD capacitor, though in later versions I may add a capacitor to set the frequency range)
I have tested the unit using an external power pack but still need to mount the button battery to the circuit board (see next step....
Step 2: Battery Mounted
functions as designed, but I'll need to hit the club tonight (dang it) to test it under the high noise enviroment...
I will try to produce a video showing it in operation (and chance annoying my neighbor with the loud music)....
a semi fail.....the sensitivity is too low....I put a variable resistor on the input side of the circuit but it didn't improve the sensitivity (is possible the microphone just isn't suited for this).....will have to test in a high noise situation...
the transistors were scavenged (as well as the microphone) but the design and things I learned from the experiment will help in the next version.
I added a couple of follow up pictures to illustrate the battery holder.
I did test the unit and it wasn't bad, but someone (theICguy) posted a promising circuit using a 386 OP amp that may solve a world of problems.
I have found some amazing circuits on Pinterest and Instructables but needed components have to be shipped from Hong Kong (from Amazon......Digikey is good, but their shipping costs are too high for a small order).