still remember my DIY light saber which I made couple of weeks back?? http://shin-ajaran.blogspot.com/2010/03/diy-light-saber-with-15-and-60minutes.html
I brought it to BarCampSingapore5in SP, gave a flash talk on how to make it. the response was OK, there are some jedi out there in the crowd... One comment from the ground was.... where is the sound from the light saber. It suppose to have the VOOOOM sound every time the light saber is swing.
OK, Sim Lim Tower Here I come again!.........
there are 2 parts to solve this issue.
1. the mechanical motion detection switch
2. the voice/sound electronics.
item 1 was tricky to solve, because the COTS available is out of my reach. I tried to fabricate one with ball bearings and some metal plate, a close circuit will form when the metal ball bearing touch the metal plate. The outcome is not satisfying. I am using a roller switch instead.
item 2, i bought a "puma" voice digital kit for $8 at SLT, so that I can quickly hook it up to my light saber.
Sadly, on the first try, nothing worked!!!!
The troubleshooting begins~!~!
The transistor is configured as a BJT and act as an amplifier in the circuit, and the IC is the one that generates the sound. The kit's PCB (printed circuit board) and the IC chip does not contact properly, there is some miss alignment. Small issue I presume and I ignore it.
the voltage between base and emitter suppose to be 0.7v when it is in forward biasing, eg the transistor is working. But, i got a 0v reading on my multimeter. The best part, voltage between collector and emitter is 2.7v which is the voltage of my supply. it means that emitter and collector is shorted, e.g spoilt transistor.
All the other components tested fine, except for the chip alignment... small issue....I think....
Can't really sit down to trouble shoot, because in between office hours, I have to attend meeting and conference and the circuit is left at a corner paralyzed.......
When I got the time to fix it, Thinking that is the transistor fault, I swapped it with another spare I have. But I do not have the exact c9013 low power and have to used another NPN equivalent make the chip contact to the PCB closer with the use of the piece of paper as spacer. When I decide to cut the PCB to make sure the alignment is accurate and solder the chip's contact and the PCB contact
this is what i got... random noise.....
Is it the chip is spoilt, or the transistor i swapped is not working. The only good news, voltage between emitter and collector is not 2.7v and voltage between base and collector is 0.5v.
I deduce that, it should be the transistor, so I changed back to the default one and voila~!
I got my "PUMA" roar. but.......it doesn't sound like a puma, more like a creepy animal you watch on horror movie...
The whole idea of using a swappable chip is such that when i get my paws on the VOOOM sound chip, I can easily hook up to my circuit. Since now I solder down already to make the circuit more realiable, this is not any option. Nonetheless, I "wire wrap" it to my light saber.