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Doc Orion
#81
May10-11, 04:15 AM
P: 30
The finished circuit board for the screwdriver is roughly 6" x 1/2" -- this is just a hand wired piece of perf board where all the miniature components are either soldered directly to each other or connected by a few pieces of 24 gauge or thinner hook-up wire. Somebody more experienced in electronics could probably reduce that size down quite a bit further by using a printed circuit board with surface mount parts, but I was just too lazy to do that kind of detailed work.

However, just to do experimental work in sonics, size doesn't really matter when it comes to parts. Any amplifier, speaker, or audio generator will work as well as the next. The only part whre size is critical is the transducer-- the sound head. That has to be built so as to put out
about 140 dB and still be no larger than say 3/4" in diameter. That's a custom piece of work that's immensely tricky to make as two piezo disks have to be bonded together where the
polarity of each face is opposing to that of the other then connected to a diaphragm The whole thing must then be placed in the retaining ring; a time-consuming and intricate little job. All the rest is just machine shop kind of stuff.

* * *

It's been over four or five years since I had finished the screwdriver-- a long time before YouTube came along, so there ar no photos. 'Was no need for any, and nobody believed the screwdriver could be made anyway. Most people still don't think it can actually be done, but
a little knowledge of sonics & acoustics... is what most people lack, heh heh. Well, it doesn't matter.

I may put a picture of the new circuit board up here in a week or two; if I have the time. It's not the same as the original as I couldn't quite find some of the original parts and I made a
change in the output transistors, replacing the flat 220-type power transistors for 5 watt
metal can transistors... mostly because they look cool. They probably won't give any more acoustical power then the original flat power transistors but it might be fun to see how well the design works.

'Doc