A Real Sonic Screwdriver?

mintigo

That sounds real cool. Hey Doc... I've sent you a PM, please respond as soon as you can, thanks! :D

Doc Orion

I just got the new Doctor Who DVDs and saw the Doctor's brand new sonic screwdriver. It does just about everything but make coffee-- or I suppose because they're British, it does everything but make tea.

There's a book, Father Time, where the 8th Doctor who's stranded on earth and with no memory of his origins, has made a sonic suitcase; '80s tecnology in action... I suppose you could probably get a coffee maker in that. :-)

'Doc

Vesane Vates

Quote by Doc Orion

Hi;

I had built a working sonic screwdriver once, a few years back.
...
At a certain frequency the screws on the box began to turn fast and easily until they reached the bottom; at a higher frequency they slowly unscrewed themselves...

Can someone please try this one again and get video? If Doc said he got it working, then at least there's hope that it's not purely theoretical...

by the way just thought I should add an article about it: http://www.smh.com.au/world/science/...205-18lfb.html

Doc Orion

I don't have the things to do it any more; time has passed on. However, if anyone else wants to do it or is equiped, here's the things that you must have to repeat those early experiments:

1. A piezo speaker box with screws at the back.

I used to get those from Radio Shack. Years ago they were cheap and readily available. I'd buy them and gut them for the piezo speaker element inside, then usually throw away the box except for one I kept for experimenting.

If you can find a similar box, good. But sound waves won't turn wood screws (a real screwdriver has trouble turning wood screws) so you need screws that wil turn easily;
say those on the back of some old woofers, etc.

2. A variable frequency audio sound source.

It should be capable of runing from 0 Hz up to at
least 15 kHz. And preferably, it should be nice clean sine waves; you can use a squarewave
source like a 555 oscillator but because it produces harmonics, things may not go too well.

I used a simple XR2206 circuit in sine wave mode, but I suppose any good electronics or
acoustics lab should have an audio frequency/ function generator sitting around or a kit might be available from some of these electronics places that sell educational kits.

3. A good amplifier connected to a step-up transformer.

The output from the audio generator gets amplified; it's voltage stepped up by the transformer-- 8ohm : 1K is a standard transformer and easy enough to find. Or at least it used to be back in those hobby friendly days. Check Mouser or other suppliers.

4. A piezo buzzer

A piezo buzzer is not a very good speaker, but it will work pretty well in this case because the step-up xformer will make it extremely LOUD. At the resonance frequency of the buzzer,
it can get as loud as 140 to 143 dB some 2" from the buzzer. Also, since there is a small
hole in the buzzer, the sound is somewhat concentrated.

BUT... you can do without the xformer and piezo element if you connect the amplifier directly to a bigg woofer; say 8" or larger. Set the top of the piezo box directly on the speaker cone. Use the standard 8 ohm speaker. Connect it to the amplifier with standard speaker wire or
a shielded cable with an audio plug on one end and a pair of aligator clips on the other.

NOTE: if you use the woofer method, the screws will turn themselves downward but not
upwards. That is, turn the screws up to their stops and the sound at the right resonant frequency will make them turn downwards until they can't go any further. But because this
is considerably more inefficient than using the piezo speaker, a woofer can't produce enough vibration at the "anti-resonance" frequency to make the screws turn upward against the pull of gravity-- for that you need sound at very great intensities and only a piezo speaker can produce sound that loud.

And, Oh, use ear protectors: sound that loud can hurt the ears and give you one hell of a headache.

Here's a lesson from "Acoustics 101:" the resonant frequency of an object depends upon such factors as its size and mass. This is why the resonat frequency of a wine glass is much higher than that of a bridge. A good example is to take a crystal goblet (a wine glass will do but it will be trickier) and feed the sound from the loud speaker and adjust the frequency upwards until resonance; at that point, the goblet will shatter violently. Only sine waves can be used for that experiment.

Good luck-- :-)

'Doc

Vesane Vates

Quote by Doc Orion

I don't have the things to do it any more; time has passed on. However, if anyone else wants to do it or is equipped, here's the things that you must have to repeat those early experiments:

1. A piezo speaker box with screws at the back.
...
2. A variable frequency audio sound source.
...
3. A good amplifier connected to a step-up transformer.
...
4. A piezo buzzer
...
NOTE: if you use the woofer method, the screws will turn themselves downward but not
upwards.
...
And, Oh, use ear protectors: sound that loud can hurt the ears and give you one hell of a headache.
...
Good luck-- :-)

'Doc

Thank you so much! With a list that clear, I really have no excuse not to try building one! (Other than... having no experience in building stuff... but I'll get there

)
If I ever get one working I'll be sure to post pics and vids here.

Thanks again very much for replying, Doc; you're a legend!

Doc Orion

Me? Nah... I could never get my screwdriver to work quite right; a problem with the switch. Check out the video of the screwdriver prop--

http://www.youtube.com/watch?v=UXGdS...eature=related

Now that guy's screwdriver is beautiful! Too bad the only thing it does is makes noise. But I guess it's sonic after all... <g>

'Doc

Vesane Vates

Quote by Doc Orion

...

Now that guy's screwdriver is beautiful! Too bad the only thing it does is makes noise. But I guess it's sonic after all...

'Doc

Pah, the aim is to get a *working* screwdriver; one that can remove or put in (probably mostly removing :P) screws using sound and not contact.
Even if yours didn't look like the Doctor's (or perhaps *especially*, for creativity's sake) I'd want it waaaay more xD

Doc Orion

Okay...

I was going to keep this secret until 2022, but doing some much needed cleaning I stumbled across a binder with 95% of the working drawings for the Screwdriver. It's unfortunately missing two things: the drawings for the sound-head, and the bottom end cap/ frequency control knob.

Before anyone starts to salivate uncontrollably, let me make this point clear: I no longer have the original CAD files, and I have no way to transmit these files electronically. For some unexplained reason, every scanner I have ever bought has broken down and stopped working within three days after I buy them. My fax machine didn't last too much longer.

SO, if anyone really wants the working plans-- the circuit diagrams for both the
Doctor-screwdriver and the Romana-screwdriver as well as the machinist drawings for the main pasrts of the Screwdiver-- first, send me an email and I will give you my address. Then you can send me a 8" x 10" SASE and as soon as it warms up here, I'll go to Kinko's and have copies made of the plans. From there, children, you are on your own; this homeboy has too many other projects to juggle. ;-)

'Doc

Doc Orion

For those a ittle too lazy to do it physically, here's an idea: get a copy of the Cool Edit program. This does a lot of things with sound-- for example, it can be set to generate a sine wave of a given frequency and modulate it with another to get the sound the Doctor's Screwdriver makes or the sound european sirens make, whatever...

Cool Edit can be gotten for free-- so it's very cheap for those on a bdget. Get the program, learn to use it, and feed the signal from your sound card into an amplifier and a good hi-fidelity speaker. See what kind of amazing things ya can do. <g>

But being software, it doesn't have the versatility a real circuit has, yet it has potential. I should point out though, that the first couple versions of Cool Edit while free, doesn't
allow the use of all of the features at the same time but that's okay; most don't need
every feature at once anyway. ;-)

'Doc

Doc Orion

When I first started out I had a number of engineering directories which had some amazing items listed that weren't your usual consummer products. It's been a long time but they are still around, a 12 kHz piezo transducer that's not quite perfect for the Screwdriver, but very close to it.

http://parts.digikey.com/1/parts/485...-13da-12a.html

I chose 13 - 15 kHz for the Screwdriver's operating frequency because most people can't hear that high-- and I don't care what the books say: damn few people can hear up to 20 kHz. So some text books on sonics consider ultrasound starting at 13 kHz and it's a good compromise since acoustical power goes down as frequency goes up. You want to be able to use the Screwdriver at 4:00 in the morning and not wake the neighbors, so use lower ultrasound and even 12 kHz is on the edge of audibility for a lot of people.

Romana's screwdriver uses "pure" ultrasound so high, it's not even audible when working. The design is a lot simpler, but it gets harder and harder to find a transducer for say 18 kHz. There's a company called APC

http://www.americanpiezo.com/product...c_benders.html

who might make custom transducers for a small fortune, but some enterprising person could make them fairly easily from a few really thin 1/2" dia. peizo discs, a 5/8" dia. (or slightly larger) brass disk, and some electrically conductive glue to bond the piezo disk to the brass. Some experimenting with the thickness of the brass would probably sooner or later get you a "bender" that will be resonant at 13 kHz then you really will have some acoustic power! That 12 kHz commercial transducer's problem is that it's kinda small at
1/2" around-- the sound head should be at least 5/8" dia to 3/4" around; the larger the transducer, the more power it puts out.

Of course you can always use a cheap plastic piezo buzzer from Radio Shack, but it won't look that good heh heh. ;-)

'Doc

Wildep

Quote by Doc Orion

I don't have the things to do it any more; time has passed on. However, if anyone else wants to do it or is equiped, here's the things that you must have to repeat those early experiments:

1. A piezo speaker box with screws at the back.

I used to get those from Radio Shack. Years ago they were cheap and readily available. I'd buy them and gut them for the piezo speaker element inside, then usually throw away the box except for one I kept for experimenting.

If you can find a similar box, good. But sound waves won't turn wood screws (a real screwdriver has trouble turning wood screws) so you need screws that wil turn easily;
say those on the back of some old woofers, etc.

2. A variable frequency audio sound source.

It should be capable of runing from 0 Hz up to at
least 15 kHz. And preferably, it should be nice clean sine waves; you can use a squarewave
source like a 555 oscillator but because it produces harmonics, things may not go too well.

I used a simple XR2206 circuit in sine wave mode, but I suppose any good electronics or
acoustics lab should have an audio frequency/ function generator sitting around or a kit might be available from some of these electronics places that sell educational kits.

3. A good amplifier connected to a step-up transformer.

The output from the audio generator gets amplified; it's voltage stepped up by the transformer-- 8ohm : 1K is a standard transformer and easy enough to find. Or at least it used to be back in those hobby friendly days. Check Mouser or other suppliers.

4. A piezo buzzer

A piezo buzzer is not a very good speaker, but it will work pretty well in this case because the step-up xformer will make it extremely LOUD. At the resonance frequency of the buzzer,
it can get as loud as 140 to 143 dB some 2" from the buzzer. Also, since there is a small
hole in the buzzer, the sound is somewhat concentrated.

Good luck-- :-)

'Doc

Could you please give me the sizes for all the components?
and are all of those components used for just the SS?

Wildep

Quote by Doc Orion

Hi;

I had built a working sonic screwdriver once, a few years back.

It’s common knowledge that sound/vibration can effect physical structure:soldiers must break step before crossing a bridge, an opera singer can break a wine glass by hitting the proper note, and a helicopter can easily shake a house from a distance overhead. So it seemed to me to be just a matter of frequency and power.

To test the theory I used an old box from a disused piezo-speaker that had a pair of screws on its top as well as a standard stereo speaker. The speaker was connected to a medium-powered stereo amplifier that was being fed by a simple audio sine wave generator.

At a certain frequency the screws on the box began to turn fast and easily until they reached the bottom; at a higher frequency they slowly unscrewed themselves. This was resonance at work. Going one step farther, I placed the speaker up against a solid wood door and adjusted the frequency upward; at a certaain point the key in the door turned itself to the right although not with enough force to open the lock. The key could even be turned when the speaker was some distance from the door (basic Mechanical Engineering 101). At one point I even managed to get dinner plates to spin on the sound head. That was cool.

Once I knew the theory was right, I had to see if I could a practical screwdriver. I tried several ideas but what worked best was a standard piezo buzzer from Radio Shack. Driven at the right frequency and at high enough voltage, it could easily turn the screws on the ox from three to four inches. This was great but at 143 dB, this didn’t work too well for quiet breaking and entering at 3:00 in the morning; not to mention it hurt any bystanders. I decided that this had to work at a near ultrasonic frequency, say 13 kHz. This was a frquency most people could only barely hear. By itself, this frequency didn’t turn the screws too well (resonance effects end at 10 kHz) but when either frequency or amplitude modulated, that worked the same as being used at an audible frequency. It could still be heard, but only because of the secondary modulation—if set for 10 Hz, one would hear the 10 Hz beat and not the 13 kHz even though it was mouch louder.

The final problem to be solved was the size. The SS took a lot of power. One couldn’t use big batteries or carry a battery pack; tat was tacky. The solution came when some company produced a neat little IC that could easily boost 3 volts to 9 VDC. Instead of big batteries, I only needed two sub-C to get all the power the SS needed. When it was finished, the sonic screwdriver was about 11 inches long; a little shorter than the 5th Doctor’s screwdriver (I had a chance to ask Peter Davidson about it once). Made out of aluminum and copper, it was a thing of beauty. Its only design flaw was the on/off switch: I could never get that like on TV. :-)

Eventually, somehow, it got lost...

‘Doc

Didn't you take pictures of the SS when you had it? or a video? if you did I'm sure everyone here would like to see.

Doc Orion

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

zzzspawn

Oh my! :OO :FF

I just stumbled upon this tread randomly from google! and as I've been a member of physicsforums for some time now, I don't believe I've ever sat down and read one as thoroughly as this one! it's simply fascinating! I'm going to build one of these within the next year for sure! :D

Doc, you are amazing! :D love the hard work! ^_^ and same to everyone else! =)

ajs84

Hey Doc is it possible to get a schematic of the circuit board and a parts list with all the sound ranges that needed be needed for your Sonic Screwdriver. Or as I like to call it a Frictionless Screwdriver.

Doc Orion

Quote by zzzspawn

Oh my! :OO :FF

I just stumbled upon this tread randomly from google! and as I've been a member of physicsforums for some time now, I don't believe I've ever sat down and read one as thoroughly as this one! it's simply fascinating! I'm going to build one of these within the next year for sure! :D

Doc, you are amazing! :D love the hard work! ^_^ and same to everyone else! =)

I have to say that while it's the best I can do, it is a bit crude. But unless one has access to Time Lord technology, it's hard to get sophisticated ciruitry to fit into a sleder tube.

Since the orignial device, it has occurred to me that I could probably get more acoustical power from a better transformer. I used a standard Radio Shack xformer because 1) they're cheap and 2) they work okay. But if I had been a smarter fellow I would have made a special 'former that was round instead of square and with a higher turns ratio. The standard RS transformer was 1K: 8 ohms bcause you can get those anywhere-- at any Radio Shack or places like Mouser for a few bucks. I used to know the turns ratio but these days I've forgotten it, but I know it's not high.

A 'formr with say a 50:1 or even 100 :1 would put out a lot more voltage-- and more voltage means more power from the piezo ceramic. The only thing is that standard piezo discs are not made for very high voltages; maybe 60 volts max! Too much voltage and the ceramic cracks before you can blink an eye. But ya need more voltage to get more sound power. Might be a Catch-22 situation *but* some ceramic companies make high power ceramics such as PZT-8 that can take a higher voltage without cracking. Now here's the catch (and there's always a ctach): PZT-8 doesn't work as well as PZT-5A, the ceramic used in standard piezo beepers, speakers, etc on a volt-to-volt basis. But the PZT-8 can take higher voltages so it kinda becomes a trade-off: you would need a lot more voltage to get the amount of power gotten from driving PZT-5A, but 5A will crack when driven from excessive voltages. Still, it *is* more power, but it might make the Screwdrivr a litle bit bigger using a round transformer.

Something to think about. ;-)

'Doc

Doc Orion

Quote by ajs84

Hey Doc is it possible to get a schematic of the circuit board and a parts list with all the sound ranges that needed be needed for your Sonic Screwdriver. Or as I like to call it a Frictionless Screwdriver.

I was lucky: by accident, I found the hard copy for most of my Screwdriver files. I even offered to copy them for a few folks-- all I asked for was a SASE (self-addressed stamped envelope), but what I got was people who wasted my time. As Scotty once said, "Fool me once, shame on you. Fool me, shame on me."

Short answer, these days I don't offer to make copies any more. 'Sorry.

'Doc

Similar discussions for: A Real Sonic Screwdriver?
Thread	Forum	Replies
Survives Screwdriver Through Skull	General Discussion	2
Sonic reflexes	Biology	4
Help on sonic boom	Mechanical Engineering	12
Sonic flow	Engineering Systems & Design	12

mintigo	A Real Sonic Screwdriver? That sounds real cool. Hey Doc... I've sent you a PM, please respond as soon as you can, thanks! :D

Doc Orion	Me? Nah... I could never get my screwdriver to work quite right; a problem with the switch. Check out the video of the screwdriver prop-- http://www.youtube.com/watch?v=UXGdS...eature=related Now that guy's screwdriver is beautiful! Too bad the only thing it does is makes noise. But I guess it's sonic after all... <g> 'Doc

zzzspawn	Oh my! :OO :FF I just stumbled upon this tread randomly from google! and as I've been a member of physicsforums for some time now, I don't believe I've ever sat down and read one as thoroughly as this one! it's simply fascinating! I'm going to build one of these within the next year for sure! :D Doc, you are amazing! :D love the hard work! ^_^ and same to everyone else! =)

ajs84	Hey Doc is it possible to get a schematic of the circuit board and a parts list with all the sound ranges that needed be needed for your Sonic Screwdriver. Or as I like to call it a Frictionless Screwdriver.