A Real Sonic Screwdriver?

dr dodge

or put the screws in on both sides of the wall at the same time

dr

Doc Orion

Ahhh... I see. You want the kind of sonic screwdriver that the faux 11th Doctor had: handle made of wood, has a shaped metal piece for turning screws, and is sonic when you bang it against a wall heh heh.

The Chemist

nice, that makes sense. and hey, its the closest thing we have so far. any idea where i can get some of this stuff? future shop? radio shack? ebay?

Lancelot59

Digikey would be a good place to start.

Doc Orion

Best place is Mouser; you can get everything there except for the transducer-- that may be pretty hard to come by these days; the ceramics companies aren't as nice as they used to be to the experimenter. Ebay? Hmmm....

Just a reminder: smallness is the goal. Unless you are really skilled at working with surface mount parts, stick to 1/8 watt resistors and 16v tantalum caps. With creative wiring, it's amazing how compact you can get those circuits.

'Doc

Doc Orion

Back in the day-- in those ancient times before the evil Bush monster plunged us into an economical Dark Age-- Radio Shack used to have a simple little kit used the TL499AC chip to make a 1.3v - 9v converter. One battery poduced 20 ma; two AA cells produced 60 ma at 9 VDC.

You can't get the kit any more, but I do think ya can get the TL499AC chip by itself from Digikey. At least, they had it a few years ago... :-)

Lancelot59

I found it here. Not the exact name though.

Doc Orion

I used the converter kit first to see if it could power my screwdriver which is more sophisticated than the Romana design.

The Romana design is less complicated-- only 1 chip (and somebody clever could probably do it with only a few transistors)-- but if the TL555 low power timer IC is used, it could be run off of a single battery or two, depending upon the battery used. Radio Shack has (still?) a 3.6 v ni-cad cell that might work.

Didn't there used to be a cylindrical 22 volt battery? Anyway, that would work nicely with a voltage regulator to drop the supply down to 15 volts. As Mr. Spock would say, there are always possibilities. One could even make a simple converter from a few spare parts--

http://www.rowan.sensation.net.au/el...cs/stepup.html

Still, it's always good to have a few catalogs from battery companies sitting around; you never know what you might find that will make a sonic screwdriver smaller, more compact. :-)

'Doc

Doc Orion

At this website --

http://books.google.com/books?id=-sE...page&q&f=false


there are a number of basic transistor circuits that can make for great tiny driver circuits. Use two power transistors, work out the R/C values to get 13-15kHz operation, and use a miniature audio step-up transformer and it's finished. The screwdriver will easily operate at 1.5 volts.

The only problem is that the circuit will not only put out more power at 3.0 volts, but the frequency will change as the supply voltage changes. Of course, one could always use 3volts for maximum power to start with (you don't want to de-polerize the ceramic transducer) and at 13 kHz but as the power drops, so would the frequency. But hey, it's just a toy, right? <w>

mintigo

This is actually very interesting. I must consider myself a big Doctor Who fan myself, but I don't have a tremendous knowledge in Physics - I'm still learning at this point. :) But I would really like to build something like this, a device that uses sonic waves to perform actions such as loosening screws. I've read through this entire thread, but as I'm still quite new to physics, I'd greatly appreciate a little help with this topic. Does anyone have any handy tips or a simple guide or steps for me to follow to achieve this?

As I said, I'm looking to design a simple device at this point, so thanks for any help! :D

-Mintigo

Doc Orion

I don't know about the Doctor's current screwdriver with 29 computers built into it, but his earlier designs were as simple as they can come; Electronics 101 kind of stuff-- 2 easy to get IC chips (XR2206 function generator and CD4046 PPL chip) and a handful of small parts, basically. The design doesn't include the battery converter, which I consider a separate system.

1. The XR2206 generates a variable frequency sine wave and requires 3 resistors, a capacitor, and a pot.

2. CD4046 configured as a VCO (voltage-controlled oscillator) needs two caps, a resistor, and a pot. This is really simple.

3. A resistor connects the sine wave oscillator to the VCO; a couple of resistors connect a pair of transistors and a [miniature] transformer in a push-pull amplifier to drive a ceramic transducer. It's really harder to describe than it is to build.

I had designed the entire screwdriver using Turbo-CAD, an inexpensive but sophisticated CAD package. But when my laptop crashed, all of my files went with it. Fortunately I had paper printouts for machinists to make the outer casing, which isn't simple at all. I had taken drafting and machine shop in high school, but I don't have the kind of machine lathe to cut out the separate parts of the casing

The Romana-screwdriver is nothing more than a 15 kHz power oscillator. It works, but it lacks the style and elegance of the Doctor's screwdriver. :-)

'Doc

mintigo

Hi Doc! :)

Thanks for your prompt response. I actually like the previous sonic screwdriver models, as apposed to the current one. And if I am to create one, I would base it off the previous model.

So, to build the screwdriver - I would just require all of the components you've listed above? And then I just piece it all together?

Thanks again!

Doc Orion

It's really a pity that I lost all of my design files. I could probably design it over again from scratch, but that probably wouldn't help you a lot.

But here are a few tips:

The basic XR2206 circuit is very hard to find these days, but here it is--

http://users.ece.gatech.edu/~lanterm...k_2206spec.pdf

The sine circuit is found at fig. 8 and most of the values aren't critical. The main frequency cap should be 1 UF, while the large cap across the grounded resistor needs to be 22 uF. There's a pot in the diagram to determine amplitude, but I *think* I used a
15K resistor for that. The only pot used is the one that controls the frequency from 1 Hz to 100 Hz or thereabouts.

There's a resistor that controls the shape of the sine wave across pins 13 & 14: I think I used 150 ohms, but that's to personal taste and isn't critical either.

The 4046 VCO circuit is even easier. Unfortunately, I don't remember the vaules I used for it. A resistor and a cap at pin 9 (the other end to ground) in parallel determine how slow or fast the main 15 kHz tone shifts. If you use something like 1M/10 uf, it creates almost a slow siren-like sound; well, it would if you could hear 15 kHz, heh heh. Uh, anyway this is part preference, part practicality: at faster cycling speeds, the faster screws can turn so this has to be ballanced out through experiementation. I can't remember the values I picked.

The CD4046--


http://focus.ti.com/lit/ds/schs043b/schs043b.pdf

-- does need a 0.001 uF cap at pins 6 & 7 to get 15 kHz but this is an easy frequency as the VCO can work as high as 1 MHz. Sound that high can't even travel through air more than a few inches before-- well, let's just say it can't travel through air very far. But at 15 kHz, that's not a problem. I think there's a resistor from pin 11 to ground to control the base frequency, ut it has been a long while since I made this circuit.

Lastly, output put the 2206 at pin 3 goes via a resistor to pin 9 of the 4046 so the 15 kHz square wave is modulated by the 1 to 100 Hz sine wave. The output of the 4046 from pins 2 &3 go via 2.2k resistors into a pair of power transistors, simple push-pull kind of arrangement (I think that's what I did), into whatever miniature audio transformer you can get-- especially if it has a good turns ratio. And the screws go round and round... :-)

I suppose if you are just learning electronics-- or don't know any at all-- this is moderately difficult. The main matter like I said before, is wiring it all together so the circuit is tight and fits inside an aluminum tube, not a square box which would be normal for such a circuit.

But it's murder for me to try and rebuild the circuit from memory. This is the reason for always keeping backup files, sigh...

'Doc

Doc Orion

Oh, yeah: I used the XR2206 because a sine wave gives a nice, smooth, modulation but other wave shapes can be used. A LM555 could be used instead to give a sawtooth modulation that sounds real freaky.

It sounds kinda cool, as such things go, but a sawtooth wave has harmonics (sine waves don't) and those harmonics might cause a conflict that makes the screwdriver inefficient. Same for square wave modulation. It also sounds awful. Unfortunately there aren't any easier ways to get a sine way other than the function generator chips like the 2206 or the MAX8038.

'Doc

fengbao

It sounds kinda cool, as such things go, but a sawtooth wave has harmonics (sine waves don't) and those harmonics might cause a conflict that makes the screwdriver inefficient.

Doc Orion

The Doctor and Romana weren't the only ones to have waay cool sonic devices; dig up a copy of the Flint movies from the 60s. Super spy Derek Flint had a sonic belt buckle that he used to first blow up a pool ball, and later used it to escape from a freezing chamber. I think the movie was In Like Flint, starring the late great James Coburn.

Flint's device is a bit more complicated: it produced a series of tones in brief steps-- 100Hz, 300 Hz, 500 Hz, 800 Hz, etc. The transducer looks like a miniature tuning fork, and when he plugged it in the socket, it activated the unit. A really clever design but probably a lot of work for someone heh heh.... ;-)

'Doc

Doc Orion

Hey, I came across a box of Screwdriver parts. Most of them stock items-- resistors,
ICs, etc. But here's something I forgot: to help reduce space, I used some exotic bullet
caps I bought from Mouser #74-173D25V10. The stock number means a 10 uF, 25V tantalum cap made by Vishay/Sprague. I used these bullet caps because they are small and compact; easy to fit into a cylindrical casing without sticking up or anything.

They fit between the three resistors needed for the XR2206 circuit or can fit along side of the resistors but either way, these bullet caps are a clever way to make the circuitry compact short of using surface mount parts. But hey, feel free to use whatever parts or methods you want; this arrangement has just worked pretty well for me. ;-)

The only thing left to ponder over is the transducer. I knocked onetogether from some 0.500" dia. piezo ceramic disks I bought from somewhere. The disks are incredibly thin-- they have to be-- and are bonded to a slightly larger brass disk. This is the way standard piezo buzzers are made, only commercial units are made much more neatly. I don't know the resonant frequency as each transducer has an infinite number of variables so it's just easier to make make them and hope they work. By the way, a special electrically conductive adhesive/glue is needed between disks.

Commercial elements can be used, if ones can be found ssmall enough. They do make a 12 kHz element, or at least they used to. This, I guess is all I can say except for,
good luck folks.

'Doc