Stylus predicament and question

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keithbyrd

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I haven't made one of these in a long time but a friend asked for a stylus with the senor/touch pad on both ends. he wanted it to be 7" long. I made one, put a 1" brass tube on each end and assembled the sensors/touch pad. But it doesn't work. I can hold the pads in my hand and it works but on the stylus shaft it does not. What is wrong with this picture? How do I correct it?
c5bac9fd-946f-4879-a88c-f413fd7ff5f8.jpg
 
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Possible the 1" tubes are not close enough to pick up the field or whatever in your hand to make the "connection" when you touch the screen. Can you get some long brass tubes (10") and cut to length so it runs full length of the stylus? Drilling will be a challenge though. Maybe to verify put a strip of foil tape down the outside from metal tip to metal tip and see if it works. If it does then the long tube should work.

Looks good if you can make it work even better.
 
When a user grips a conventional stylus, his index finger is in close proximity with the barrel for around 3". Without going into a lot of technical detail for why this is, my electrical engineering background leads me to suspect that Pete's suggestion is right - the problem is that using only 1" of tube doesn't provide enough capacitive coupling to the user's hand and therefore the stylus can't work.

There are two ways to increase capacitive coupling - decrease the thickness of the dielectric, or increase the surface area of the conductors that make up the capacitor. The dielectric in this case is the turned barrel, and you probably can't make it thin enough to make a difference without compromising its mechanical strength. So the other option is to increase the surface area of the conductors, which means make the tubes longer.

For those who want details - - - https://www.techwalla.com/articles/how-does-the-stylus-for-an-ipad-work

But that begs the question - why does your friend want a double-ended stylus? You can only use one end at a time - - -

Incidentaly - for many years, I used an iPod Touch for e-mail and web access when not at home, and I found that using a stylus was very helpful. Later, I upgraded to a full iPhone, and while I still have my stylus, I rarely use it anymore. I'm sure that a stylus would help avoid the 'fat finger' problem, but frankly I just don't want to be bothered with having to schlep along a stylus in addition to whichever fountain pen I've selected from by EDC rotation. Also, my sense is that a stylus doesn't work as well with an iPhone as it did with the iPod Touch. Same stylus, iDevices are both Apple, but I don't understand why they behave differently.
 
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monophoto said:
But that begs the question - why does your friend want a double-ended stylus? You can only use one end at a time - - -
Click to expand...
Unless you use one end on a tablet while the other end is working on the phone you're holding in your mouth.

Err... not that I'd ever do something like that.

*hides double-ended stylus behind back*
 
PSI has 10" tubes.

www.pennstateind.com

10inch 7mm Pen tubes - Pack of 10

10inch 7mm Pen tubes - Pack of 1010inch 7mm Pen tubes - Pak of 10 Have you ever found yourself short on tubes because of a ruined blank? Problem solved! Make spare tubes by cutting these 10 inch tubes to the exact size you need.
www.pennstateind.com
 
keithbyrd said:
thanks Jim!
Click to expand...
Yes, PSI is a great place to get 10" tubes.

FYI, you may see brass tubing on display at your local hardware store. BE CAREFUL - I bought some thinking that I could use it in making pens, and found that while the OD matches the brass tubes included in pen kits, the ID is very slightly smaller (ie, the wall thickness is greater), meaning that the kit components wouldn't fit.

I suppose it could be reamed out, but I didn't try.

The point is that the brass tubes sold as part of pen kits is not the same stuff sold in hardware stores, and you can't readily combine the generic stuff from hardware stores with components in pen kits.
 
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