Digital Tape MEasure

[gurliegurl15]

Hey yall~> i was wondering if anyone can help and give me i deas how to bulid a digital tape measure (smart tape) and build into it a blinking light the light really has nothing to do with the project its juss gotta turn on when the tape measure's on and then keep blinking no matta what untill the tape measure's shut off. If ne of us could help itd b greatly appreciated thank u bye yall...[/

 

[Optikon]

Hey yall~> i was wondering if anyone can help and give me i deas how to bulid a digital tape measure (smart tape) and build into it a blinking light the light really has nothing to do with the project its juss gotta turn on when the tape measure's on and then keep blinking no matta what untill the tape measure's shut off. If ne of us could help itd b greatly appreciated thank u bye yall...[/

One idea might be to have your tape wound up on the shaft of an optical encoder with sufficient resolution. As you pull your tape, the encoder outputs an encoded digital signal that is related directly to how much the encoder wheel has turned. This is in turn, related to how much tape has been pulled and so you would have a linear measure.

You would have to account for both increasing and decreasing amounts to keep track of how much tape has been extended. Sometimes, one pulls too much tape out and then lets a little back so you would have to account for that behavior.
The lights thing is easy, there should be many examples on the web google for "blinking LED circuit" etc.. I think you'll find the most difficulty in electronically counting the length of tape dispensed.

 

[fat-tony]

One idea might be to have your tape wound up on the shaft of an optical encoder with sufficient resolution. As you pull your tape, the encoder outputs an encoded digital signal that is related directly to how much the encoder wheel has turned. This is in turn, related to how much tape has been pulled and so you would have a linear measure.

Like the guts of a ball-mouse .

 

[Optikon]

One idea might be to have your tape wound up on the shaft of an optical encoder with sufficient resolution. As you pull your tape, the encoder outputs an encoded digital signal that is related directly to how much the encoder wheel has turned. This is in turn, related to how much tape has been pulled and so you would have a linear measure.

Like the guts of a ball-mouse .

and you do not even need the quadrature nature of it. simplifying things more.

 

[Dean Huster]

Quadrature?

Why would you not need the "quadrature nature" if you're intending on sensing a reversal of the tape? Without quadrature (or some unknown replacement for it), the tape would only see the reversal pulses as more pulled out tape.

The OP never really defined the need. Is this a digital tape measure replaceing a standard Stanley or Evans retractable tape or an ultralsonic measuring device designed for sloppy and questionable measurements (those laser guides are a gimmick) or a replacement for one of those measuring wheels like the cops use to measure the length of skid marks?

Dean

 

[jbeng]

I think you'd definitely need a quadrature setup to tell the computer(?) when the tape was being pulled out of the housing or allowed to reel back in. Also, if the tape was wound around the shaft of the encoder, there would need to be some compensation, because the encoder would turn fewer revolutions when there are more wraps. Think of it this way: put a one-inch diameter wheel on the encoder shaft to simulate wraps of tape. For every revolution of the shaft, 3.14159 inches of tape would be pulled out. Put a 1.25 inch diameter wheel on the same encoder, simulating more tape wrapped aroung the shaft. At that point, for every revolution of the shaft, 3.92699 inches of tape would be pulled out. I think that'll be tricky to compensate for.
JB

 

[Optikon]

Re: Quadrature?

Why would you not need the "quadrature nature" if you're intending on sensing a reversal of the tape? Without quadrature (or some unknown replacement for it), the tape would only see the reversal pulses as more pulled out tape.

The OP never really defined the need. Is this a digital tape measure replaceing a standard Stanley or Evans retractable tape or an ultralsonic measuring device designed for sloppy and questionable measurements (those laser guides are a gimmick) or a replacement for one of those measuring wheels like the cops use to measure the length of skid marks?

Dean

The quadrature nature allows for the detection of FOUR direction.. you only need to detect TWO here.

 

[Sebi]

With a simple circuit and up/down counter not impossible...

 

[jbeng]

Re: Quadrature?

The quadrature nature allows for the detection of FOUR direction.. you only need to detect TWO here.

What I think D.H. is referring to is called "phase quadrature" where two signals are 90 degrees out of phase with each other. That would be what you could use to determine direction of tape travel.

https://whatis.techtarget.com/definition/0,,sid9_gci213803,00.html