I've been learning about encoders. All the DROs use some kind of
encoder. There many encoder schemes. I like Trav-A-Dials because I can
watch the needle go round and round lots easier than watching a
digital display increment. On the other hand a digital display doesn't
suffer from parallax. Best is both. So, after a little research I
figured out how to add a digital encoder and display to a Trav-A-Dial.
This mod would require reversible modifications to your own
Trav-A-dial that anybody here could do. It could be set up to be
battery operated with the digital display located at the Trav-A-Dial
and a battery life of about 150 hours. Or it could be set up with a
remote digital display connected by a cable to the Trav-A-Dial. The
remote display would be powered by a wall wart. The display would NOT
remember where it is when the power is off, such as when changing
batteries. Anyway, it looks like I can retail these things for around
$100.00 US. If demand was high enough this could be lowered
substantially. So, anybody interested? Should I try to develop this?
Thanks,
Eric R Snow,
E T Precision Machine

Eric R Snow wrote:

I've been learning about encoders. All the DROs use some kind of
encoder. There many encoder schemes. I like Trav-A-Dials because I can
watch the needle go round and round lots easier than watching a
digital display increment. On the other hand a digital display doesn't
suffer from parallax. Best is both. So, after a little research I
figured out how to add a digital encoder and display to a Trav-A-Dial.
This mod would require reversible modifications to your own
Trav-A-dial that anybody here could do. It could be set up to be
battery operated with the digital display located at the Trav-A-Dial
and a battery life of about 150 hours. Or it could be set up with a
remote digital display connected by a cable to the Trav-A-Dial. The
remote display would be powered by a wall wart. The display would NOT
remember where it is when the power is off, such as when changing
batteries. Anyway, it looks like I can retail these things for around
$100.00 US. If demand was high enough this could be lowered
substantially. So, anybody interested? Should I try to develop this?
Thanks,
Eric R Snow,
E T Precision Machine

Please think about including a hold-up capacitor in the power supply
circuit that'll keep it going at least for a while -- having a power
line "blip" reset the thing in the middle of a cut would be a royal pain.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Would this include the encoder and the display, or just the cost of the
modification. We are looking for a dro for our bridgeport clone but
can't afford the $1000 price tag for a decent one.

On Sat, 29 Oct 2005 22:33:08 -0700, Tim Wescott
wrote:

Eric R Snow wrote:

I've been learning about encoders. All the DROs use some kind of
encoder. There many encoder schemes. I like Trav-A-Dials because I can
watch the needle go round and round lots easier than watching a
digital display increment. On the other hand a digital display doesn't
suffer from parallax. Best is both. So, after a little research I
figured out how to add a digital encoder and display to a Trav-A-Dial.
This mod would require reversible modifications to your own
Trav-A-dial that anybody here could do. It could be set up to be
battery operated with the digital display located at the Trav-A-Dial
and a battery life of about 150 hours. Or it could be set up with a
remote digital display connected by a cable to the Trav-A-Dial. The
remote display would be powered by a wall wart. The display would NOT
remember where it is when the power is off, such as when changing
batteries. Anyway, it looks like I can retail these things for around
$100.00 US. If demand was high enough this could be lowered
substantially. So, anybody interested? Should I try to develop this?
Thanks,
Eric R Snow,
E T Precision Machine

Please think about including a hold-up capacitor in the power supply
circuit that'll keep it going at least for a while -- having a power
line "blip" reset the thing in the middle of a cut would be a royal pain.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Greetings Tim,
I would have some sort power backup that would last a minute or two. I
was thinking of maybe a lithium coin cell that would give many minutes
backup. But thanks for the suggestion. It's a good one.
Eric

On 30 Oct 2005 08:46:33 -0800, "woodworker88"
wrote:

Would this include the encoder and the display, or just the cost of the
modification. We are looking for a dro for our bridgeport clone but
can't afford the $1000 price tag for a decent one.

This would include the display and encoder. You would need to supply
the Trav-A-Dial. If you are looking for a complete system look at
Jenix. Two axes. .0002 resolution. An outfit called LMSC sells them.
Follow this link:
http://www.digitalreadoutsystem.com/Jenix/jenix_dro.htm
The price is less than 700 bucks.
Anyway, this is just a proposal right now. I have looked at all the
parts required and quoted the machining like I would a job for someone
else. So even if I started making them tomorrow it would still be at
least a month before any would ship.
Eric

ok

Eric R Snow wrote:

So, anybody interested? Should I try to develop this?

Not that I'd like to have one (for now). But I'd like to integrate it
into my YADRO-project (a DIY-DRO).
If you see any chances that we agree upon a protocol, I'd like to make
the additions to my software.

YADRO can be found he
http://www.motor-manufaktur.de/werkstatt/09_yadro/en_index.html

Enjoy

Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de

On Wed, 2 Nov 2005 19:37:44 +0100, (Nick Müller)
wrote:

Eric R Snow wrote:

So, anybody interested? Should I try to develop this?

Not that I'd like to have one (for now). But I'd like to integrate it
into my YADRO-project (a DIY-DRO).
If you see any chances that we agree upon a protocol, I'd like to make
the additions to my software.

YADRO can be found he
http://www.motor-manufaktur.de/werkstatt/09_yadro/en_index.html

Enjoy

Nick
Greetings Nick,
It looks like, to me, that your scale reader will not work with the
encoder I would use just because the signals are different. The
encoder pulses are simple: A high, B high, A low, B low. High is +5
volts, low is zero volts. When spinning the other direction B leads A.
So the display knows whether to increment or decrement the number
displayed. That said, I'm no electronics guy but you can probably
use your display scheme with different inputs. Since it is software
driven that should be easy for you considering the work you have
already posted about YADRO. My scheme for counting can all be done
with logic circuits. There is no absolute position from the encoder.
And I have to look at the spec sheets of various devices and sample
circuits to come up with electronic designs.
Cheers,
Eric

Eric R Snow wrote:

It looks like, to me, that your scale reader will not work with the
encoder I would use just because the signals are different.

Yes, what you have described is a quadrature encoder. This would require
a different (or modified) digital interface. If you look a shumatech.com
there is such a interface. It reads from a quadrature encoder and on the
other end behaves like a chinese scale. That's what uC are for and very
good in. You should have a look at them. Big fun! Sell your
74xxx-collection at eBay. :-)


My scheme for counting can all be done with logic circuits.

The good old TTL-times. Do they still exist in underground? :-))


There is no absolute position from the encoder.

That doesn't matter. The chinese stuff neither has. You always have to
set a reference point.

But coming back to your TTL-grave (as we call it). How's the output? Do
you intend to directly drive 7-segment LEDs (or such)?


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige