Simple Display Driver

Forum for discussion of narrow-bandwidth mechanical television

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Where there's a will, there's a way...

Postby Steve Anderson » Thu Apr 26, 2007 6:44 pm

Gents,

Here's aforementioned file zipped...

Steve A.
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Re: Drawings.

Postby gary » Thu Apr 26, 2007 7:28 pm

Steve Anderson wrote:Gents,

I have created a sample disc drawing in AutoCad, this is accurate as you could ever wish, however you need AutoCad to print it. There is an 'Export' function to save as BMP etc., but the resoultion is limited to ones screen settings. Frankly useless. See attached. (The slightly elliptical shape is again from the screen settings I use, the final output is spot-on).

The problem is AutoCad costs at least US$3,500, and that was the last time I checked a few years ago. I'm sure in the past I have done hi-res exports, I'll keep playing with it.

Steve A.


There are plenty of free AutoCad drawing (dxf/dwg) viewers with print facilities available on the internet, for example: http://www.edrawingsviewer.com

Not sure if that solves the problem though if one wants to resize the layout, I am not sure if rescaling via the print facility is accurate enough, but then again as long as it is proportional how accurate does it have to be?

Also here is a link to a nipkow disk creator written by Sam Hunt, I haven't used this one in anger but it looks OK:

http://users.tpg.com.au/users/gmillard/viddisc5.exe

(The original site seems to have disappeared)

There is also a php script available for this if we could find a php enabled web server host...
gary
 

Disc drawings.

Postby Steve Anderson » Thu Apr 26, 2007 7:37 pm

Gary,

If you (or anyone else) is armed with printing software for AutoCad .dwg files I'm quite happy to do them to order. It's really simple for me, I've been using AutoCad since the early 80s.

All I need is the crucial data, no. of holes, single or multi spiral, and preferably the outside diameter of where line 1 sits (the most furthest from the centre). And the spacing from line-to-line.

Sync holes can be added too, I just need the same data as above. All I ask is please keep it Metric!

Steve A.
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Re: Disc drawings.

Postby gary » Thu Apr 26, 2007 8:11 pm

Steve Anderson wrote:Gary,

If you (or anyone else) is armed with printing software for AutoCad .dwg files I'm quite happy to do them to order. It's really simple for me, I've been using AutoCad since the early 80s.

All I need is the crucial data, no. of holes, single or multi spiral, and preferably the outside diameter of where line 1 sits (the most furthest from the centre). And the spacing from line-to-line.

Sync holes can be added too, I just need the same data as above. All I ask is please keep it Metric!

Steve A.


Steve, I have confirmed that eDrawings (link above) reads your file OK
(Visio does not for some reason), and that it prints out on my PagePro 1300W printer perfectly.

This free download also opens your drawing, prints, and also allows editing
http://www.a9tech.com/

Personally, as I only have an A4 printer I can get by with some software I have written (actually I have been using a LightScribe DVD Burner to
print directly onto a CD, I then use a modified needle to 'centre punch' the holes and then use a very fine drill to finish off).

However, I am sure others would be pleased to avail themselves of your offer, it seems that if you could produce a few templates the free software mentioned should allow scaling to give any size they could want.

Cheers.
gary
 

Postby Steve Anderson » Thu Apr 26, 2007 8:38 pm

However, I am sure others would be pleased to avail themselves of your offer, it seems that if you could produce a few templates the free software mentioned should allow scaling to give any size they could want.


I'm quite happy to do it, but I feel it's better to do each variation as a seperate identity as scaling things introduces truncation and rounding errors.

Printing at 1=1 is also the best, that way the final print should be exactly correct, even on the cheapest of printers.

Visio is not compatable with AutoCad files, it's a Microsoft product for people who want to draw but can't.

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Postby gary » Thu Apr 26, 2007 8:46 pm

Steve Anderson wrote:
However, I am sure others would be pleased to avail themselves of your offer, it seems that if you could produce a few templates the free software mentioned should allow scaling to give any size they could want.


I'm quite happy to do it, but I feel it's better to do each variation as a seperate identity as scaling things introduces truncation and rounding errors.

Printing at 1=1 is also the best, that way the final print should be exactly correct, even on the cheapest of printers.

Steve A.


Well I actually meant scaling within the editing software which should be very accurate especially if scaling down, but point taken.

And, I suppose, if you haven't already done so, you can write a macro to do the whole thing.

Does ACAD still support lisp as it's interface language? it's been many years (version 9?) since I have used it.
gary
 

AutoCad

Postby Steve Anderson » Thu Apr 26, 2007 9:03 pm

Gary,

AutoCad has come a long way since then, it still supports lisp files, but there's hardly any need for them now. Just have a look at the Autodesk website and you'll see what I mean.

I'm using AutoCad 2008, but I'm not saying how I got it...

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Re: AutoCad

Postby gary » Thu Apr 26, 2007 9:15 pm

Steve Anderson wrote:Gary,

AutoCad has come a long way since then, it still supports lisp files, but there's hardly any need for them now. Just have a look at the Autodesk website and you'll see what I mean.

I'm using AutoCad 2008, but I'm not saying how I got it...

Steve A.


You mean there have been 1999 revisions since I last used it? ;-)

Actually you have reminded me that back in 1983 I bought a Houston Instruments A1 capable plotter for the drawing office at work. When I recently retired I noticed that it was being disposed of and so I gave them $20 dollars for it thinking that the servo motors might be useful (I am thinking of building a small CNC machine). I think it might still work and so I *could* plot out large (> A4) disks, hmmm.... I wonder if there are any Vista drivers for it, hah! :-(
gary
 

Houston Instruments

Postby Steve Anderson » Thu Apr 26, 2007 9:31 pm

Gary,

It would appear that Houston Instuments got swallowed by Calcomp, you might find drivers here that should work with later versions of Windoze..

http://www.calgraphinc.com/Support/Drivers.html

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Re: Houston Instruments

Postby gary » Thu Apr 26, 2007 9:53 pm

Steve Anderson wrote:Gary,

It would appear that Houston Instuments got swallowed by Calcomp, you might find drivers here that should work with later versions of Windoze..

http://www.calgraphinc.com/Support/Drivers.html

Steve A.


Hah! would you believe that? I couldn't find anything on the CalComp site but a quick Google found a site that even has 3.1 drivers! The most recent is W95, that's OK I'll just fire it up on my 426 machine. I even found this:

"Vinyl Cutters:
Here's a very useful piece of information from Tim N. in England:
"One thing worth knowing is that I tried using a vinyl cutting blade holder and blade from a Summa D Series cutter and, after installing a thin bylon protection strip along the plot line and slowing the pen speed right down, my DMP-161 is cutting vinyl signs perfectly!"
Thanks, Tim! "

I might be able to cut Darvic disks directly! I just need a pen sized Dremel :wink:
gary
 

Plotter drivers.

Postby Steve Anderson » Thu Apr 26, 2007 10:24 pm

Gary,

'Most' drivers are backwards compatible, that is, if it were made for Win 95, there's every chance it will work on your current OS, although not guaranteed.

Turning an old plotter into an improvised CNC machine is a good idea, as you say, you'll need to slow down the pen movement and improvise a drill platform.

Depending on your plotter, it may or not handle thick materials...

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Re: Phase inversion?

Postby aa9dt » Sun May 13, 2007 8:31 am

[quote="ac7zl"]

...I keyed in a representative circuit for this schematic into LTSPICE and plotted its behavior.... The circuit seems to start saturating at anything above .25 volts p input, and linearity is poor. Frequency response is poor, as well.

... I used a single LED for modeling purposes, not the array.


Pete
AC7ZL


Your conclusion applies to the circuit you simulated, not the circuit in the schematic. Since you changed the load, the two circuits differ. Using one LED instead of the array upsets the base bias and causes clipping.

You don't mention whether you used a current-limiting resistor for the LED. If not, then the real-world driver would toast your LED.

You also don't mention what input voltage you're using. The driver isn't an NBTVA-standard circuit. Instead, I designed the circuit as a solid-state version of a 1928 Daven television amplifier. (The circuit can work with NBTV recordings, though.) If you follow the 1-volt, NBTVA standard, then you might overdrive this circuit. In normal operation, the user adjusts the CD player's volume control for best output.

The LED driver circuit is from my television Web site, www.hawestv.com/mtv_page/mtv_page.htm . (By the way, my page cautions about parts substitutions.) The page also links to FAQ about the LED driver. In these FAQs, I answer in greater detail.

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Re: Phase inversion?

Postby Roland » Sun May 13, 2007 10:32 am

Hi Jim,

Hoped you join us here. Just to say I found your web site very useful and my current NBTV amp was originally based on your circuits and Ohms law info.

Anyway - quick question on the following statement. I'm using the line out from a portable CD player. Is the volume control supposed to affect the line out or just the headphone socket?

aa9dt wrote:In normal operation, the user adjusts the CD player's volume control for best output.


Thanks

:-)

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Postby Klaas Robers » Sun May 13, 2007 8:58 pm

Of course the cicuit starts saturating when the current becomes more than the collector resistor allows. It is not bad that it is non lineair. The non linearity gives some form of gamma correction. I don't know in how far the shape resembles the gamma curve, i.e. a parabola form. This depends heavily on the parasitic serial resistance of the LED. Not impossible that in certain cases it is to too bad.

Of course a gain control pot at the input is needed and the absence of DC restoration is a pitty. An extra transistor could help here, but then the circuit is going to grow towards the less simple circuits.

Jim, why can I not access the page that you mentioned above?
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Postby gary » Sun May 13, 2007 9:24 pm

Klaas Robers wrote:Of course the cicuit starts saturating when the current becomes more than the collector resistor allows. It is not bad that it is non lineair. The non linearity gives some form of gamma correction. I don't know in how far the shape resembles the gamma curve, i.e. a parabola form. This depends heavily on the parasitic serial resistance of the LED. Not impossible that in certain cases it is to too bad.

Of course a gain control pot at the input is needed and the absence of DC restoration is a pitty. An extra transistor could help here, but then the circuit is going to grow towards the less simple circuits.

Jim, why can I not access the page that you mentioned above?


There's an unnecessary period at the end of the URL. Remove this and it is fine.
gary
 

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