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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: steve30 on December 16, 2008, 09:36:23 PM
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Does anyone here have a light pen for the Amiga?
I am interested in getting one to use with my Amigas, but I don't really know much about what models that are avaliable. I also read somewhere that it is possible to make your own. Could anyone provide any information on this?
Thanks
Steve
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A light pen is little more than a photo transistor with a lens plus a button. I think the ones for the C64 work an the Amiga, too.
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As far as i can remember you're right the one for the C64 work on the amiga too, i even think that any lightpen with a standard joyport may work.
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So it might really just be a case of somehow conntecting a phototransistor to the mouse port?
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Lightpens only work on CRTs... does anyone even have a CRT any more?
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Yes. I use a Multisync for 15kHz Amiga pictures, which believe it or not, do not work on my VGA monitors.
I see the mouse port has Penpress, Beamtrigger, and Button 2.
I can assume that Button 2 is the right mouse button.
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"Lightpens only work on CRTs... does anyone even have a CRT any more?"
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Yep, bought my first flatscreen monitor on Saturday. Was using a 6 year old CRT up until then on my PC. On the Amiga I have a 12 year old M1438s.
Of course I found out the first disadvantage of a flatscreen: this monitor has a red stuck pixel. So it is going back this weekend. Other than that it is a lot better than the CRT it replaced.
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bloodline wrote:
Lightpens only work on CRTs... does anyone even have a CRT any more?
Here in the states we don't have SCART connectors so out options are
Amiga with scandoubler to VGA LCD
Amiga 1084 monitor via RGB
or Composite display to TV or LCD TV
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So, is Beamtrigger what I would connect the phototransistor to? Then Penpress is what I would connect a switch to, as this would act as touching the screen aka pressing the left mouse button?
Would I need any special software in order to use a light pen?
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Crom00 wrote:
bloodline wrote:
Lightpens only work on CRTs... does anyone even have a CRT any more?
Here in the states we don't have SCART connectors so out options are
Amiga with scandoubler to VGA LCD
Amiga 1084 monitor via RGB
or Composite display to TV or LCD TV
CRT doesn't mean SCART, it means Cathode Ray Tube.
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bloodline wrote:
Lightpens only work on CRTs...
Good point, forgot about that.
Scandoubled VGA output may also be a bit of a problem, anywhere from reduced accuracy to no reasonable function at all.
Edit: here's an Atari project which would surely work on an Amiga, too: http://www.atariarchives.org/ecp/chapter_6.php
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bloodline wrote:
Lightpens only work on CRTs... does anyone even have a CRT any more?
Hell yes, my Trinitron can be pried from my cold, dead hands :-).
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Were lightpens ever actually good for anything, or just a silly gimmick?
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Were lightpens ever actually good for anything, or just a silly gimmick?
Pretty cool actually, esp. on the Amiga (on the 64 accuracy was rather limited by HF output). The only thing I was missing was a horizontal table monitor since it's very tedious holding up your hand all the time.
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funny the interest.
I literally trashed mine last month.
It's not just a phototransistor - you need a little 8pin chip and some discrete components as well. But it's dead easy to make even with limited solderskills.
I'll check if I still have the schematics and post them if so. I only ever used it on the c64 and resolution was just to crude to be useful.
ta
Tom UK
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Does anyone get how these things work? I usually figure things out without having to read up too much, but I just never have been able to understand how using a regular monitor these things know which pixel you're pointing at..
Also same deal with the light guns, like on the NES.. same deal.. how does it know? Must be the same technology..Seems simular.
Thanks,
Neofree
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Pretty simple once you realize that the video output isn't just there but is built up line by line, from left to right. If you slow down time quite a bit then you can imagine the advancing electron beam hitting the phosphor right behind were the light pen currently points at. The phototransistor sends a pulse back to the video chip (Denise) which actually knows where it's currently at and just freezes the current horizontal and vertical counters to the lightpen register. :-D
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My two cents...
I also used the book referenced in the link posted earlier to build my lightpen. You do need the 7400 in between the TIL414 and the port, as it's acting as a "debouncer". You can also substitute a 7414 Schmidt trigger chip, 74121/123 multivibrator, or a simple 555 one-shot to do this. I also highly recommend using as "flat" and dark a pen barrel as you can find. I found the Papermate Comfort-mate® black to do the trick nicely. This helps to prevent false triggers due to reflections from neighboring pixels.
The reasons my pen is sitting unused have been mentioned earlier:
1) Resolution. On the C64, I could only get it to one character (8x8 pixel block). This is why FlexiDraw pens were better - they added special lenses in the nose to allow single-pixel pointing, and they also had one of the smallest buttons, but with the advent of SMT components the buttons are no longer an issue. You may be able to play with some optical components to come up with a better solution (fiber optic couplers?)...
2) Circulation. Yeah, unless your monitor is mounted inside a desk with the screen facing up, then your arm is going to feel like a lead bar in about five minutes. This is why even FlexiDraw didn't sell too many of their excellent pens. Koala pads did much better (and Kurta, et. al.).
3) Software. GEOS and a couple of paint programs allowed for them, but not much else. I wound up using my pen to act as a light-activated tachometer. It worked up to about 20-30KHz, IIRC.
If all that doesn't deter you, then have at it - but I'd still recommend finding a good 1351 mouse.
banzai
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Hmm - I do remember using it on a friend's Amiga as mouse substitute with some kind of driver. I've got no idea if I had that driver, but I can't find it anyway. May have been the one in Aminet (http://aminet.net/package/util/sys/Lightpen).
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by banzai on 2008/12/19 7:20:33
>My two cents...
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>1) Resolution. On the C64, I could only get it to one character (8x8 pixel block). This is why FlexiDraw pens were better - they added special lenses in the nose to allow single-pixel pointing, ...
You sure they were allowing for single-pixel pointing? That would mean more than 320 horizontal positions and even the Amiga and Atari are limited to about 160 horizontal positions in non-overscan mode.