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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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22nd Mar 2006, 4:26 pm | #1 |
Octode
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An interesting magic eye substitution
Look at this site for a novel solution :
http://www005.upp.so-net.ne.jp/y_kondo/MAGICEYE2.HTM I suspect that any LED bar-graph driver would work. The rest of the site looks good too, Neil |
22nd Mar 2006, 5:13 pm | #2 |
Heptode
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Re: An interesting magic eye substitution
What a great idea. And you're right, it is an interesting site.
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22nd Mar 2006, 6:05 pm | #3 |
Dekatron
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Re: An interesting magic eye substitution
Wow - that looks like an excellent idea! I have never seen the one with a red centre and what looks like a splodge from a seagull on it, though.
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Mike. |
22nd Mar 2006, 6:21 pm | #4 |
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Re: An interesting magic eye substitution
I'm now inspired to have a go at this. I wonder if you could get realistic results by using the square/rectangular shaped leds and carefully filing one edge to an angle so they fit together in a circular fashion if you understand what I mean...You could even fit these to transistor type sets for a novel look. Do you think that you could fit high voltage drivers on the chip and use it to drive neons in a light bar fashion, akin to some of the linear neon indicators from the thirties?
Biggles |
22nd Mar 2006, 7:18 pm | #5 |
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Re: An interesting magic eye substitution
It's a very good idea, especially in view of the fact that the end view octal MEs are getting expensive and are only bright for a few hundred hours. In a domestic set that has a lot of use, this would be great.
I've sometimes wondered how much it would take to have a round indicator made up using the same technology as the flourescent displays on CD players. It would probably cost a mint. The linear neon indicators from the thirties blackened quickly and had a very short life. Pete. |
22nd Mar 2006, 8:01 pm | #6 | |
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Re: An interesting magic eye substitution
Have to admit that I wonder how well this works in practice, beyond the novelity factor. 10 tuning steps on a magic eye is nothing. An analog display can be read to nearly any desired degree of accuracy, but a device like the LED eye would require some form of scale loupe to funcion as desired. That would be non-trivial to add.
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Best regards Frank N. |
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24th Mar 2006, 6:22 pm | #7 |
Nonode
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Re: An interesting magic eye substitution
LEDs are very forgiving of butchery. In the days before PCs were used in control systems I used to design and build mimic diagrams for control rooms.
We used to carve LEDs up into all sorts of interesting shapes to make illuminated symbols in tiled mimics. (Even the blue Siemens ones which were IIRC abot £18.00 each ). Regards,
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24th Mar 2006, 6:33 pm | #8 |
Dekatron
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Re: An interesting magic eye substitution
The new, LED curing lamps that (extravagant) dentists use to set light-cured fillings apparently use a LED cluster made from dozens of ultra-bright Philips LEDs which are somehow machined so that they fit together in a honeycomb arrangement, resulting in an extremely compact light source. So if major manufacturers do it, surely we can too
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24th Mar 2006, 6:36 pm | #9 | |
Dekatron
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Re: An interesting magic eye substitution
Quote:
But I suspect the cost would be astronomical unless they were being produced in tens of thousands What about a backlit moving-coil display? RS used to do some tiny, round m/c battery-status indicators, which were designed to "wink" a bit like a magic eye according to the battery's voltage. Here's something similar: http://uk.farnell.com/productimages/...5808104-40.jpg Nick. Last edited by Nickthedentist; 24th Mar 2006 at 6:43 pm. |
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24th Mar 2006, 6:39 pm | #10 |
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Re: An interesting magic eye substitution
It's certainly an interesting attempt, but I don't think it's a very convincing replacement.
I've been toying with building several EM34 replacements. One is relatively simple and involves using a high brightness green LED shining on an opaque EM34 shaped screen. This would just get brighter as the signal strength gets higher. It would probably look more like a conventional magic eye once a station had been tuned in. Another is a bit more off the wall and involves using an EM34 shaped decatron (I've got several of these in the junk box). The idea is to have a pulse generator linked to the AGC voltage so the decatron display whizzes round faster and faster as the station is tuned in. I haven't actually built either of these yet Best regards, Paul |
24th Mar 2006, 6:46 pm | #11 | |
Dekatron
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Re: An interesting magic eye substitution
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Is there any way of getting the right shade of "fluorescent" green, I wonder? |
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24th Mar 2006, 7:12 pm | #12 | |
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Re: An interesting magic eye substitution
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I've toyed with the moving coil idea too. The problem is that the display of an end-view magic-eye is very distinctive, so any substitute is going to look a bit naff. I suppose a matrix of very small LEDs would be close. Pete. |
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24th Mar 2006, 8:09 pm | #13 | |
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Re: An interesting magic eye substitution
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The trouble with the EM34 is that it is dual sensitivity, of course. So substituting one of those russian 6E5S things is not a 'proper' replacement, even if you don't mind rotating the valve base. Best regards Frank N. |
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25th Mar 2006, 2:28 am | #14 | |
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Re: An interesting magic eye substitution
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I might add that to my project list Regards, Kat |
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25th Mar 2006, 7:46 am | #15 | |
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Re: An interesting magic eye substitution
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My intention is to use 2,5x5mm rectangular green LEDs, 32 in total, filed or grinded into shape so they can be arranged in a circle a bit less than 25mm in outside diameter. That would provide a much more even light field compared to the original. Frank N. [1] The original PSU circuit referenced at the start of this thread will not do IMHO, as it will force a non-trivial DC component through the mains transformer. |
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25th Mar 2006, 1:54 pm | #16 | |
Nonode
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Re: An interesting magic eye substitution
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Hi Frank, The trick is to use a good quality LED as a starting point. The light emitting "chip" is usually at the base of the device (the standard 5 or 6mm diameter type) and obviously you need to avoid getting too close to it with your knife. The ones I have found best are the oblong type from IMO. There is a good selection available from RS or any of the usual suppliers. We had a Taylor Hobson engraving machine and our engraver would set it up as a milling machine and do batches at a time. For a few off I would think that filing might be better that using a knife (and safer for the fingers ). If we needed vast quantities we could have them made for us by Marl - although they weren't cheap. Regards,
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25th Mar 2006, 2:55 pm | #17 | |
Octode
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Re: An interesting magic eye substitution
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http://www.lumileds.com/products/line.cfm?lineId=15 As you say though not cheap -and a bit bright for magic eye applications
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25th Mar 2006, 3:13 pm | #18 | |
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Re: An interesting magic eye substitution
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Some PIC processors have onboard ADCs. Using a microprocessor would make the project more versatile - programming the sensitivity etc - as well as the dithering you suggest. It should be possible to take enough power from the heater. 300mA for the ME heater should be going begging for a start. I think it's down to getting a display that's convincing enough to be worth the trouble, and which fits. As said earlier. the Tuneon neon indicators in 30s radios are very short lived and are nearly unobtainable. A linear LED array would fit in and be a tolerable sub. Pete. |
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25th Mar 2006, 3:22 pm | #19 |
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Re: An interesting magic eye substitution
The advantage of a PIC would be flexibility. You could easily simulate the dual sensitivity mentioned before, or the multitude of strange patterns (split, cross etc.)
Jim. |
25th Mar 2006, 3:24 pm | #20 | |
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Re: An interesting magic eye substitution
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Frank N. |
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