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-   -   An interesting magic eye substitution (https://www.vintage-radio.net/forum/showthread.php?t=8123)

newlite4 22nd Mar 2006 3:26 pm

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

Colin 22nd Mar 2006 4:13 pm

Re: An interesting magic eye substitution
 
What a great idea. And you're right, it is an interesting site.

Mike Phelan 22nd Mar 2006 5:05 pm

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. ;)

Biggles 22nd Mar 2006 5:21 pm

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

XTC 22nd Mar 2006 6:18 pm

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.

YC-156 22nd Mar 2006 7:01 pm

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.

Quote:

Originally Posted by Biggles
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...

There are LEDs with a triangular end shape. The root of the body is rectangular, yet even then you don't have to be very careful when filing them into shape.

Best regards

Frank N.

Brian R Pateman 24th Mar 2006 5:22 pm

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:o ).

Regards,

Nickthedentist 24th Mar 2006 5:33 pm

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;)

Nickthedentist 24th Mar 2006 5:36 pm

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by XTC
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.

I was thinking the same. My £20 DVD player has a greeny-blue fluorescent display, complete with a round "eye" to show if the machine's running in reverse or forward modes and at what speed. It looks very like an old magic eye.

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.

paulsherwin 24th Mar 2006 5:39 pm

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

Nickthedentist 24th Mar 2006 5:46 pm

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by paulsherwin
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.

This soundls like it could be quite simple and look decent, if not completely authentic in its operation:thumbsup:.

Is there any way of getting the right shade of "fluorescent" green, I wonder?

XTC 24th Mar 2006 6:12 pm

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by Nickthedentist
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

I suppose it's hopeless to try making a useful flourescent display without all sorts of sophisticated equipment?

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.

YC-156 24th Mar 2006 7:09 pm

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by Brian R Pateman
We used to carve LEDs up into all sorts of interesting shapes to make illuminated symbols in tiled mimics.

Is there a trick to this, please? I just tried butchering a few LEDs, and I didn't find them particularly forgiving to my ministrations with a hobby knife. :D

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.

Kat Manton 25th Mar 2006 1:28 am

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by XTC
I suppose a matrix of very small LEDs would be close.

Hmm... a circular array of the very small surface mount 'chip' LEDs driven from some sort of microcontroller (there are some with an ADC) programmed to PWM the last LED lit. So, rather than a step change from one LED to the next you get a gradual increase in brightness before the next one lights...

I might add that to my project list ;D

Regards, Kat

YC-156 25th Mar 2006 6:46 am

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by Kat Manton
Hmm... a circular array of the very small surface mount 'chip' LEDs driven from some sort of microcontroller (there are some with an ADC) programmed to PWM the last LED lit. So, rather than a step change from one LED to the next you get a gradual increase in brightness before the next one lights...

That is my idea as well, though you can actually do better than that once you have added the microcontroller. Spent some time yesterday researching this, and it is definitely possible to do on a DIY scale. I even got as far as running a SPICE simulation of the PSU circuit, as that seemed the largest stumbling block. Turns out it isn't. ;D [1]

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.

Brian R Pateman 25th Mar 2006 12:54 pm

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by YC-156
Is there a trick to this, please? I just tried butchering a few LEDs, and I didn't find them particularly forgiving to my ministrations with a hobby knife. :D


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 8-o ).

If we needed vast quantities we could have them made for us by Marl - although they weren't cheap.

Regards,

evingar 25th Mar 2006 1:55 pm

Re: An interesting magic eye substitution
 
Quote:

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
Lumileds do powerful LED for this purpose, negating the need for LED clusters.

http://www.lumileds.com/products/line.cfm?lineId=15

As you say though not cheap -and a bit bright for magic eye applications :o

XTC 25th Mar 2006 2:13 pm

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by Kat Manton
Hmm... a circular array of the very small surface mount 'chip' LEDs driven from some sort of microcontroller (there are some with an ADC) programmed to PWM the last LED lit. So, rather than a step change from one LED to the next you get a gradual increase in brightness before the next one lights...

I wouldn't relish the prospect of soldering all those surface mount bits in place. There seem to be a lot of LED arrays around, and there must be a ready-made one of about the right size somewhere. There are LED arrays which pack an incredible number of small LEDs in place for printers and other applications.

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.

jim_beacon 25th Mar 2006 2:22 pm

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.

YC-156 25th Mar 2006 2:24 pm

Re: An interesting magic eye substitution
 
Quote:

Originally Posted by XTC
It should be possible to take enough power from the heater. 300mA for the ME heater should be going begging for a start.

An EM34 only takes 200mA. ;) Still, that should suffice.

Frank N.


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