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 Post subject: My new Magic Eye
PostPosted: Feb Sun 04, 2018 10:41 pm 
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Joined: Nov Wed 08, 2017 11:52 pm
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Location: Arizona
What do you guys think of my new LED Magic Eye? I have seen a couple versions of a solid state magic eyes but I believe that all of them had some shortcomings. So, I decided to design my own plug and play for my existing EM34, however it could be adapted for almost any other Magic Eye. Here are some pictures and a video.

Image

Next to my crusty 69 years old EM34
Image

Image

Image

Here is a short video with my Philips radio http://www.upss.com/led-me.mp4


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Sun 04, 2018 10:49 pm 
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Location: Crossville, TN USA
Beautiful - I really like that. Would like to see that in my Zenith!
Very creative!
Joe


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Sun 04, 2018 10:53 pm 
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Looks good so far. How about a photo of it lit up and installed? :mrgreen:


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Sun 04, 2018 11:32 pm 
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Very nicely done! A little bit of a diffuser panel in front of it, and it will look really sharp.

You should make a video of it side-by-side with a real one!

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 Post subject: Re: My new Magic Eye
PostPosted: Feb Sun 04, 2018 11:37 pm 
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Location: Jackson, TN
Wow, that is fantastic. Please keep us updated.

Tim


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Sun 04, 2018 11:40 pm 
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Location: S. Dartmouth MA 02748-1225 USA
Kudos!

Looks like you have had boards spun...

Consider a kit?

Variation in the front display for other "look" of eye tubes, like the 6T5?

Inquiring minds want to know!!!

This would be great for the plethora of service grade test instruments with eye tubes, that can be barely seen in the shop lighting!

Chas


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 1:20 am 
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Location: Arizona
I am not considering a complete kit, all the parts are practically off-the-shelf. However, I made some extra board sets (Control and LEDs) which is the key for this design and if there will be some interest I will offer them for sale.


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 1:39 am 
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Hello Upsss,
very nice job looks like a nice deign and love the circuit board


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 1:40 am 
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Can you build them and sell them for about $20? Some people might like one just because it is different BUT most radio restorers will go for an original which is still only $25- 30 unless you make them as replacements for some of the rarer tubes, in which case there is not a large demand - - - YET. Time will most likely make them more valuable.

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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 2:10 am 
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Location: Dayton Ohio
That is a cool idea!

The only criticism I will give is tying pins 2 and 8 together may be an issue for some radios.
Granted, I understand why its needed. It just wouldn't be a universal solution without maybe a small isolation transformer.

-Steve

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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 2:24 am 
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Joined: Nov Wed 08, 2017 11:52 pm
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Location: Arizona
I may be wrong but I am not aware of radios without a power transformer and with a magic eye tube.


Last edited by upsss on Feb Mon 05, 2018 2:32 am, edited 1 time in total.

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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 2:31 am 
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Location: Crossville, TN USA
I had a Pilot 11 tube table model with no transformer. But not very common I guess.


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 2:42 am 
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Location: Arizona
phlogiston wrote:
Can you build them and sell them for about $20? Some people might like one just because it is different BUT most radio restorers will go for an original which is still only $25- 30 unless you make them as replacements for some of the rarer tubes, in which case there is not a large demand - - - YET. Time will most likely make them more valuable.

Only the Chinese will be able to build them by the millions and sell them for $20. Don't forget that a magic eye tube is good only for about 1000 hours.


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 2:45 am 
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Location: Dayton Ohio
Just saying some radios have a power transformer with a 6.3 volt Center Tap winding for the heaters.

The center tap is grounded.

If pin 2 is grounded as well, then this presents a short across half of the heater winding, putting a strain on the power transformer and reducing heater voltage in half.

A 1:1 transformer handing 6.3 VAC in the milliamp range would be quite small. It may fit in the base of the socket, but some changes would need to be made.

I'm not trying to be a problem, just pointing out a possible "gotcha".

Here is a modification of the schematic. Granted, its rough… sorry about that.

-Steve


Attachments:
LED-ME.jpg
LED-ME.jpg [ 65.35 KiB | Viewed 1176 times ]

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-Pre-War FM
Consoles and floor models, the bigger, the better!
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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 3:13 am 
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Joined: Nov Wed 08, 2017 11:52 pm
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Location: Arizona
I can see a 12v filament winding with a center tap grounded but why would you have a 6v filament with a center tap grounded? Can you show me a schematic like that?


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 4:00 am 
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Joined: Nov Fri 10, 2017 4:42 pm
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Location: Western, Kentucky
This led eye tube is one of the better ones I have seen.

I agree with Palegreenthumb about a diffuser, if you can find the right one this will be spot on.

Great job.


Kidd


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 4:10 am 
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Joined: Nov Wed 08, 2017 11:52 pm
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Location: Arizona
I have tried different diffusers but nothing I had looked better than without any, at least in my opinion. Do you guys thing I should try green diffusers?


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 4:16 am 
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Location: Detroit, MI USA
upsss wrote:
I can see a 12v filament winding with a center tap grounded but why would you have a 6v filament with a center tap grounded? Can you show me a schematic like that?


It's very common to have center tapped filament windings, to reduce stray hum pickup. The Detrola 147/Truetone D724 is a really popular collector radio, and uses that configuration.

http://www.nostalgiaair.org/pagesbymode ... 003889.pdf

Zenith liked to use center tapped filament windings on their sets as well, the 12 tube 1940 models are an example:

http://www.nostalgiaair.org/pagesbymode ... 024743.pdf

There were also hundreds of series string radio models built with tuning eye tubes. You couldn't directly use this in a series string as a power resistor would be needed to drop the missing filament voltage and maintain continuity in the filament string. Some sort of combination of a power resistor and small isolation transformer such as Steve proposed earlier would be required to make it work.

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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 4:29 am 
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Joined: Nov Wed 08, 2017 11:52 pm
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Location: Arizona
Well, I was wrong, thanks for the info.


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 Post subject: Re: My new Magic Eye
PostPosted: Feb Mon 05, 2018 3:00 pm 
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Joined: Jan Mon 28, 2013 9:35 pm
Posts: 1053
Location: Santa Rosa, CA
Nicely done in all respects! Not only the boards, and design but your
documentation. Have always wanted to try one of these and would be
very interested in a board set.
Steve

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