Magic eye circuits for 6E5

[Dylan Distasio]

I was recently lucky enough to receive a few Sylvania 6E5 magic eye
tubes as part of an assortment of nixies and decatrons.

I know these were typically used in radio tuner applications from what
I understand, and I've looked over the datasheet and a few other
resources, but my experience with vacuum tubes and CRTs is very
limited.

I was just wondering if anyone on the list had experience with these
and if possible, could recommend the simplest circuit possible to test
one of these.

[John Rehwinkel]

> I was recently lucky enough to receive a few Sylvania 6E5 magic eye
> tubes as part of an assortment of nixies and decatrons.
>
> I know these were typically used in radio tuner applications from what
> I understand, and I've looked over the datasheet and a few other
> resources, but my experience with vacuum tubes and CRTs is very
> limited.

Eye tubes are a good start, as there aren't many things to hook up or worry about.

You'll need two power supplies and one resistor as a minimum. The resistor can be 470k to 2meg or so,
1/2 watt or more.

You'll need a heater supply of 6.3 volts (AC or DC). This goes to the big pins (1 and 6).

You'll also need a target supply of 125 to 250 volts DC. Connect the negative lead to pin 5 (cathode),
and the positive lead to the resistor. The other side of the resistor connects to pin 4 (the eye tube target).
This should light up the tube. To close the eye, connect pin 2 (ray control electrode) to pin 5 (cathode).
To open the eye, connect pin 2 to pin 4.

If you have a tube checker, you can use it to light your eye tube as well - the lashup I described above is
equivalent to the tube tester setup.

- John

[Michel]

Maybe this will help:
http://xiac.com/Images/6E5.jpg

They are fun to play with and also simple to drive them, not very
different from a normal triode tube.

Michel

[threeneurons]

Here are some hook-up ideas:

Magic eyes are pretty simple to play with, once you get use to them. As with all "small signal" triodes (the front end of this tube), a voltage negative to its cathode needs to be applied. How negative, determines how wide the pie slice opens. This does not mean that you need a negative supply. A common trick used in the tube era, was a concept called "cathode bias". Current is always flowing thru the tube, from anode (plate [2] and target [4]) to cathode [5]. if you stick a resistor between the cathode, and ground, that current will drop a voltage across that resistor. In the circuit, I chose a 3.3K resistor. If 3mA is flowing thru the tube, then almost 10V will drop across the resistor. So if the grid [3] is at ground, it will be 10V below, or more negative than the cathode, sitting roughly at +10V. With a 200V supply, you'll need to change the grid voltage ~6.5V, to fully open or close, the "shadow", or pie slice.

If you wish to continue playing with tubes, you'll need this site:

http://www.tubedata.org/

All those flags at the bottom are identical "mirror" sites, located all over the world, hence the flags. Click on the American flag, if you're in the US, and it will route you here:

http://tubedata.milbert.com/index.html

Here's Sylvania's datasheet for your tube:

http://tubedata.milbert.com/sheets/084/6/6E5.pdf

And here's a site dedicated to nothing but eye tubes:

http://www.magiceyetubes.com/

Also, there's some goober that made some winker toys, using these tubes:

http://threeneurons.wordpress.com/magic-eye-stuff/

Oh, yeah, that's me ... oops.

[blkadder]

You guys just made my day.  I have a Nixie clock kit with a Dekatron that I am wanting to add a magic eye to help balance out the front of the enclosure I am using.  I think this thread will help this project along nicely.  Thanks guys.

Ron

Semper Fidelis.

[Oscilloclock]

I LOVE the 6E5! It started my long passion in electronics, when my father bought me my first antique radio, a Majestic, at the age of 8. There are a few pix of my radio and its 6E5 at http://oscilloclock.com/history.

The 6E5 was also used in numerous pieces of test equipment - I have a Heathkit capacitance meter and a signal tracer that use them.

Very interesting to see what people have been doing with them recently. Have fun!

[Instrument Resources of America]

The 6E5 was the original "eye" tube, more properly known as "electron
ray indicator", tube. Although I've heard them being referred to as, eye
tubes, tuning indicators, magic eye tubes, bulls eyes, target
indicators, and even bow tie tubes. The 6E5 came out by RCA in or around
the late 1930's perhaps the early 1940;s. My tube collection, has a sub
collection of 75 different eye tubes, most of which still function. My
first experience with eye tubes, was with my dads ancient Magnavox floor
console radio way back in the early 1950's. I wish I still had that old
set, that started my life long interest in electronics. Lots of very
enjoyable hours spent listening to the shortwave and ham bands. Ira.

[Charles MacDonald]

On 13-05-02 11:35 AM, Instrument Resources of America wrote:
> The 6E5 was the original "eye" tube, more properly known as "electron

> ray indicator", tube...... The 6E5 came out by RCA in or around
> the late 1930's perhaps the early 1940;s. ..... I wish I still had that old

> set, that started my life long interest in electronics. Lots of very
> enjoyable hours spent listening to the shortwave and ham bands. Ira.

June of 1935 is shown as the announcement date. "a NEW Electron Ray
tube for indicator use"

If you have the Tube Collectors association Data Cache DVD, the original
data sheet is in file 0033.pdf There was a minor revison of the specs
in 1947. Mostly allowing a T-9 (stright sideed bulb) rather than the ST
12 shape of the original.

The data sheet does have some advice on using the tube in the AVC
circuit of a radio as a tuning indicator, as well as a good explanation
of how it works including a cutaway diagram of the tube.

--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
http://Charles.MacDonald.org/tubes
No Microsoft Products were used in sending this e-mail.

[Instrument Resources of America]

I'm a member in good standing of TCA and YES I do have the "TCA Data
Cache". How could I live without it?? ;)) Ira.

[Instrument Resources of America]

P.S. I was just too lazy to look it up for the original release date.

Ira.


On 5/2/2013 12:06 PM, Charles MacDonald wrote: