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Amperex #6977 subminiature indcator tube (1958)

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  Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-14 08:28 -0800
    REPOST Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-14 08:33 -0800
    Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-14 11:54 -0500
      Re: Amperex #6977 subminiature indcator tube (1958) Quadibloc <jsavard@ecn.ab.ca> - 2015-12-14 17:07 -0800
        Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-14 23:25 -0500
          Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-15 18:38 -0800
      Re: Amperex #6977 subminiature indcator tube (1958) Quadibloc <jsavard@ecn.ab.ca> - 2015-12-14 17:11 -0800
        Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-14 20:07 -0800
          Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-14 23:29 -0500
            Re: Amperex #6977 subminiature indcator tube (1958) Dave Garland <dave.garland@wizinfo.com> - 2015-12-15 00:15 -0600
    Re: Amperex #6977 subminiature indcator tube (1958) "Osmium" <r124c4u102@comcast.net> - 2015-12-14 11:08 -0600
      Re: Amperex #6977 subminiature indcator tube (1958) scott@slp53.sl.home (Scott Lurndal) - 2015-12-14 17:57 +0000
    Re: Amperex #6977 subminiature indcator tube (1958) jhhaynes@earthlink.net - 2015-12-15 15:54 -0800
      Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-15 19:12 -0500
        Re: Amperex #6977 subminiature indcator tube (1958) Dave Garland <dave.garland@wizinfo.com> - 2015-12-15 19:41 -0600
        Re: Amperex #6977 subminiature indcator tube (1958) isw <isw@witzend.com> - 2015-12-15 23:07 -0800
          Re: Amperex #6977 subminiature indcator tube (1958) Jon Elson <jmelson@wustl.edu> - 2015-12-16 14:32 -0600
            Re: Amperex #6977 subminiature indcator tube (1958) Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-12-16 22:59 +0000
              Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-17 07:30 -0800
                Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-17 15:07 -0500
                  Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-17 13:06 -0800
            Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-17 14:56 -0500
              Re: Amperex #6977 subminiature indcator tube (1958) "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-17 14:12 -0600
                Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-18 19:43 -0500
                  Re: Amperex #6977 subminiature indcator tube (1958) Quadibloc <jsavard@ecn.ab.ca> - 2015-12-20 01:43 -0800
                    Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-20 10:16 -0500
                      Re: Amperex #6977 subminiature indcator tube (1958) "Osmium" <r124c4u102@comcast.net> - 2015-12-20 10:58 -0600
                        Re: Amperex #6977 subminiature indcator tube (1958) "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-21 14:13 -0600
                          Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-21 13:17 -0800
                          Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-21 19:24 -0600
                          Re: Amperex #6977 subminiature indcator tube (1958) Gene Wirchenko <genew@telus.net> - 2015-12-21 18:03 -0800
                            Re: Amperex #6977 subminiature indcator tube (1958) Jon Elson <jmelson@wustl.edu> - 2015-12-22 17:29 -0600
                          Re: Amperex #6977 subminiature indcator tube (1958) Morten Reistad <first@last.name.invalid> - 2015-12-22 14:03 +0100
                            Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-22 12:39 -0600
                              Re: Amperex #6977 subminiature indcator tube (1958) JimP <solosam90@gmail.com> - 2015-12-22 14:37 -0600
                              Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-22 19:45 -0500
                                Re: Amperex #6977 subminiature indcator tube (1958) Ahem A Rivet's Shot <steveo@eircom.net> - 2015-12-23 10:53 +0000
                                  Re: Amperex #6977 subminiature indcator tube (1958) Morten Reistad <first@last.name.invalid> - 2015-12-23 23:42 +0100
                        Re: Amperex #6977 subminiature indcator tube (1958) Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-12-21 21:48 +0000
                          Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-22 07:41 -0800
                            Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-22 11:22 -0500
                        Re: Amperex #6977 subminiature indcator tube (1958) Jon Elson <jmelson@wustl.edu> - 2015-12-21 17:29 -0600
                      Re: Amperex #6977 subminiature indcator tube (1958) "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-21 13:58 -0600
                        Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-21 13:07 -0800
                          Re: Amperex #6977 subminiature indcator tube (1958) "Osmium" <r124c4u102@comcast.net> - 2015-12-21 15:40 -0600
                            Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-21 17:09 -0600
                              Re: Amperex #6977 subminiature indcator tube (1958) "Osmium" <r124c4u102@comcast.net> - 2015-12-21 17:29 -0600
                            Re: Amperex #6977 subminiature indcator tube (1958) Quadibloc <jsavard@ecn.ab.ca> - 2015-12-21 17:03 -0800
                              Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-21 19:28 -0600
                              Re: Amperex #6977 subminiature indcator tube (1958) "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-22 15:46 -0600
                                Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-22 19:13 -0600
                                Re: Amperex #6977 subminiature indcator tube (1958) Morten Reistad <first@last.name.invalid> - 2015-12-23 23:25 +0100
                          Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-21 17:04 -0600
                  Re: Amperex #6977 subminiature indcator tube (1958) "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-21 13:56 -0600
                    Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-21 13:10 -0800
                    Re: Amperex #6977 subminiature indcator tube (1958) Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-12-21 21:48 +0000
                      Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-22 07:42 -0800
                        Re: Amperex #6977 subminiature indcator tube (1958) Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-12-22 16:03 +0000
                          Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-22 11:25 -0500
                    Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-21 16:48 -0600
                      Re: Amperex #6977 subminiature indcator tube (1958) "Osmium" <r124c4u102@comcast.net> - 2015-12-21 17:37 -0600
                        Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-21 18:25 -0600
                      Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-22 07:46 -0800
                        Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-22 11:24 -0500
                          Re: Amperex #6977 subminiature indcator tube (1958) Peter Flass <peter_flass@yahoo.com> - 2015-12-22 11:28 -0500
                            Re: Amperex #6977 subminiature indcator tube (1958) "Osmium" <r124c4u102@comcast.net> - 2015-12-22 15:20 -0600
                              Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-22 19:51 -0500
                                Re: Amperex #6977 subminiature indcator tube (1958) Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-12-23 17:18 +0000
                            Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-22 19:33 -0500
                          Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-22 09:47 -0800
                            Re: Amperex #6977 subminiature indcator tube (1958) "Osmium" <r124c4u102@comcast.net> - 2015-12-22 15:17 -0600
                              Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-22 13:31 -0800
                                Re: Amperex #6977 subminiature indcator tube (1958) Peter Flass <peter_flass@yahoo.com> - 2015-12-22 16:48 -0500
                                Re: Amperex #6977 subminiature indcator tube (1958) Jon Elson <jmelson@wustl.edu> - 2015-12-22 17:43 -0600
                                  Re: Amperex #6977 subminiature indcator tube (1958) Dave Garland <dave.garland@wizinfo.com> - 2015-12-22 19:35 -0600
                                  Re: Amperex #6977 subminiature indcator tube (1958) tracymnelson@gmail.com - 2015-12-23 11:55 -0800
                              Re: Amperex #6977 subminiature indcator tube (1958) Michael Black <et472@ncf.ca> - 2015-12-22 19:50 -0500
                              Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-22 18:56 -0600
                              Re: Amperex #6977 subminiature indcator tube (1958) Quadibloc <jsavard@ecn.ab.ca> - 2015-12-23 02:38 -0800
                                Re: Amperex #6977 subminiature indcator tube (1958) "Osmium" <r124c4u102@comcast.net> - 2015-12-23 13:55 -0600
                                  Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-23 14:12 -0600
                          Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-22 12:28 -0600
                            Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-22 11:06 -0800
                            Re: Amperex #6977 subminiature indcator tube (1958) "Charles Richmond" <numerist@aquaporin4.com> - 2015-12-22 15:58 -0600
                        Re: Amperex #6977 subminiature indcator tube (1958) Lawrence Statton <lawrence@senguio.mx> - 2015-12-22 12:24 -0600
                          Re: Amperex #6977 subminiature indcator tube (1958) hancock4@bbs.cpcn.com - 2015-12-22 11:09 -0800
    Re: Amperex #6977 subminiature indcator tube (1958) terry+googleblog@tmk.com - 2015-12-16 21:33 -0800

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#155178 — Amperex #6977 subminiature indcator tube (1958)

C&A had an ad for this.  Apparently, this unit is intended
to light up, but I'm not sure how it would be classified.

The text says,

The Amperex 6977 is a high vacuum filamentary subminiature
indicator triode which gives a bright blue-green indication
when the control grid is at zero potential.  It has been
developed specifically for transistorized computers, where
its high input impedence and small signal requirements enable
it to monitor the transistor circuits without loading them
and affecting their operation.  It replaces the conventional
and much more expensive high-voltage transistor and neon
lamp combination used so far in transistor computers for 
the same purpose.  Since its high impedence permits 

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#155179 — REPOST Amperex #6977 subminiature indcator tube (1958)

REPOST

C&A had an ad for this, 01-1958.  Apparently, this unit is intended
to light up, but I'm not sure how it would be classified.
 
The text says,

 The Amperex 6977 is a high vacuum filamentary subminiature
 indicator triode which gives a bright blue-green indication
 when the control grid is at zero potential.  It has been
 developed specifically for transistorized computers, where
 its high input impedence and small signal requirements enable
 it to monitor the transistor circuits without loading them
 and affecting their operation.  It replaces the conventional
 and much more expensive high-voltage transistor and neon
 lamp combination used so far in transistor computers for 
 the same purpose.  Since its high impedence permits the 
 use of a series grid resistor, it will not short out the
 transistor circuit if it should ever fail.  Manufactured
 with special computer tube techniques, the 6977 is designed
 for 20,000 hours life.

 Heater voltage is only 1 volt, 30 ma, AC or DC.  The anode
 will only draw 0.5 ma from a 50 volt DC supply during
 the zero-bias  "on" condition.  A 3.0 volt DC voltage is
 sufficient to cut-off plate current and light.  

 AMPEREX ELECTRONIC CORP, HICKSVILLE, NY

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#155181

On Mon, 14 Dec 2015, hancock4@bbs.cpcn.com wrote:

> C&A had an ad for this.  Apparently, this unit is intended
> to light up, but I'm not sure how it would be classified.
>
> The text says,
>
> The Amperex 6977 is a high vacuum filamentary subminiature
> indicator triode which gives a bright blue-green indication
> when the control grid is at zero potential.  It has been
> developed specifically for transistorized computers, where
> its high input impedence and small signal requirements enable
> it to monitor the transistor circuits without loading them
> and affecting their operation.  It replaces the conventional
> and much more expensive high-voltage transistor and neon
> lamp combination used so far in transistor computers for
> the same purpose.  Since its high impedence permits
>
I don't know.

There were "magic eye tubes" that were used for indicators, I seem to 
recall there was a circle at the top, and the more signal, the more of the 
circle lit up.

I think they were related to cathod ray tubes, but can't remember.

They generally had a triode built in, but that was more for amplification, 
if you needed the indicator, you'd need that stage of amplification.

But the description here sounds like something else.

There were eventually lots of devices for displaying numbers, the Nixie 
tube, 7segment LED readouts, but there were some that required high 
voltage but weren't Nixie tubes, and others that used some other process 
but didn't need high voltage.

This thing sounds like an on/off indicator but I'm not sure what process 
it uses.

   Michael

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#155203

On Monday, December 14, 2015 at 9:51:40 AM UTC-7, Michael Black wrote:
 
> But the description here sounds like something else.

Even though the date seems much too early, "bright blue green" makes me think of 
a vacuum fluorescent indicator.

John Savard

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#155206

On Mon, 14 Dec 2015, Quadibloc wrote:

> On Monday, December 14, 2015 at 9:51:40 AM UTC-7, Michael Black wrote:
>
>> But the description here sounds like something else.
>
> Even though the date seems much too early, "bright blue green" makes me think of
> a vacuum fluorescent indicator.
>
> John Savard
>
And there was something in the description that might point to that too.

I couldn't remember what sort of voltage those needed.

   Michael

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#155241

On Monday, December 14, 2015 at 11:22:32 PM UTC-5, Michael Black wrote:

> I couldn't remember what sort of voltage those needed.

from the ad:

  Heater voltage is only 1 volt, 30 ma, AC or DC.  The anode 
  will only draw 0.5 ma from a 50 volt DC supply during 
  the zero-bias  "on" condition.  A 3.0 volt DC voltage is 
  sufficient to cut-off plate current and light.   

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#155204

On Monday, December 14, 2015 at 9:51:40 AM UTC-7, Michael Black wrote:

> There were "magic eye tubes" that were used for indicators, I seem to 
> recall there was a circle at the top, and the more signal, the more of the 
> circle lit up.

My search turned up two references that called the 6977, and in one case its 
European equivalent, the DM 160, "magic eye tubes", but they may not have been 
correct.

John Savard

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#155205

On Monday, December 14, 2015 at 8:11:52 PM UTC-5, Quadibloc wrote:
> On Monday, December 14, 2015 at 9:51:40 AM UTC-7, Michael Black wrote:
> 
> > There were "magic eye tubes" that were used for indicators, I seem to 
> > recall there was a circle at the top, and the more signal, the more of the 
> > circle lit up.
> 
> My search turned up two references that called the 6977, and in one case its 
> European equivalent, the DM 160, "magic eye tubes", but they may not have been 
> correct.

From the ad text, I got the impression it was for a computer panel.
Apparently (from the ad), tube computers could connect to a neon 
light, but transistorized computers could not.  This unit served as
a substitute.

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#155207

On Mon, 14 Dec 2015, hancock4@bbs.cpcn.com wrote:

> On Monday, December 14, 2015 at 8:11:52 PM UTC-5, Quadibloc wrote:
>> On Monday, December 14, 2015 at 9:51:40 AM UTC-7, Michael Black wrote:
>>
>>> There were "magic eye tubes" that were used for indicators, I seem to
>>> recall there was a circle at the top, and the more signal, the more of the
>>> circle lit up.
>>
>> My search turned up two references that called the 6977, and in one case its
>> European equivalent, the DM 160, "magic eye tubes", but they may not have been
>> correct.
>
> From the ad text, I got the impression it was for a computer panel.
> Apparently (from the ad), tube computers could connect to a neon
> light, but transistorized computers could not.  This unit served as
> a substitute.
>
>
That part doesn't make sense.  Nixie tubes, that ran off high voltage, 
could be controlled by solid state devices, just make sure they could 
handle the high voltage.  There's the SN7441 BCD to Nixie decoder in the 
TTL logic family intended for this purpose.

But what this thing may be is the indicator and an interface to low 
voltage, because if you had an indicator that needed high voltage, you'd 
have to do the voltage translation at some point, so why not a special 
device for it.

   Michael

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#155208

On 12/14/2015 10:29 PM, Michael Black wrote:
> On Mon, 14 Dec 2015, hancock4@bbs.cpcn.com wrote:
>
>> On Monday, December 14, 2015 at 8:11:52 PM UTC-5, Quadibloc wrote:
>>> On Monday, December 14, 2015 at 9:51:40 AM UTC-7, Michael Black wrote:
>>>
>>>> There were "magic eye tubes" that were used for indicators, I seem to
>>>> recall there was a circle at the top, and the more signal, the
>>>> more of the
>>>> circle lit up.
>>>
>>> My search turned up two references that called the 6977, and in one
>>> case its
>>> European equivalent, the DM 160, "magic eye tubes", but they may
>>> not have been
>>> correct.
>>
>> From the ad text, I got the impression it was for a computer panel.
>> Apparently (from the ad), tube computers could connect to a neon
>> light, but transistorized computers could not.  This unit served as
>> a substitute.
>>
>>
> That part doesn't make sense.  Nixie tubes, that ran off high voltage,
> could be controlled by solid state devices, just make sure they could
> handle the high voltage.  There's the SN7441 BCD to Nixie decoder in
> the TTL logic family intended for this purpose.

There were certainly (voltage regulator) tubes that glowed, e.g. VT105 
and VT150. I suppose if you were designing a tube to glow, 50VDC would 
be achievable, and you could probably control the color to some extent.

It does look like the 6977 was pretty small. It was a bar-graph 
indicator rather than the "magic eye" pie graph format. It apparently 
was designed to bypass the transistor-neon interface, which was the 
bottleneck.

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#155182

<hancock4@bbs.cpcn.com> wrote:

> C&A had an ad for this.  Apparently, this unit is intended
> to light up, but I'm not sure how it would be classified.
>
> The text says,
>
> The Amperex 6977 is a high vacuum filamentary subminiature
> indicator triode which gives a bright blue-green indication
> when the control grid is at zero potential.  It has been
> developed specifically for transistorized computers, where
> its high input impedence and small signal requirements enable
> it to monitor the transistor circuits without loading them
> and affecting their operation.  It replaces the conventional
> and much more expensive high-voltage transistor and neon
> lamp combination used so far in transistor computers for
> the same purpose.  Since its high impedence permits

Sounds like a transistor era replacement for the 6E5, "seeing eye" tube. It 
was used to carefully tune the radio and match its tuning with the signal 
frequency.  I have some Walkman rip-offs that are hard to tune on FM.. 

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#155184

"Osmium" <r124c4u102@comcast.net> writes:
><hancock4@bbs.cpcn.com> wrote:
>
>> C&A had an ad for this.  Apparently, this unit is intended
>> to light up, but I'm not sure how it would be classified.
>>
>> The text says,
>>
>> The Amperex 6977 is a high vacuum filamentary subminiature
>> indicator triode which gives a bright blue-green indication
>> when the control grid is at zero potential.  It has been
>> developed specifically for transistorized computers, where
>> its high input impedence and small signal requirements enable
>> it to monitor the transistor circuits without loading them
>> and affecting their operation.  It replaces the conventional
>> and much more expensive high-voltage transistor and neon
>> lamp combination used so far in transistor computers for
>> the same purpose.  Since its high impedence permits
>
>Sounds like a transistor era replacement for the 6E5, "seeing eye" tube. It 
>was used to carefully tune the radio and match its tuning with the signal 
>frequency.  I have some Walkman rip-offs that are hard to tune on FM.. 
>

Looks more like a replacement for a neon indicator.

http://www.ebay.com/itm/NEW-NOS-NIB-AMPEREX-6977-VACUUM-ELECTRON-TUBE-/151081091818

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#155236

These things were much smaller than "magic eye" tubes.  And much earlier than
ICs.  We used a lot of them in the GE-635 computer family, where they were
called "green worms" by the field service guys.  For some reason we switched
to transistor-driven neon indicators later on - somebody didn't like the green
worms.  The first ones I ever saw were in the old Packard-Bell PB-250
minicomputer.

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#155237

On Tue, 15 Dec 2015, jhhaynes@earthlink.net wrote:

> These things were much smaller than "magic eye" tubes.  And much earlier than
> ICs.  We used a lot of them in the GE-635 computer family, where they were
> called "green worms" by the field service guys.  For some reason we switched
> to transistor-driven neon indicators later on - somebody didn't like the green
> worms.  The first ones I ever saw were in the old Packard-Bell PB-250
> minicomputer.
>
But were they like "magic eye" tubes?  I gather they were simply on/off 
indicators, but I brought up the magic eye tubes that was a possibility, 
and if it wsa just on/off, they only need a spec of the display area.

Somewhere, I remember seeing some piece of stereo equipment that had 
rectangular magic eye tubes, but I can't remember what, or even what they 
were indicating.

   Michael

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#155240

On 12/15/2015 6:12 PM, Michael Black wrote:
> On Tue, 15 Dec 2015, jhhaynes@earthlink.net wrote:
>
>> These things were much smaller than "magic eye" tubes.  And much
>> earlier than
>> ICs.  We used a lot of them in the GE-635 computer family, where
>> they were
>> called "green worms" by the field service guys.  For some reason we
>> switched
>> to transistor-driven neon indicators later on - somebody didn't like
>> the green
>> worms.  The first ones I ever saw were in the old Packard-Bell PB-250
>> minicomputer.
>>
> But were they like "magic eye" tubes?  I gather they were simply
> on/off indicators, but I brought up the magic eye tubes that was a
> possibility, and if it wsa just on/off, they only need a spec of the
> display area.
>
> Somewhere, I remember seeing some piece of stereo equipment that had
> rectangular magic eye tubes, but I can't remember what, or even what
> they were indicating.

At one time I had a tuner, probably a Dynaco, that had a EMM801 
rectangular magic eye (about an inch long, maybe 3/8" high). That 
worked the same as the old magic eye tubes, as you tuned the bars 
lengthened from both sides until they met in the middle. I'd forgotten 
that tube had dual bars... the lower one was used analog for signal 
strength, the upper one showed through a mask that said "STEREO", if 
the station was broadcasting in stereo.

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#155250

In article <alpine.LNX.2.02.1512151909570.6255@darkstar.example.org>,
 Michael Black <et472@ncf.ca> wrote:

> On Tue, 15 Dec 2015, jhhaynes@earthlink.net wrote:
> 
> > These things were much smaller than "magic eye" tubes.  And much earlier 
> > than
> > ICs.  We used a lot of them in the GE-635 computer family, where they were
> > called "green worms" by the field service guys.  For some reason we 
> > switched
> > to transistor-driven neon indicators later on - somebody didn't like the 
> > green
> > worms.  The first ones I ever saw were in the old Packard-Bell PB-250
> > minicomputer.
> >
> But were they like "magic eye" tubes?  I gather they were simply on/off 
> indicators, but I brought up the magic eye tubes that was a possibility, 
> and if it wsa just on/off, they only need a spec of the display area.
> 
> Somewhere, I remember seeing some piece of stereo equipment that had 
> rectangular magic eye tubes, but I can't remember what, or even what they 
> were indicating.

They were intended for tuning FM signals properly.

Isaa

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#155270

isw wrote:

> In article <alpine.LNX.2.02.1512151909570.6255@darkstar.example.org>,
>  Michael Black <et472@ncf.ca> wrote:
> 
>
>> Somewhere, I remember seeing some piece of stereo equipment that had
>> rectangular magic eye tubes, but I can't remember what, or even what they
>> were indicating.
> 
> They were intended for tuning FM signals properly.
> 
They were also used, WAY BACK, when TVs had continuously variable tuning.
That would be 1955 DuMont and similar vintage.

Jon

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#155275

On 2015-12-16, Jon Elson <jmelson@wustl.edu> wrote:

> isw wrote:
>
>> In article <alpine.LNX.2.02.1512151909570.6255@darkstar.example.org>,
>> Michael Black <et472@ncf.ca> wrote:
>>
>>> Somewhere, I remember seeing some piece of stereo equipment that had
>>> rectangular magic eye tubes, but I can't remember what, or even what they
>>> were indicating.
>> 
>> They were intended for tuning FM signals properly.
> 
> They were also used, WAY BACK, when TVs had continuously variable tuning.
> That would be 1955 DuMont and similar vintage.

My 1963-vintage tape recorder uses a pair of smallish round magic eyes
for record level indicators.  They also indicate you're recording,
since that's they only time they're lit.

-- 
/~\  cgibbs@kltpzyxm.invalid (Charlie Gibbs)
\ /  I'm really at ac.dekanfrus if you read it the right way.
 X   Top-posted messages will probably be ignored.  See RFC1855.
/ \  HTML will DEFINITELY be ignored.  Join the ASCII ribbon campaign!

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#155281

On Wednesday, December 16, 2015 at 5:59:46 PM UTC-5, Charlie Gibbs wrote:

> My 1963-vintage tape recorder uses a pair of smallish round magic eyes
> for record level indicators.  They also indicate you're recording,
> since that's they only time they're lit.

My 1964 tape recorder (tube based, presumably low-end) used an 
incandescent bulb has the recording-level indicator.   Sensitivity
was adjustable--later cheap recorders used an automatic method.
Anyway, the instructions said little about it optimum recording
level, but by trial and error I got it.

As an aside, audio tapes made back then were not playable in
1984; the sound was just garbled.  

I do remember experimenting with different brands of tapes, 
and brands certainly made a difference.  I liked Scotch tapes.

Some people I knew had a 3M Wollensack recorder; as did the
school.  This was a high quality machine and pretty impressive.
My recorder only took 5" reels and had 3¼ and 7½ ips, I think the
Wollensack had 1 1/8 and 15 ips as well, plus had four track or
two track stereo.

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#155290

[Multipart message — attachments visible in raw view] — view raw

On Thu, 17 Dec 2015, hancock4@bbs.cpcn.com wrote:

> On Wednesday, December 16, 2015 at 5:59:46 PM UTC-5, Charlie Gibbs wrote:
>
>> My 1963-vintage tape recorder uses a pair of smallish round magic eyes
>> for record level indicators.  They also indicate you're recording,
>> since that's they only time they're lit.
>
> My 1964 tape recorder (tube based, presumably low-end) used an
> incandescent bulb has the recording-level indicator.   Sensitivity
> was adjustable--later cheap recorders used an automatic method.
> Anyway, the instructions said little about it optimum recording
> level, but by trial and error I got it.
>
Was the bulb varying with the signal going into the recorder, or just 
kicking in to say "don't talk so loud"?  An "overload" indicator.

> As an aside, audio tapes made back then were not playable in
> 1984; the sound was just garbled.
>
We had a cheap transistor tape recorder from the early sixties.  A decade 
later, I took it apart, it used a magnet to erase the tape, I'm not sure 
if on record the tape head was "biased" (by a high frequency signal). But 
there was also no capstan, so the tape speed vary depending on how much 
tape was on the reel,   So interchangeability was limited, probably worse 
because I bet the tape head wasn't adjusted perfectly, so it skewed on 
another.

I seem to recall that when stereo recorders came along, how they arranged 
the tape head varied, so some couldn't play back tapes from another.

   Michael




> I do remember experimenting with different brands of tapes,
> and brands certainly made a difference.  I liked Scotch tapes.
>
> Some people I knew had a 3M Wollensack recorder; as did the
> school.  This was a high quality machine and pretty impressive.
> My recorder only took 5" reels and had 3¼ and 7½ ips, I think the
> Wollensack had 1 1/8 and 15 ips as well, plus had four track or
> two track stereo.
>
>
>

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