"Uncle Peter" ) writes:
"COLIN LAMB" wrote in message
...
Hello Miken:

I If you are going to use integrated circuits in a glowbug receiver, you
need to hide them, since it is unbecoming and might cause others to
ridicule the otherwise heroic effort to recreate a glorious radio. A
simple tube can do a wonderful job of putting out 100 kHz signals, and if
you want 50 kHz, you can use a neon bulb divider.

Many of the simple receivers I built would have been lost with a 100 kHz
marker. A 1 MHz marker would have been more useful, and even then I was
guessing at the which MHz it was. The best marker was simply a crystal in
the ham band and a known point. Something like 3550 kHz, which could also
be used to spot at 7100 kHz. Even odd marked frequencies are useful -
then a properly hand calibrated graph laminated on the front panel (ala
HRO) will give a feeling that none of the wonderful new rigs can touch.

73, Colin K7FM


Colin

do you have a link for using a neon lamp as a frequency divider? This is
the first reference I've seen for this, and I'm fascinated to learn more
about it.

Peter


When I saw Colin start to suggest a tube calibrator, my thought was
"what will you use for a divider, a neon bulb?"

But like him, I can't put my fingers on a circuit. Undoubtedly
somewhere someone did build a crystal calibrator with a neon divider
to get closer together markers, before there were IC dividers.

Another common place would be electronic organs, they'd use neon
bulb dividers to get the next lower octave from a master oscillator.

I'm sure in those "101 things to do with Neon Bulb" books, or even
the wide coverage articles in the magazines, would have a divider.

One Rufus P. Turner book I do have from the tube era has no such
dividers.

I can't find the one book about electronic musical instruments that has
a lot of organ circuitry, which likely does have dividers.

Tube era frequency counters likely used them to some extent.

I am blank about how they worked. It may be like a synchronized
oscillator, using the crystal oscillator to sync a free running
neon bulb multivibrator.

There were also pulse counters, collect pulses until they voltage
of the collected pulses trigger something and it starts over again.

I'm sure I've seen the basic principle, whatever it is, used with
unijunction transistors and even 555s, they all operate basically
the same. But I sure can't find an exact reference in the books
I have handy.

Michael VE2BVW

Hi Michael:

I know I have seen at least a few circuits, but so far I have not put my
eyeballs on one. I checked QST back to 1950, being distracted a bit when I
came upon the Clipperton Island DXpedition. Also checked a number of Hints
and Kinks.

Even used Google. I found a number of references to them, but no actual
circuit. Although they were used in electronic organs, I know I have seen
crystal calibrator circuits using them.

Shhhhh. Please do not let my wife know that, with bookcases spread out all
over I cannot find the circuit. Her idea is that if I have not looked at
something in the last 15 minutes, I should discard it - even though she
still keeps her old clothes she does not fit into anymore.

And, remember that the neon bulb also makes a nice low current screen
regulator, too. (oh, oh, now someone will ask for that circuit.)

Back to the library,

Colin K7FM

In the process of looking for the neon bulb divider, I found a few circuits
using a ECC81, or a 12AU7 or a 6U8 divider - and one circuit even using a
simple rc oscillator locked by the 100 kHz crystal to yield 50 kHz signals.
That was in QST.

73, Colin K7FM

Michael Black wrote:

snip

I am blank about how they worked. It may be like a synchronized
oscillator, using the crystal oscillator to sync a free running
neon bulb multivibrator.

Neon bulb bistable multivibrators were staples of low speed digital
counters and of course electronic organs; the circuit relies on
hysteresis of twin bulbs connected through a common (cathode)
resistor. I may post links to some example implementation diagrams.

There were also pulse counters, collect pulses until they voltage
of the collected pulses trigger something and it starts over again.


One can use a charge pump (diode pump) to accumulate (constant
width and amplitude) pulses until neon bulb breakdown potential
is reached and the bulb discharges the output capacitor restarting
the cycle.

Regards,

Michael

In article ,
Michael Black wrote:
do you have a link for using a neon lamp as a frequency divider? This is
the first reference I've seen for this, and I'm fascinated to learn more
about it.

Peter


When I saw Colin start to suggest a tube calibrator, my thought was
"what will you use for a divider, a neon bulb?"

But like him, I can't put my fingers on a circuit. Undoubtedly
somewhere someone did build a crystal calibrator with a neon divider
to get closer together markers, before there were IC dividers.

Another common place would be electronic organs, they'd use neon
bulb dividers to get the next lower octave from a master oscillator.

I'm sure in those "101 things to do with Neon Bulb" books, or even
the wide coverage articles in the magazines, would have a divider.

There's a section in my GE "Glow Lamp Manual" on neon dividers.


sync in -------------+
|
250 V ----/\/\/\---+---|*|-----+------|*|-----gnd
5.6M | n1 n2
|
+------|(-----+-------|(----gnd
| c1 | c2
| +------- output
|
|
+------|(-----+-------|(----gnd
c3 | c4
+------- sync output

C2 = 10 * C1 (For 200 Hz output, .005 and .05 uF)
C3 = C4 = 100 pF

The problem here is that neon bulb relaxation oscillators top out
at, according to the charts in the book, at between 10 and 30 kilohertz,
depending on bulb type.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

"Mark Zenier" wrote in message
...
In article ,
The problem here is that neon bulb relaxation oscillators top out
at, according to the charts in the book, at between 10 and 30 kilohertz,
depending on bulb type.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)


I was curious if there was a limit on the upper frequency, and I was
wondering
about the waveform as well; that is if the circuit can produce strong
harmonics
up into the upper HF regions. It would be an interesting project to build!

Pete

In article ,
Uncle Peter wrote:

"Mark Zenier" wrote in message
...
In article ,
The problem here is that neon bulb relaxation oscillators top out
at, according to the charts in the book, at between 10 and 30 kilohertz,
depending on bulb type.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)


I was curious if there was a limit on the upper frequency, and I was
wondering about the waveform as well; that is if the circuit can produce
strong harmonics up into the upper HF regions. It would be an interesting
project to build!

The book is pretty vague on the speed of a discharge. Neon lamps
are sloppy parts. They age, their characteristics vary by how much
illumination they get from other lights (or built in radiation), they
take tens of milliseconds to settle down after they've turned off, etc.
So the discharge speed is a pretty loose spec.

Scanning the scope photo of a 7 kHz oscillation and feeding it into
The Gimp (Linux's equivalent of Photoshop), it looks like the fall time
of the sawtooth is about 30 microseconds, out of a total cycle of 140
microseconds. (A 4.7 meg resistor, a 50 pF cap, and an 5AB (a tight spec
NE-2), at 140 volts). Even using just the steepest part, it doesn't look
like there would be harmonics there much higher than 100-200 kHz. High
impedance makes the waveform pretty squishy.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)