Eric
Going over the material again I have to agree with you. The timing
capacitor reduces in value by 10 for every 10 fold increase in frequency
of course. So at 10kHz it has a value of 47pF (from the pdf I posted)
and below that stray capacitance will dominate. Perhaps the limit would
be a 32768Hz crystal and a series of divide by 8 stages for the
technique but not much higher.
Grahame
On 11/02/2014 22:47, Tidak Ada wrote:
Graham,
Reading some schema's I got in the meanwhile, it looks as the phantastron
isn't able to divide frequencies in the MHz region.
Yours starts at 60 c/s and the HP532A counter from 10 kc/s and below. Is
there any evidence it is possible to divide down from 4MHz to 400 kHz? I am
getting afraid that will be very difficult.
eric
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Grahame Marsh
Sent: dinsdag 11 februari 2014 23:14
To: [email protected]
Subject: Re: [neonixie-l] Phantastron divider
On 11/02/2014 22:07, John Rehwinkel wrote:
I've built a few dividers down to 1Hz and they work phantastically.
Always use the 6AS6 and not just any pentode.
However, Eric said he wanted a low power implementation. Which makes me
wonder if any of the subminiature pentodes out there could be pressed into
service. Due to the way the rod pentodes work, I think they wouldn't work
well. I'm guessing the trick is how G3 causes the current to divide between
G2 and the plate. I may have to grab some tubes and breadboard some stuff.
- John
The heater power alone can be just a killer.
My (poor) understanding is the design of 6AS6 g3 is as a control grid
proper, like g1. And not there to repel secondary electrons from the anode.
I would guess that a given pentode must just be road tested to see if it
will work - as you say time to breadboard something.
G
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