23 Apr
2005
23 Apr
'05
7:05 p.m.
Subject: Re: small valves and RE: OT
From: ard at p850ug1.demon.co.uk (Tony Duell)
Date: Sat, 23 Apr 2005 23:45:16 +0100 (BST)
It would be interesting to know what's going on in
this set. Can you get
a schematic? Being an American set, it's not in Poole and Molloy :-(
It's an RCA 8BX5 lineup is 1R5, 1U5, 1T4, 3V5 and 117Z4 if memory serves.
I don't have the schematic for the set. I expent I could find it if needed.
Being functional I'm reluctant to tear into it and hand draw the schematic.
If it breaks I will. Believe it or not I use it to listen to local station
for ball games.
It's one of the better electronics magazines
available over here. It has
some interesting projects, and they've now started making microcontroller
source code available for most, but not all, of them.
I know the magazine, rarely see it.
The circuit in question was a pretty standard inverter
circuit, running
at about 50Hz (not a typo, they wanted to keep RF noise down), feeding a
normal mains transformer used in reverse. Looks like it should work with
no problems.
I've done this before. The simple version use saturated switching
transistors and tend to have high noise due to high current spikes
from charge storage in the transistors. I usually run
them at
100-400HZ with a common mains transformer for better filtering
and use a bit of feedback to run the switch transistors such that
they are turned off before the core saturates. The end result
is less current, better efficientcy and less noise.
It's a side effect of my years of working with older commercial
VHF/UHF twoway radio that used things like vibrators, Dynamotors
and even transistors for generating HT. Often the hybrid and tube
radios would be in service for years after expected retirement
do to replacement cost. The result was desinging and implmenting
replacement circuits that would replace sometimes hard to find
hardware, especially those dynamotors.
Allison
Kb1gmx
24 Apr
24 Apr
2:02 p.m.
Subject: Re: small valves and RE: OT
From: ard at p850ug1.demon.co.uk (Tony Duell)
Date: Sat, 23 Apr 2005 23:45:16 +0100 (BST)
It would be interesting to know what's going
on in this set. Can you get
a schematic? Being an American set, it's not in Poole and Molloy :-(
It's an RCA 8BX5 lineup is 1R5, 1U5, 1T4, 3V5 and 117Z4 if memory serves. I don't have the schematic for the set. I expent
I could find it if needed.
Being functional I'm reluctant to tear into it and hand draw the schematic.
I know the feeling, although doing it while the set is still working
would allow you to note down valve electrode voltages, etc.
If it breaks I will. Believe it or not I use it to
listen to local station
for ball games.
No why on eart hwould oyu want to do that???
[Elektor]
I know the magazine, rarely see it.
Oddly we can get Nuts and Volts and more usefully Circuit Cellar in shops
in the UK... IMHO Circuit Cellar has really gone down over the last year
or so, it seems to be just yet-another-microcontroller-circuit now, and
quite often the microcontroller picked doesn't seem to be the most
appropriate device .Oh well...
-tony
7182
days inactive
7182
days old
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ard＠p850ug1.demon.co.uk