28 Oct
2007
28 Oct
'07
4:34 p.m.
Hi,
tony said:
The voltages are not that critical. The first time I played with one of
these vales was about 30 years ago. It was certainly when there were 4
Henry's Radio shops in the Edgware Road, because that's where I bought a
little assembly of 4 DM160s from.
Anyway, I rememebr heating the filament with a single AA cell. A bit
overvoltage, and in retrospect I should have added a series resistor, but
the filament didn't burn out. There was a very dull read glow visile in
the dark -- I suspect there should be no glow at all at the right
operating voltage.
For the target supply I used a 22.5V dry battery, probably a B122. That
gave a good green glow. I am sure I've seen 30V quoted in other databooks.
As for the cotnrol grid, it's hard to overvoltage that. Certainly a 5V
swing will do no harm at all, if you want to drive one of these devices
These sound a lot like what we caleld
'DM160's in the UK. These are about
the size of a 1.24" (3AG??) cartridge fuse and have 4 active leads coming
out of one end.
2 of them are a filament (direcctly heated cathode), running at about 1V.
Another is the anode/target, which IIRC has a grid-like structure, It is
normally riun at about 30V +ve wrt the filament. The fourth wire is the
control grid, IIRC with the grid at the smae voltage as the filament the
device glows green, a -3V grid bias cuts it off and it's dark. Needless
to say the actual current drawn y the cotnrol grid from the transistor
logic is minimal/
According to my data book:
Filament 1.0V 0.03A
Target Volts 50V
Target Current 0.585mA
Grid Voltage Change 0 to -3 from a TTL circuit.
-tony