[sdiy] Integral scope on VCO

[Thomas Dunker]

On Wed, 14 Apr 2004, Magnus Danielson wrote:

> CRTs don't require huge current really, but the electron beam is indeed a
> current which needs to be balanced, or it will pull down the voltage. The 2AP1
> tube is probably quite close to what you got

 Yes, very close, it seems.

> here, but a friend has the full Philips suite of databooks) and it is fairly
> easy to hook things up. My sources here are from.... HRM! 1945 and 1948!

 DH3-91 was apparently issued around 1958. There's some specs here:

http://www.tubecollector.org/dh3-91.htm
(color photos too - have a look at that pup!)

and Philips spec sheets here:

http://w1.871.telia.com/~u87149906/crts/dh3-91.htm

> The traditional way of generating these voltages is to span up the 1-2 kV
> needed and divide down and burn of the intermediary effect. A more modern way
> might be to do a few small switch-supplies which one regulates to the target
> voltage. They shouldn't need to be very complex really. Hmm... interesting
> concept.

 That's my choices, basically... I know it would take *me* a fraction of
the time (and cash, logistics etc.) to whip together a linear old
fashioned supply with a divider, and if I can afford to use that kind of space
in there it's okay.
 It ought to be possible, as the front panel for this module is going to
be 216x125mm and max depth is about 130mm. It would get a little heavy but
that may be okay. I need 6.3V at 550mA for the heater anyway and I can get
that from the same transformer (got a fairly small one with 350V-0-350V,
6.3V and 5VAC secondaries that I can use).

 I'm really more concerned about all the pots and controls I'll have to
squeeze in on the front panel to pull off this nutty scheme. Behind the
panel at least there's three dimensions to pack full of electronics...

 Got to sleep on it...

Thomas