[sdiy] bottle ladder filter

[Magnus Danielson]

From: Tim Ressel <madhun2001 at yahoo.com>
Subject: Re: [sdiy] bottle ladder filter
Date: Sun, 21 Apr 2002 01:39:22 -0700 (PDT)

> Yo,
> --- Peter M Blackett
> <dragonservicing at success4business.com> wrote:
> > Dear Tim,
> > that seems like a most interesting project !
> > but I think you may need more that the 100 volts ht
> > for the circuit to
> > work correctly.
> > But I know that means using a more complex heater
> > supply as I think the
> > heater cathode insulation of the tubes [valves ] 
> > may only be able to
> > stand 100 volts or so .
> > so you would need at least two heater windings ,not
> > at ground potential.
> 
> Ah, I see you never sleep either. Or are you across
> the pond?  Anyhow, yeah, I think you may be right
> about the B+. The max signal level is quite low.
> Boosting the B+ may help. As for fancy filament
> circuits, the first attempt will consist of cheap
> little transformers (one per tube??). Once I know the
> final B+ value, I'll deal with final heater details.

I think that you could use simple transformers. I also think it would
be wise to wire the secondary sides to a bias network, so that they
gets "guided" to the right DC level.

Maybe one should swap the cathode and the grid for better peformance?

> In the meantime, its lots of fun to pretend I know
> what I'm doing with all this valve stuff. I'm bidding
> on a copy of the Radiotron Designer's Handbook. That
> should help. Having worked with tubes in my youth, I
> know a few things. Like don't work on HV when you're
> groggy from lack of sleep.

Well, that's certainly a good lesson. Did you learn anything similar
relating to alcohol? ;O)

> Gosh golly this is fun!

Hehe... ;O)

Cheers,
Magnus