This is how the old AC/DC television & radio sets worked. Originally, tube filament voltages were standardized at 6.3vac. You would see a filament transformer in the set that would run the filaments (in parallel).. later, some bright spark figured out that if you run all of the filaments in series in the entire set (+ a resistor) you can get up to 110vac. Whenever you see a tube with a 31v or 24v filament voltage, that is what those tubes were designed for. In an ironic twist, hams have learned that the more obscure filament voltage versions of the original parts are oftentimes less rare (less expensive). With the addition of a special filament transformer specific to the particular tube, they can be used as drop-in replacements.
-Adam On Sat, Jan 21, 2012 at 3:01 AM, fixitsan <[email protected]> wrote: > > I've been planning on doing something about losing the energy > absorbing resistors I presently use to hold the filament voltage at > 2.45V on the IV-17 Smartsocket > > Here's an idea which might be of interest. Putting two filaments in > series produces a requirement for 4.9V. I have a 5v supply and if i > apply that to the filaments i am in the ballpark. Except, there is > quite a large gradient across 2 tubes. > > Apologies if this has already been suggested, but I can't see much of > a problem with connecting the 2 series filaments to the output of an H- > bridge being switched in both directions at a few hundred Hertz. > Although I can use a microcontroller output to drive the H-bridge, any > switching signal could be used. No need for AC or a transformer like > this. > > Chris > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To post to this group, send an email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/neonixie-l?hl=en-GB. > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
