Open Felthry opened 4 years ago
gosh-darn
commented
4 years ago Oh yes! I was considering to simulate an old 1933 portable radio, but alas, it used space charge tetrodes. I think this would be a wonderful addition, especially considering a triode is already included—why not have more to complete the collection?
pfalstad
commented
4 years ago From my limited research on a space charge tetrode, it seems that the extra grid is supposed to have a fixed voltage applied to it which improves the characteristics. So you could probably ignore the space charge grid and use a triode with different parameters (not sure what those would be).
gosh-darn
commented
4 years ago From my limited research on a space charge tetrode, it seems that the extra grid is supposed to have a fixed voltage applied to it which improves the characteristics. So you could probably ignore the space charge grid and use a triode with different parameters (not sure what those would be).
Huh, that sure is interesting … when I look at the schematic for the radio, I do indeed see the space charge grid simply connected to +15 volts, so it seems you are right! I know very little about the operation of vacuum tubes personally so I will definitively have to take another look at this :-)
Here is a short description of the radio in Norwegian (I did a quick English translation further down in the comment) as well as the schematic if you should be interested:
It is unfortunately missing a few values and units, but those familiar with radio recievers might find it intuitive nonetheless.
Roughly translated to English, the (Norwegian) description reads: «Tommeliten was the first appliance that Tandberg’s Radio Factory sent out. I was manufactured in 1933 and cost, tubes and headphones included, 99 kroner (90 + stamp 9).
Tommeliten is designed for use on boats, in cabins, and other places where electricity is unavailable. It has therefore been put into consideration that it should be quite portable and consume minimal power. It draws 0.14 amps of filament current from a 1.5 volt cell, and 4 milliamps from a 15 volt battery. The tubes in question, Philips A 141 or Tungsram DG 107, are special double grid tubes (space charge grid) for a low anode voltage.
Tommeliten is a single circuit, detector receiver with feedback, and has a single low frequency amplification stage following the detector. It has two wave bands, long wave and medium wave. The coils for the tuning circuit are done as large flat coils and can perform the service of a frame antenna. The radio does in other words not require an antenna for the local station.
On the front panel, there are to the very left, three sockets, the bottom one is ground, the middle is for connecting a short antenna and the top one is for a long antenna. The large knob with a dial controls the tuning capacitor C2. Of the two smaller knobs, the top one is the feedback (C3), and the bottom one is combined power and band selector switch with three positions: L for long wave, K for medium wave, og the middle position which turns the radio off. To the very right are two sockets for the headphones.»
smtaheri
commented
3 years ago that would be really nice to have, I wanted to simulate a simple electron beam gun with simple HV supply.
It'd be nice to be able to simulate slightly more advanced vacuum tube circuits, though I imagine this would be very low priority as they aren't exactly the kind of thing that is very relevant nowadays. In particular, I think the following tubes would be nice to have simulated:
Tubes that simulate the heater as well (either directly or indirectly heated) would be interesting, but probably not worth the effort. Likewise for a pentagrid converter; interesting, possibly useful if one wanted to simulate an all-american five radio, but probably more work than it's worth to include. Really, all of these suggestions may be more work than they're worth, given how utterly irrelevant vacuum tubes are in modern times! I just think they're neat.