Err, no... There is this witch-hunt against capacitors, but other components are never considered There are several supplies derrived from the flyback transformer. Let's take as an example the Ball Brothers VT100 monitor on page 43 of the printset on bitsavers. There is a -120V line, used for the control grid (g1), produced from the primary side of the flyback by CR110 and C117. I think if this failed it wouldn't damage the flyback, though There is a +32V supply for the video amplifier, produced by CR114 and C121 A 400V supply for the the first and focus anodes (OK, g2 and g3 across the Pond [1]) -- CR113 and C120. If either of those play up in can cause the flyback to overheat, The 11.5kV final anode voltage is produced by CR1 and smoothed by the capacitance of the CRT. I think CR1 is integral with the flyback transformer though. [1] In the UK we call all CRT elecrodes after the control grid (first grid) 'anodes' which makes sense as they are run +ve wrt the cathode. In the states, everything between the cathode and final anode (the aquadag coating on the CRT flare running at 10kV or more) is a 'grid'. Now something has just struck me. The adjusment for the first anode, if present (it isn't in this VT100) is known as the 'screen' control. What I do not know is if it's called that because it controls the overall brightness of the CRT screen, or because it sets the voltage on what is called G2 across the Pond, and which would be the screen grid of a tetrode or pentode. Does anyone know the reason? -tony

The second. A Tetrode over here has 2 grids (control grid and screen grid [1]) and one anode. A pentode has 3 grids (control, screen, supressor) [1] An old name for a tetrode or pentode over here is a 'Screen grid valve' Some early valves had type codes which clearly came from this For example there was a 'AC/SG' which was an indirectly heated (the 'AC' part, meaning the heater could run on AC) tetrode (the 'SG' part). I have an old Cossor MVS/PEN valve. That stands for 'Metalised' (meaning there is a conductive coating on the outside of the glass envelope for shielding), Variable Mu (non-linear, so amplification depends on grid bias) Screengrid (a tetrode or pentode) and the 'PEN' part means it really is a Pentode. Also note that we use the term 'valve' for diodes, triodes, etc, but 'tube' for CRTs, nixie tubes, dekatrons, voltage stabilisers, probably trochotrons, etc. There seems to be no obvious reason for what is a 'valve' and what is a 'tube'. -tony paul

Possibly. But diodes are normally called 'valves' over here, in fact I think the term 'valve' came from the fact that a diode acts like the one-way valve, say on a tyre. And not necessarily vacuum devices. Thyratrons (gas filled triodes) are 'valves'. So is the infernal 0Z4 :-). But not voltage stabilisers. I am trying to think what we call tuning indicators -- magic eyes and the like. Probably valves (even though they don't control anything and are display devices). I wonder if they were ever used in early computers. Dekatrons were, both in the Harwell Dekatron machine, and in some Anita calculators. But I've only come across trochotrons in digital voltmeters and the like. -tony