DIY scope

[Grant Richter]

Your best bet is to use simple resistor voltage
dividers. These will need to be high value resistors.

I have a schematic from the 1936 ARRL handbook
for a DIY scope. With a 1000 volt supply the cathode
is held at 58 volts, the G1 grid goes form 0 to 58
volts to vary the beam intensity. The A1 focus
grid varies from 120 to 290 volts. A2 grids and two
deflection plates are held at 900 volts. The other
two defection plates have 1 meg pots that vary
the voltage between 800 and 1000 volts for X-Y
centering. There are 1 meg resistors in series with
the pot wipers and the signal is capacitively
coupled directly to the plate.

No tube type is specified. Description is any
2 to 5 inch electrostatic deflection CRT.

The one meg pots have more than 200 volts
across them, and have to have long plastic
shafts for insulation.

You better know what the hell you are doing
because 800-1000 volts is LETHAL and
will kill you before you know you are dead.

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> From: Rene Schmitz <uzs159 at uni-bonn.de>
> To: synth-diy at mailhost.bpa.nl
> Subject: DIY scope
> Date: Tuesday, January 11, 2000 12:37 PM
> 
> Hi all!
> 
> Recently I acquired two 30mm oscilloscope tubes. 
> (Made in GDR, 1971, the warranty card was still in the box ;-)
> 
> Now here is the synth content:
> I toy with the idea makeing a small display for waveforms.  
> I think I don't need a timebase, X-Y operation will 
> suffice, maybe a luminance input. 
> I figured out the pinout and heater voltage, and I've been able to get an
> unfocussed spot on the screen. 
> 
> Now my questions are:
>  
> How do I best get the required voltages? (The tube has cathode, 
> luminance electrode (g1), a focussing electrode (g3) and the anode. 
> Two deflection caps.)  
> A small switcher perhaps? Can I get away with a single supply of 
> say 800V and make a tap for the focussing electrode? How much current 
> will the anode and the focussing electrode draw? Do I have to ground the 
> anode, or the cathode?  
> 
> Oh, and if somebody has any informations about a B4S2 crt, let me know.
>  
> Bye
>  René
> 
> opinionsexpressedher   | uzs159 at uni-bonn.de
> einarethatofmyemploy   | http://www.uni-bonn.de/~uzs159
> erandnotofmyself....   | http://members.xoom.com/Rene_Schmitz  
>                                    
>                                    
> 
>