From Eric

Contents 1 General information about CRT tubes 2 General diagram 3 The tubes 3.1 5LO38I russian tube 3.2 Chinese 8SJ31J tube 4 Other schematics 5 Other topics

General information about CRT tubes

Some explanations about the functioning of a CRT:

• http://www.cfp-radio.com/realisations/rea75/tv2pouces-01.html
• http://speakyssb.blogspot.com/2016/08/5lo38i-crt-test.html (5LO38I tube)
• https://www.electrical4u.com/cathode-ray-oscilloscope-cro/
• https://www.circuitstoday.com/crt-cathode-ray-tube
• https://www.aplustopper.com/cathode-ray-oscilloscope-construction-working/

General diagram

The most popular schematic, from Elextronixandmore, using a Hammond transformer. A kit can be bought at Catahoula Technologies. The schematic and the BOM are here.

Another one solid-state scope from Electronixandmore, without isolation. The voltages are the following:

 HV		350V	Anode Cap
 X1/X2/Y1/Y2	280V	Deflection plates
 A2		270V	Anode 2
 A1		-310V	Anode 1
 K		-665V	Cathode
 G1		-675V	Control Grid

Those values are fine for a 3BP1 tube.

The tubes

5LO38I russian tube

I have bought a russian 5LO38I tube on ebay.

The tube is delivered with a russian notice. Hopefully, someone has provided a german translation translation:

You can find several applications of the 5LO38I:

• http://danyk.cz/osc_en.html
• http://speakyssb.blogspot.com/2016/08/5lo38i-crt-test.html
• http://www.emartinka.cz/index.asp?IDKategorie=9&IDClanku=18&Akce=clanek
• http://www.labguysworld.com/ES_CRT_DEFLECTION.htm
• http://users.triera.net/zupanbra/osciloskop/Mali_osciloskop.html
• http://www.webx.dk/oz2cpu/clock-scope/scope.htm

Several schematics to generate the high-voltage power supplies:

• From http://danyk.cz/osc_en.html:

• From http://speakyssb.blogspot.com/2016/08/5lo38i-crt-test.html:

• From http://www.cfp-radio.com/realisations/rea75/tv2pouces-01.html

Chinese 8SJ31J tube

See Aliexpress (8SJ31 from GuangYi store (Aliexpress).

The datasheet can be found here : http://www.ges.cz/sheets/8/8sj31jv2.pdf

Other schematics

• https://www.webx.dk/oz2cpu/clock-scope/scope.htm
• http://www.jogis-roehrenbude.de/Leserbriefe/Scope-Clock/Scope-Clock.htm
• https://web.jfet.org/vclk/

• http://www.catahoulatech.com/index.php?product=KIT-0001|PCB
• http://www.sgitheach.org.uk/scope2.html
• http://ludens.cl/Electron/scope/scope.html
• https://www.eevblog.com/forum/projects/oscilloscope-under-construction/
• https://www.eevblog.com/forum/projects/2-inch-video-monitor/

Other topics

Oscilloscope music:

• https://oscilloscopemusic.com/software.php (a software to generate pictures using X-X modulation))

See also:

• The Dutchtronix oscilloscope clock