Tuesday, August 30, 2016

5LO38I CRT test


Having this CRT for some time, never tested it, so last weekend with the new soldering iron was the right time for it.




Honestly can't remember for which project I got it, in any case it will be useful in the future.. so I hope,

Power supply was based on this diagram:



From this site:
http://danyk.cz/osc.html

Added some discharge resistors so it unloads faster, even so it would take around 10m to go to 0v.

The brightness and focus control diagram:


From this reference:
http://www.emartinka.cz/index.asp?IDKategorie=9&IDClanku=18&Akce=clanek

Didn't used any circuit for testing the deflection but touching with a long wire is enough to cause deflection, so it's working also.

I might need to tune the controls and power supply since the dot is a little too big, don't know exactly what is the relation between focus voltage differential from the electron gun and the dot size, sure it's related.



The box it's standard soap box in plastic so I'm not tempted to touch the circuit while it's operating. If I finish the project it will be for sure placed in a more attractive enclosure.

Internaly:

Didn't had an isolation transformer 230/230 so used an 230/12 connect to a 15/230v. I had my shares of electric shock's and will no risk touching a rectified point directly to mains.

The controls:
The rectifier board:

upside down on the box so the electrons can drop easily...

And the connection to the CRT pins, this is the best way found since I had no holder for it, no mess with solder and quite isolated:


For reference, additional sites with more information case you want to build  a scope based on this CRT tube:

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

The technical details of the tube:



Have a nice day!


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