Actions
Forum Thread Details
  • Replies 2 replies
  • Subscribers 42 subscribers
  • Views 279 views
  • Users 0 members are here
Related

building an CRO

Former Member

Dear Sir(Or control freak(you said you wont mind in the PCB etching tutorial :remember))

I looked to buy an CRO but they were expensive so i request you to design a circuit that we can connect to a cathode ray tube from an old TV and can convert the od TV into and CRO.

Thanks in advance.

Yours faithfull;

Nobert22

  • That'll be a good trick  - the tubes in TVs are very different from those in scopes. TV tubes use magnetic coils for beam deflection which are slow but can bend a high energy electron beam through a wide angle, CRO tubes use electrostatic deflection which is fast but can't exert as much force on the electron beam - which is why CRO tubes are much longer than TV tubes for a given screen size and much less bright.

     

    The (only?)  way to use a TV screen as  a scope is to use it as a display for  a micro or computer and make a digital scope - so it needs to be  a working TV.

     

    If you have a computer, even an RPi is good enough, you can buy a cheap digital scope add on - or even make one (not very fast) from a microcontroller dev. board.

     

    MK

  • in reply to michaelkellett

    Another advantage to magnetic deflection for TV is that it was found to be more amenable to a ramping signal while capacitive  deflection suited random raster better.  They made a few tubes with capacitive deflection for one axis and magnetic deflection on the other.  This was inconvenient to manufacture as both sets of deflection apparatus had to be in the one place, as the vectors are 90 degrees apart between magnetic and charge field deflection.  I am going to do some work with CROs because I want to experiment with slow phosphor.  The old oscilloscopes that I obtained do not conform to modern safety standards, I will have to reconstruct them from the ground up.  I'm yammering.  MK has got you covered.  If you obtain a PC oscilloscope card, make sure that it is compatible with your OS.  Bon Chance!!