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CRT Oscilloscope

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Aily Sajjad

New Member
Hi,

I have a small TV. I made a little work on the CRT defelction yoke and added some circuits and converted it to an oscilloscope - working on low frequencies. Is it possible to use the same CRT for viewing high frequency signals? (in the Mhz range).

What are the frequency limitations of CRTs with magnetic deflection yokes? Can anybody help me?

Aily

**If you have started - Its done***
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Aily Sajjad said:
Hi,

I have a small TV. I made a little work on the CRT defelction yoke and added some circuits and converted it to an oscilloscope - working on low frequencies. Is it possible to use the same CRT for viewing high frequency signals? (in the Mhz range).

No, not in that way.

What are the frequency limitations of CRTs with magnetic deflection yokes?

EXTREMELY limited, the deflection coils are only designed to work over a small frequency range, it's useless as a scope.
 

Aily Sajjad

New Member
What is the reason for this? behaviour of inductance at high frequencies? or any thing else.

Can you suggest some idea based upon which one can build a cheap oscilloscope?

now getting informal...

hey Nigel you are my ideal.. remember me? you are the martial art guy? isnt it?


Aily
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Aily Sajjad said:
What is the reason for this? behaviour of inductance at high frequencies? or any thing else.

Yes, they are highly non linear, and frequency sensitive - you might be able to get low audio frequencies out of it, but not with any accuracy.

Can you suggest some idea based upon which one can build a cheap oscilloscope?

Buy a second hand scope! - there's really no cheaper way. To use a TV or computer you really need all the elctronics of a digital storage scope, and use the TV/Computer purely as a display device.

now getting informal...

hey Nigel you are my ideal.. remember me? you are the martial art guy? isnt it?

Yes, I'm the Ju Jitsu guy!.
 

Sceadwian

Banned
I bought a 500khz dual trace scope in working condition on e-bay for 30 bucks (half of that was shipping) You can do at least that good for 100 bucks or less. that's cheap for a scope.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Sceadwian said:
I bought a 500khz dual trace scope in working condition on e-bay for 30 bucks (half of that was shipping) You can do at least that good for 100 bucks or less. that's cheap for a scope.

Are you sure you mean 500KHz?, that's awfully low for a scope?.
 

Sceadwian

Banned
Yes, I mean 500khz. HP 1200B It's fine for a lot of simple signal work, makes a decent high speed multi-meter if nothing else. the time base goes down to 5 seconds a division so it can also be used to trace very slow moving waveforms (though I haven't found the need yet) Just do a google search for them, I think a hollywood set must have sold a lot of them they used for background eyecandy because there's a decent number of them out there. If you've ever seen the show Stargate and you pay attention to the backdrops in their medical/scientific labs they have enough 50 year old oscilliscope to sink the titanic =>
 

on1aag

New Member
500 kHz scope.

I've got a similar scope, a hp1202B. I use it to service microphone
preamplifiers in transmitters. It also has a 50 kHz low-pass filter and
the 100 µV/div. vertical sensitivity sometimes really comes in handy.
It is definitely not for sale, there's simply no (affordable) alternative
for this scope. :p

on1aag.
 
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