using oscilloscope crt+power supply

Thread Starter

uv147

Joined Dec 24, 2015
18
Hello,

A CRT as shown uses voltage on the deflection plates to move the beam.

In the posted schematic, you will see some controls like focus, astig and trace rotaion.
Those are NOT on the supply.

Bertus
but are the heater the cathode and the anode on the suply? and are they anough to just make the crt shoot a beam of electrons?
 
but are the heater the cathode and the anode on the suply?
--The equipment pointed to by the first (top) link might supply the cathode heater...
--The PSU is clearly intended to supply the 'final' and any post-acceleration 'anodes' --- as to other electrodes you'll need to contact the seller - or, better yet, locate technical literature on the instrument...

are they anough to just make the crt shoot a beam of electrons?
Of course - howbeit proper 'pre-acceleration' biases must be established.

Again, you are advised to use a TV CRT! -- Such will be both less complicated and better suited to your purposes!

Best regards
HP:)
 
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Dodgydave

Joined Jun 22, 2012
8,677
No the board on Ebay wont power the colour tv crt, it has higher Eht around 20 30Kv, and it has three heater guns, so will give you three dots, so will need the convergence coils to merge them,.
Your better using a monochrome crt.
 
No the board on Ebay wont power the colour tv crt, it has higher Eht around 20 30Kv, and it has three heater guns, so will give you three dots, so will need the convergence coils to merge them,.
Your better using a monochrome crt.
I thought OP was referring to the (linked) Ebay items (incl the CRTs)? -- Now I'm all confused:confused::confused::confused::eek:
That said, one can 'get away with' much lower EHT where only a point display is required:)
 

Thread Starter

uv147

Joined Dec 24, 2015
18
I attacking about the linked eBay item,s,
The problemm with TV is thatit'sthree colors and hard to take apart.
The scope cut is the easiest to manipulate.

--The equipment pointed to by the first (top) link might supply the cathode heater...
--The PSU is clearly intended to supply the 'final' and any post-acceleration 'anodes' --- as to other electrodes you'll need to contact the seller - or, better yet, locate technical literature on the instrument...


Of course - howbeit proper 'pre-acceleration' biases must be established.

Again, you are advised to use a TV CRT! -- Such will be both less complicated and better suited to your purposes!

Best regards
HP:)
What do you mean by pre acceleration biases?
 
@uv147

Please note that, should you chose to use a ('non-Trinitron') Colour CRT, single beam operation requires that you 'bias off' two of the three guns -- In any event, there will be no 'purity' - With a resultant polychromatic display 'dot'...

Best regards
HP
 
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The problemm with TV is thatit'sthree colors and hard to take apart.
The scope cut is the easiest to manipulate.
If a B&W TV CRT is unavailable you may use a CTV CRT but you'll need to electrically 'cut off' two of the 'guns'... (as noted in post #27)

...and hard to take apart
Again -- Acetone will greatly facilitate removal of all auxiliary components from the neck:)

What do you mean by pre acceleration biases?
G1 to Cathode, etc...

Respectfully, the fact that you need ask such a question strengthens the argument for use of a TV CRT:)

Best regards
HP:cool:
 
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Thread Starter

uv147

Joined Dec 24, 2015
18
I tried and was unable to disclnnect the two extra rays

By the way, can I connect the PSU directly to ac, AR a power supply my own using prototyping cables?

I am not taking apart the scope's CRT but rather not connecting the deflection plates to voltage is enough.
 
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recklessrog

Joined May 23, 2013
985
As you do not have a lot of experience with CRT's, a word of warning seems in order. All CRT's require a very high voltage on the final anode sometimes up to 30Kv. Even once you have turned the supply off, the final anode will remain charged due to the way the tube is constructed. A coating of graphite on the inside and outside form a capacitor and will remain charged for several hours.
The danger is not so much from electrocution, but from getting a shock that causes you to drop the tube and it implodes hurling large pieces of razor sharp glass at high velocity in all directions possibly causing serious injury to anyone close by.
You MUST safely discharge the tube before handling it. Google "discharge high voltage capacitors" on how to do this safely.
 

Thread Starter

uv147

Joined Dec 24, 2015
18
As you do not have a lot of experience with CRT's, a word of warning seems in order. All CRT's require a very high voltage on the final anode sometimes up to 30Kv. Even once you have turned the supply off, the final anode will remain charged due to the way the tube is constructed. A coating of graphite on the inside and outside form a capacitor and will remain charged for several hours.
The danger is not so much from electrocution, but from getting a shock that causes you to drop the tube and it implodes hurling large pieces of razor sharp glass at high velocity in all directions possibly causing serious injury to anyone close by.
You MUST safely discharge the tube before handling it. Google "discharge high voltage capacitors" on how to do this safely.
Thank you very much!

So can I connect the PSU to ac or my own power supply?
 

Dodgydave

Joined Jun 22, 2012
8,677
You need the psu that is designed for the scope board, it will need around 250V dc.

I get the impression you are out of your depth here with this scope obsession.
 
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Thread Starter

uv147

Joined Dec 24, 2015
18
You need the psu that is designed for the scope board, it will need around 250V dc.

I get the impression you are out of your depth here with this scope obsession.
You are totally correct! ;)
Anyway, thank you all for helping me,I really appreciate!
 
@uv147
Leaving the deflection plates floating is inadvisable! they should be tied together and placed at a potential approaching (but less than) the final/'post final' accelerating electrodes -- Please see the tube specifications for the correct anode vs DP EMF ratio.

Again, you're going about this the hard way! You need only search Ebay for a monochrome TV CRT of 1970 or later manufacture (such that magnetic and, hence, external, 'ion trap' magnet and focus coil are not required) -- Moreover, inasmuch as 2KV is sufficient to produce a 'spot', assembly of the accelerator PSU is a simple matter (IPOF you may, theoretically, 'get away with' less than 2kV in your application - however the electrostatic focus 'feature' may be insufficient below a few kV) -- Note also that the lower the accelerator EMF, the lower the required deflection current:)

All of which is to say: With a monochrome TV/Monitor CRT the 'hard work' is already 'done for you' sans unneeded features to 'get in your way':)

Best regards
HP
 

Thread Starter

uv147

Joined Dec 24, 2015
18
@uv147
Leaving the deflection plates floating is inadvisable! they should be tied together and placed at a potential approaching (but less than) the final/'post final' accelerating electrodes -- Please see the tube specifications for the correct anode vs DP EMF ratio.

Again, you're going about this the hard way! You need only search Ebay for a monochrome TV CRT of 1970 or later manufacture (such that magnetic and, hence, external, 'ion trap' magnet and focus coil are not required) -- Moreover, inasmuch as 2KV is sufficient to produce a 'spot', assembly of the accelerator PSU is a simple matter (IPOF you may, theoretically, 'get away with' less than 2kV in your application - however the electrostatic focus 'feature' may be insufficient below a few kV) -- Note also that the lower the accelerator EMF, the lower the required deflection current:)

All of which is to say: With a monochrome TV/Monitor CRT the 'hard work' is already 'done for you' sans unneeded features to 'get in your way':)

Best regards
HP

Ordering a TV is a bit of a problem because I need it to arrive Israel in less then a week, and I on,g found these two CRT's from Israeli sellers
 

Thread Starter

uv147

Joined Dec 24, 2015
18
My suggestion was that you acquire a TV CRT only -- you don't require the entire TV receiver:)

Best regards
HP:)
we did try to disassemble a tv to get the crt only, an engineer who works with us said it was impossible to disconnect two electron beams.
and the cope's crts are the only ones that are in israel.
 
we did try to disassemble a tv to get the crt only

And again:

[if] the deflection yoke is chemically bonded to the neck/bulb, please be advised that it may readily be removed via application of ketone solvents (e.g. acetone)
Acetone will greatly facilitate removal of all auxiliary components from the neck:)

an engineer who works with us said it was impossible to disconnect two electron beams.
Either:
1)
He/She misunderstood your question
--OR--
2)
You misunderstood his/her answer
--OR--
3)
He/She is an ignoramus requisite of summary dismissal! I truly despair what occasionally passes for 'engineer' as of late!:rolleyes:

But to the point:
Please note that, should you chose to use a ('non-Trinitron') Colour CRT, single beam operation requires that you 'bias off' two of the three guns -- In any event, there will be no 'purity' - With a resultant polychromatic display 'dot'...

I need it to arrive Israel in less then a week
You will please forgive the observation that, as one having little expertise in this area, you have left matters rather late...:(

Best regards
HP
 
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Thread Starter

uv147

Joined Dec 24, 2015
18
Also the problem with a monochrome TV is that the ray is being constantly scanned ans as much as I know the deflection yokes are part of the hv circuit of the cathode/anode
 
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