Klaas's magnetic deflection amplifier circuit

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Re: Klaas's magnetic deflection amplifier circuit

Postby Harry Dalek » Tue Nov 28, 2017 11:20 pm

Klaas Robers wrote:Why are there 4 wires in parallel?


i don't know if they are just yet klaas as only took left or a right reading apart from trying the 1 pin and 8 when shorting 4 and 5 to get 8 ohms .
I will test right side to left side and see what i get ..i under stand what your thinking as why all one side is shorted it does make sense that they have to be connected left and right side coils i will see tomorrow if i can give some numbers

In a normal TV the horizontal deflection is running a saw tooth of 16 kHz. Then, especially during the fast fly back, there are such high frequencies running, that the current has no time to run deeper in copper wires. So they run only in the surface of the wire. This is called the "Skin Effect".

The horizontal deflection coil needs to have a low resistance. Normally this is obtained by a thick wire. But then, due to the skin effect, the current runs only in the outer part of the wire, so the copper is only partly used.


OH that's the reason for the wire size difference ! had not come across that or explained before .

This can be overcome by using several mutually insulated wires in parallel. At both ends they are soldered together. That is why the H-coil is made up of 4 wires in parallel. They all have the same length, so they should have the same resistance after you disconnected them all, at both ends. Then you should find 4 wires that are fully insulated from each other.
[/quote]

When i test left to right side only tomorrow might work out the wiring better as left to right visa versa must be going to either side to the lugs
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Re: Klaas's magnetic deflection amplifier circuit

Postby Harry Dalek » Wed Nov 29, 2017 3:23 pm

Ok I have tested both sides of the 8 wires of this yoke coil .

Its pretty much each one of the 4 wires left or right side connects to 2 of the other side of the yoke coil wires .
So giving 2 ohm reading on each of the 2 wires ..
If that makes sense !
I made some connectors for the 8 wires not pretty but saves the wires of the yoke being broken and testing different wiring combinations .
Attachments
IMG_0319.JPG
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Re: Klaas's magnetic deflection amplifier circuit

Postby Klaas Robers » Wed Nov 29, 2017 8:01 pm

Clear photo's Harry. It is good that you soldered all ends to pins. Now lets start at the beginning.

Please let me know, if you measure the resistance from pin 1 to pin 2, if you measure OL (open line). If you do not touch the pins 5 to 8, you should not measure any resistance (so OL ore Open Line) from:
1 to 2,
1 to 3,
1 to 4,
2 to 3,
2 to 4,
3 to 4.
Then all 4 wires through the coils are insulated.
If not, wires are touching each other somewhere. Then is is difficult, or even impossible, to connect everything in series.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Harry Dalek » Wed Nov 29, 2017 9:27 pm

Klaas Robers wrote:Clear photo's Harry. It is good that you soldered all ends to pins. Now lets start at the beginning.

Please let me know, if you measure the resistance from pin 1 to pin 2, if you measure OL (open line). If you do not touch the pins 5 to 8, you should not measure any resistance (so OL ore Open Line) from:
1 to 2,
1 to 3,
1 to 4,
2 to 3,
2 to 4,
3 to 4.
Then all 4 wires through the coils are insulated.
If not, wires are touching each other somewhere. Then is is difficult, or even impossible, to connect everything in series.


Ok ....i soldered my wires 4 wires either side but may not be correct from last posts ...but as they are now these are the readings with the pins their soldered on hope it makes sense ...last reading is 0.5 ohm the odd one out ? one meter had trouble here on this low reading the right reading seemed to change every test but multimeters were pretty much same 0.5 ohm
I tested with 3 meters one was showing 2 ohm and other 2 meters showing 1.7 1.8 ohm so went with those readings here...

Pins multimeter resistance reading left and inductance resistance meter right
1 to 2 n/c
1 to 3 n/c
1 to 4 n/c
1 to 5 n/c
1 to 6 n/c
1 to 7 1.8 ohm 1.7 ohm 0.23mH
1 to 8 n/c
2 to 3 3.4 ohm only showing resistance 4.0 ohm
2 to 4 n/c
2 to 5 2.0 ohm 1.7ohm 0.24mH
2 to 6 n/c
2 to 7 n/c
2 to 8 1.8 ohm 1.7ohm 0.24mh
3 to 4 n/c
3 to 5 1.8 ohm 1.7 ohm 0.24mH
3 to 6 n/c
3 to 7n/c
3 to 8 2.0 ohm 2.4ohm 0.24mH
4 to 5 n/c
4 to 6 1.8 ohm 1.7ohm 0.23mH
4 to 7n/c
4 to 8 n/c
5 to 6 n/c
5 to 7 n/c
5 to 8 0.5 0hm 0.24 ohm only showing resistance
Edit ....i was now looking into putting the coils in series i would think the windings have to go the right way not hooking them up one forward winding other back the front such ...but a quick look at just a resistance increase shorting pins 1 and 2 and taking a reading at pins 3 and 7 now this is a increase to 6.0 ohm ...i think the long wire i was using the shorting wire adds a bit of resistance to this or it should add up a bit lower bit over 5 ohm.
Klaas your Horizontal coil was 5 ohm do you think its needed to use the rest of the coils ? i am thinking since your circuit H is 5 ohm and V is 10 ohm it seems logical to copy that if possible .
I was testing deflection amp one and 2 one i think the first input transistor is faulty again its got a higher positive voltage on the collector does not seem to be working i can see the difference to deflection amplifier 2 which is working measuring testing its input transistor ...try a replacement tomorrow.
Attachments
IMG_0323.JPG
Last edited by Harry Dalek on Thu Nov 30, 2017 7:30 pm, edited 1 time in total.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Klaas Robers » Thu Nov 30, 2017 7:20 pm

Ok, this makes sense. I concluded:

1 o-----COIL-----o 7

2 o-----COIL-----o 5 ----+

3 o-----COIL-----o 8 ----+

4 o-----COIL-----o 6

Each coil has an insuctance of 0,24mH and an resistance of 2 ohm.
And there is an parasitic short of pin 5 to 8. May be that the wires just touch each other at a point where they are just made blank.

You can do this:
Connect 2 to 7
Connect 3 to 6
Connect 5 to 8 (they are already connected, but still do it. I don't like "parasitic")
Connect 1 to 4.

Now 1-4 is one end of your coil and 5-8 is the other end. The resistance will be 2 ohm, the inductance, I don't know. It can be 5mH but it can also be 20 mH.

Try this first. Then, if you can find the parasitic short from 5 to 8 and if you can eliminate it, you can also put all in series and end up with 8 ohm.

You see indeed that the current runs always from left to right (or reverse). That is how it should be. That is also the reason that you measure 4 ohm and no inductance from 2 to 3. Then the resistances are in series and the inductances in opposite directions.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Klaas Robers » Thu Nov 30, 2017 7:32 pm

Harry, it was quite easy to make the winding-list after your valuable measurements.

- I knew: there are 4 coil windings,
- so I drew 4 coils with each two ends.
- Then I started your list:
- 1 to 7
- 2 to 5
- and then skipping the other measurements of 2 to 3 and 2 to 8
- 3 to 8, because 5 was already in use,
- and 4 to 6.

It is still possible that, when you find the parasitic connection between 5 and 8, that it is:
- 2 to 8 and
- 3 to 5.

I think that your measuring wires have a resistance of 0.5 ohm, or it is the resistance of the contacts. 5 to 8 will be much lower than 0.5 ohm....... Try to measure e.g. 5 to 5. It will be 0.5 ohm.

Keep me informed.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Harry Dalek » Thu Nov 30, 2017 7:43 pm

Klaas Robers wrote:Ok, this makes sense. I concluded:

1 o-----COIL-----o 7

2 o-----COIL-----o 5 ----+

3 o-----COIL-----o 8 ----+

4 o-----COIL-----o 6

Each coil has an insuctance of 0,24mH and an resistance of 2 ohm.
And there is an parasitic short of pin 5 to 8. May be that the wires just touch each other at a point where they are just made blank.

You can do this:
Connect 2 to 7
Connect 3 to 6
Connect 5 to 8 (they are already connected, but still do it. I don't like "parasitic")
Connect 1 to 4.

Now 1-4 is one end of your coil and 5-8 is the other end. The resistance will be 2 ohm, the inductance, I don't know. It can be 5mH but it can also be 20 mH.

Try this first. Then, if you can find the parasitic short from 5 to 8 and if you can eliminate it, you can also put all in series and end up with 8 ohm.

You see indeed that the current runs always from left to right (or reverse). That is how it should be. That is also the reason that you measure 4 ohm and no inductance from 2 to 3. Then the resistances are in series and the inductances in opposite directions.


Thanks for looking Klass ! i am not sure i could have worked this out may be trial and error but i am grateful i can use your mind !
Yes the 5 and 8 reading had me wondering !
When i have some more time later tonight i will hook it up to your instructions .
With the go i had at 6 ohm got a line about an inch but the line was thin one end thicker other ...i connected another pin to it it was thin all along again but any way will wire it up your way and see .
I mentioned last post i have to repair deflection amp ones input transistor again its gone faulty higher positive voltage on the collector ...not as bad as the first time but looks like its a goner .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Klaas Robers » Thu Nov 30, 2017 8:42 pm

Harry, the first time you had a negative voltage at the collector, almost the voltage of the emitter (- 0.7 volt).
The collector should be about + 0.7 volt and the base voltage about 0 volts.

In fact it is strange for the input transistor to "die". It has all high resistor values,
- to the base 10k and 6k8
- to the collector 12k
- to the emitter 2k7
Currents can never be large enough to destroy the transistor.

I don't understand this. Oh, the voltage on the collector CANNOT be higher than 0.7 volt. If it is higher than +1 volt the 548 is destroyed. This transistor has a base-emitter diode to ground. The voltage over that diode is max. 0.7 volt to 1 volt. Otherwise that transistor is destroyed. Don't know how.

I saw in the circuit diagram that there is a capacitor 15 nF from base to emitter. This is to prevent oscillation. You have connected that capacitors, didn't you?
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Re: Klaas's magnetic deflection amplifier circuit

Postby Harry Dalek » Thu Nov 30, 2017 11:33 pm

[quote="Klaas Robers"
]Harry, the first time you had a negative voltage at the collector, almost the voltage of the emitter (- 0.7 volt).
The collector should be about + 0.7 volt and the base voltage about 0 volts.


i started to look into this why deflection amp 1 has gone bust ..i had to stop after some testing tonight as i have got my self in a muddle ..
I found at first the wire from the feed back resistor had come loose reason for the high collector voltage and soldered it back reading went into the negative -0.57 range ...i looked into why mine is negative on the first deflection amplifier and positive on the second .
i found increasing the feed back resistor with a trimmer for testing here to 37k brings the collector voltage into the positive 0.7 ..as you have shown me .
Checking with my scope inputting a 400 hz sawtooth to the 6.8k input resistor and scope on the collector of the first transistor there's a square wave ...i checked my second deflection amp and same result a square wave out on the first trany collector it is deflecting a small line on the monitor screen but a scope reading on the ouput transistor collectors shows its a square wave as well ... on the first deflection amp i am getting nothing on the collectors

only thing i have changed of the circuit since last test is add the 10uf caps to the positive and negative power rails to ground ...


In fact it is strange for the input transistor to "die". It has all high resistor values,
- to the base 10k and 6k8
- to the collector 12k
- to the emitter 2k7
Currents can never be large enough to destroy the transistor.


it does not seem like it was now just the feed back resistor wire was disconnected my mistake on this .

I don't understand this. Oh, the voltage on the collector CANNOT be higher than 0.7 volt. If it is higher than +1 volt the 548 is destroyed. This transistor has a base-emitter diode to ground. The voltage over that diode is max. 0.7 volt to 1 volt. Otherwise that transistor is destroyed. Don't know how.

I saw in the circuit diagram that there is a capacitor 15 nF from base to emitter. This is to prevent oscillation. You have connected that capacitors, didn't you?


So klaas its not your circuit
Yes the 15nf is connected .
i should be getting a sawtooth at the collector of input transistor and why deflection amp 1 not working after the first transistor ...sometimes best to rest and have a fresh look next day :roll:
Last edited by Harry Dalek on Fri Dec 01, 2017 7:58 am, edited 1 time in total.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Klaas Robers » Fri Dec 01, 2017 12:43 am

Harry, a somewhat rounded square wave at the collector is not unusual, when the 2k2 trimming resistor is at zero ohm. The shape of the wave forms is not so important, the only that should be a saw tooth is the voltage at your 8 ohm resistor. That should be the same saw tooth as the input saw tooth but upside down inverted and 50% larger.

That is the test to see whether the circuit works correctly.

For the funtioning of a transistor you should realise that a transistor works on CURRENTS, not Voltages. It is far more difficult to observe currents rather than voltages. And as transistors are made up all of diodes, the voltage waveforms are strongly different from the current waveforms. An oscilloscope gives only very rough indications.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Harry Dalek » Fri Dec 01, 2017 8:18 pm

Klaas Robers wrote:Harry, a somewhat rounded square wave at the collector is not unusual, when the 2k2 trimming resistor is at zero ohm.


OK
Its still a bit of a messy i might have a bad grounding some where .
But its not to bad after the first input transistor on its collector on both deflection amplifiers no longer a square wave back to some thing that looks like a sawtooth i noticed btw it looked better closer to the input waveform on power being turned off and is dropping off .

I think there is a bit of a shake to the waveform i need to double check this .

The shape of the wave forms is not so important, the only that should be a saw tooth is the voltage at your 8 ohm resistor. That should be the same saw tooth as the input saw tooth but upside down inverted and 50% larger.That is the test to see whether the circuit works correctly.


Well in the horizontal it looks larger a bit....but it is again a messy waveform.... test points second last photo the power transistor collectors and last at the low ohm resistor ...i have a way to go on this ,i had it not to bad a while back looks like i have to claw my way back so some better results

For the funtioning of a transistor you should realise that a transistor works on CURRENTS, not Voltages. It is far more difficult to observe currents rather than voltages. And as transistors are made up all of diodes, the voltage waveforms are strongly different from the current waveforms. An oscilloscope gives only very rough indications.


Ok Klass on testing one amplifier on one yoke coil i can see some deflection happening with a vertical or horizontal sawtooth input so the current wave form must be better than what i am seeing .

I am not to sure the way i have went making the 2 amplifiers on the same board sharing power rails and such is the way to go or i should of made it easier to separate the power rails ground .
it is not the best way to go on duplicate circuits like this with them in parallel powered on same time
Does make fault finding harder and not knowing if the other circuit in parallel is effecting the results of the other .
I should of made just one got it going then make the other ...a life lesson ..
Any case i will try again or repair fault find .
Attachments
IMG_0324.JPG
input to 6.8k
IMG_0328.JPG
collector of transistor 1 deflection amp 1
IMG_0329.JPG
collector of transistor 1 deflection amp 2
IMG_0331.JPG
out of the collectors power transistors
IMG_0332.JPG
low ohm resistor
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Re: Klaas's magnetic deflection amplifier circuit

Postby Klaas Robers » Fri Dec 01, 2017 9:37 pm

Harry, look on your +12 and -12 volt lines. I expect that they are not +12 and -12 all the scan time. Then you need a better power supply, one (two) that is better stabilized. At least for up to 1A. The current of the coil is not low. Under all circumstances they should keep their voltage. That may also clear up the cross talk of the two saw teeth and the messy pictures that you get.

good luck
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Re: Klaas's magnetic deflection amplifier circuit

Postby Robonz » Sat Dec 02, 2017 11:36 am

Those missing decoupling capacitors won't be helping either.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Harry Dalek » Sat Dec 02, 2017 2:48 pm

Robonz wrote:Those missing decoupling capacitors won't be helping either.


No that's with them keith ...i worked on it to day i have found its over loading on the dual 12 volt supply seems to high ,i dropped the voltage swapping to my dual variable supply and i can get the waveforms much better cleaner and a tiny ! tiny ! raster .
Its still far from the results of the other deflection circuit as you see below ,more work needed for sure on the klass circuits i want to see if i can match the results with he's circuit or at least know why either way .
Attachments
IMG_0174.JPG
IMG_0174.JPG (364.25 KiB) Viewed 5479 times
IMG_0168.JPG
Last edited by Harry Dalek on Sat Dec 02, 2017 5:17 pm, edited 3 times in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Klaas's magnetic deflection amplifier circuit

Postby Harry Dalek » Sat Dec 02, 2017 5:03 pm

Hi Klass

First up i have rewired the yoke to your instructions a few posts back results in pictures below and resistance a inductance readings now /.

Klaas Robers wrote:Harry, look on your +12 and -12 volt lines. I expect that they are not +12 and -12 all the scan time. Then you need a better power supply, one (two) that is better stabilized. At least for up to 1A. The current of the coil is not low. Under all circumstances they should keep their voltage. That may also clear up the cross talk of the two saw teeth and the messy pictures that you get.

good luck


The power supply i am using the transformer is 2 amp its pretty big ,i have a dual variable 35 volt supply and dual 12 volt ...did a test on a little 240 volt globe the dual variable supply and has enough amps to light this up a bit .

So i would say the power supply is ok as to up to the job its well rectified i have a few 5000 6000uf caps caps built into it as well .

Both deflection amplifiers are working testing now...but i have found reducing one of the supplies the amplifier sawtooth waveform becomes clearer ,it seems to like one or the other to be half its 12 volt supply around the 5 or 6 volts .

I also found it can be thrown into oscillation on voltage adjustments to , i can see all this on the scope .it will show a full scan line with no sawtooth input .

I had times where i could do this also with sawttooth as below but i don't think this looks correct more i tend to get a small line .

Last 2 picture is the raster i can get is pretty small swapping coil and amps and such not much difference but better than what i had yesterday ...
Attachments
IMG_0334.JPG
IMG_0336.JPG
IMG_0356.JPG
IMG_0353.JPG
IMG_0343.JPG
IMG_0338.JPG
IMG_0346.JPG
Screen 00002.jpg
Screen 00002.jpg (26.52 KiB) Viewed 5479 times
IMG_0361.JPG
IMG_0363.JPG
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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