The Thylacine higher line rate monitor

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The Thylacine higher line rate monitor

Postby Harry Dalek » Thu Aug 03, 2017 7:25 pm

I have named this Monitor Build the Thylacine big brother to the Devil as the Tasmanian devil was to its bigger competitor the Tasmanian Tiger The Thylacine so in this case line rates touch under or over 100 lines .....well thats the plan ... :shock: any way i have the Devil working so just need a higher line rate monitor for the flying spot scanner camera build no use having it and no way to view it .
The problem with the Devil as Steve pointed out for any higher line rate is raster spot spot size and over lapping lines with the smaller electrostatic tube which i did notice on the 120 line tests .
So this is where i am at
I finished off the variable EHT and another inverter for the focus positive and working on the first sawtooth oscillator it will pretty much work off a dual 12 volt supply ,one circuit at a time and i know what works so using circuits i have used before here /
Everything working so far which is good ,i will fire it up again when i have at least a deflection amplifier working should be around the weekend if not both.
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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: The Thylacine higher line rate monitor

Postby Harry Dalek » Sun Aug 06, 2017 11:17 pm

I was ready to test the circuits for a raster today but it looks as if i stuffed up the positioning of the EHT module to close to its metal case and i didn't earth that ...not a good idea :roll:
least i took some photos of the saw tooth oscillator working before they got zapped i have got the framing one going again and just need to fix the line oscillator .
My plan today was to adjust the line frequency to 3khz and frame to 25 hz 120 line .
But back to fixing this first and giving it another go.
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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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Harry Dalek
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Re: The Thylacine higher line rate monitor

Postby Harry Dalek » Fri Aug 11, 2017 8:26 pm

Been working on the raster for this tube ... so far only getting part of the screen thats ok for now .

Mainly trying to work out the old problem of lines close to each other at the beginning of the scan and wider towards the end ,i have feed back and the frame deflection amplifier is not oscillating tried a low ohm resistors across the deflection coils that helped a little .

I am pretty much using the same circuit as i used for the Deep image Slow scan tv apart from a few changes to the circuit values around the line and frame sawtooth oscillators adjusted in this case 1.4khz and 25 hz or there abouts for now and the Tr19 20 base capacitor area on both deflection amplifiers to stop oscillation ...i found so far no need for one on the frame deflection amplifier no oscillation clean sawtooth ,i adjusted one for the best results on the line deflection amplifier .
Seems to make no difference to the frame deflection line closeness start or end of the frame till i get the the early uf capacitor valves then it drops the height to dramatically ....may be i have not found an in between valve yet .
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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: The Thylacine higher line rate monitor

Postby Steve Anderson » Sat Aug 12, 2017 2:43 am

Harry, how are you triggering the horizontal oscillator? Are you using the suggested BRY39? I assume you were not able to get the 1.3V VDR?

It looks like severe non-linearity in the horizontal oscillator and/or the output stage. The AD series of transistors were also germanium not silicon.

Steve A.
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Re: The Thylacine higher line rate monitor

Postby Klaas Robers » Sat Aug 12, 2017 6:19 am

And is the scanning not scanning up? From the bottom to the top? In most cases the lines are wide in the beginning of the scan and close at the end of the scan. This is then because the input saw tooth is not a linear sawtooth but a exponential saw tooth.

Look first at the wave form on the point where "1.7 volt" is indicated. The saw tooth there should be very linear. If not: as always, rubbish in - rubbish out.
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Re: The Thylacine higher line rate monitor

Postby Harry Dalek » Sat Aug 12, 2017 9:01 am

Steve Anderson wrote:Harry, how are you triggering the horizontal oscillator? Are you using the suggested BRY39? I assume you were not able to get the 1.3V VDR?

It looks like severe non-linearity in the horizontal oscillator and/or the output stage. The AD series of transistors were also germanium not silicon.

Steve A.


BTW the 74HC4040 ics turned up i just need the HC 4046 and i can test the flying spot sawtooth circuits.

I am using a replacement SCR C203B PRX same one i used in the Deep image SSTV heres the circuit i used with part changes for the SSTV vertical ...
viewtopic.php?f=19&t=2080&start=150
Part changes The VDR is replaced with 2 diodes ,the circuit change here on that was not my idea but some one who pasted on the changes 30 years ago to me ,the saw tooth oscillators seems to work .i will have another look how clean the sawtooth looks .
I will Draw up changes i have made to this one as these circuits posted up here are adjusted to SSTV.
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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: The Thylacine higher line rate monitor

Postby Harry Dalek » Sat Aug 12, 2017 9:07 am

Klaas Robers wrote:And is the scanning not scanning up? From the bottom to the top? In most cases the lines are wide in the beginning of the scan and close at the end of the scan. This is then because the input saw tooth is not a linear sawtooth but a exponential saw tooth.

Look first at the wave form on the point where "1.7 volt" is indicated. The saw tooth there should be very linear. If not: as always, rubbish in - rubbish out.


ITs might be how i have connected the deflection yoke or positioned upside down i have not really looked into which way i have connected it all here apart from horizonal deflection to its yoke coil vertical to its .

OK Klass i will have another look at the sawtooth here ..i was mainly looking at the deflection circuits but i see your point ...
'i will post up results
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: The Thylacine higher line rate monitor

Postby Harry Dalek » Sat Aug 12, 2017 8:33 pm

I drew up the circuit changes with my part substitutions, the horizontal and vertical are near one the same apart from the deflection yoke values .\
Changed today whats in the schematic... adjusted the voltage to the sawtooth circuit via lm317 seems to give best results at 10 volts
I found its a touch better now and at higher line rates the line spacing is much better not as noticeable lower you go it does show up .
Not overly high line numbers with a 30hz vertical i was testing ..with the new voltage control its changed the sawtooth oscillators range a touch.
I can hard wire the flying spot scanner sawtooth to the deflection amps and by pass these no need to sync then but these come in handy for testing the thing ..i know theres more work to do here but getting there .
The sawtooth readings are from the testpoint base 2n3904...
Below the adjustment tests i have better position control with the vertical ,horizontal has a little movement not overly great here .

youtu.be/TlFlgHxhfjg
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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: The Thylacine higher line rate monitor

Postby Klaas Robers » Sat Aug 12, 2017 8:50 pm

Very good! But at the base of the 2N3904 I see that the frame sawtooth is still not ramping straight. This might be because of the type electrolytic capacitor of 200 uF. This should be a tantalium capacitor. The aluminium capacitors when discharged, they still keep some of their charge, which returns just after the discharge. That gives a bended sawtooth.
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Re: The Thylacine higher line rate monitor

Postby Harry Dalek » Sat Aug 12, 2017 9:14 pm

Klaas Robers wrote:Very good! But at the base of the 2N3904 I see that the frame sawtooth is still not ramping straight. This might be because of the type electrolytic capacitor of 200 uF. This should be a tantalium capacitor. The aluminium capacitors when discharged, they still keep some of their charge, which returns just after the discharge. That gives a bended sawtooth.


Yes at that test point is where that scope reading was taken ...i was using titanium capacitor Klass ,i had a standard one when i first tested still soldered in there on the multi position switch 1 of 4 on the vertical sawtooth oscillator not used at the moment the titanium is.... i was hoping i had used a standard type but no it is the better type ...now this is harder more head scratching !
I will look into this see if i can work it out ...you have good eyes on this !
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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Harry Dalek
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Re: The Thylacine higher line rate monitor

Postby Klaas Robers » Sat Aug 12, 2017 11:51 pm

In any way, see first that the sawtooth at the base of the 2N3904 is linear, not bended. Also look at the sawtooth form at the emitter of this transistor. This should have the SAME FORM. If that is correct, don't suspect the amplifier right of the 2N3904.
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Re: The Thylacine higher line rate monitor

Postby Harry Dalek » Sun Aug 13, 2017 10:58 pm

Klaas Robers wrote:In any way, see first that the sawtooth at the base of the 2N3904 is linear, not bended. Also look at the sawtooth form at the emitter of this transistor. This should have the SAME FORM. If that is correct, don't suspect the amplifier right of the 2N3904.


I had a good look around the area today all looks about the same at the emitter... looking at the sawtooth oscillator it seems to be where its caused i tried a few things to correct it best results were a diode across the BC547 and 549 emitters the old SSTV version has a resistor and capacitor here .
Its a slight improvement and seems to work as well much better than without it.
I also looked into the position and size problems size wise the vertical pretty much can fill the screen top to bottom but horizontal half to a touch less /
Position... verticals position controls pretty good horizontal only middle to the side.
I tried every thing i could think of increasing the horizontal line apart from increasing voltage to its deflection amplifier its understandable the problem its deflection coil is only 1.5 ohm .
So to get a better aspect ratio i stuck a low ohm resistor on the vertical deflection coil and dropped its scan back so at least that works with the horizontal for now .
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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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Harry Dalek
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