The 3BP1 Anderson monitor

[Harry Dalek]

HI Steve Boy your Quick with your breadboarding !

I see all looks OK so far which is a dilemma ,i swapped all the CA3140s opamps back and its a touch worse as i was expecting but thinking about this , even so i don't think i tested the display result with that problem opamp in place as i have now..... because i was doing what you are now looking at the scope results ...this time its finished and i really just have to view and adjust best i can with that ca3140 ic603 in place .

Results were not as good as with the Ne5534 in place for ic603 but better than i was expecting all the problems are really still in the normal viewing i flipped to invert and it was spot on again viewing any thing ,normal as i mentioned is a touch worse and a bit tighter on the audio level.

I understand it the CA3140 should work ...something i noticed with this ic in place when i switched the monitor off the display looked good for that short time ..i am wondering if the opamp board is run on a lower voltage ,i see this ic works on 4 volts up, may be a slight lowering of its supply might fix our problem ?

The photos are of the reversing wav in normal viewing ......best i could adjust the monitor to display ,the last 2 are random video i had in invert worked great.

EDIT....some thing i forgot to mention is with no video the framing stops only works with detected video signal if i disconnect the monostable framing sync to the framing sawtooth board its back all the time ..not really a big problem or something i am worried about i just forgot to tell you before you left for that work trip a while back .

[Steve Anderson]

There is something fundamentally and major wrong here. This is not just a case of a slight delay in the clamp/sync pulse.

Supplies should all be +12V, none other. Chip types should be as designated. (Quad/dual/single versions OK when you can get them).

I'll do a few more tests in the morning, including making sure I've got the timebases right.

Forget using the reversing bars file for the moment, use the JLB1 file as it's recognisable. Make sure that the syncs are always negative as per my 'scope traces. Make sure you haven't got one or more of the 'scope inputs set to 'invert' or 'negative'.

The p-p video waveform at 6B should ideally be 1.5V, though 1-2V should be OK. If you're using a divide-by-ten 'scope probe (i.e. a 10M input impedance) then the scope should be set to 100mV/div and the video occupy 1.5 divisions. Once things are running sweetly, this isn't critical, but right now it is. My 'scope measures p-p voltages as you can see and it also detects if a 1:1, 10:1, 100:1 or a 1000:1 probe is being used and adjusts the display appropriately. For the older analogue scopes you have to do it in your head.

Read my previous posting and see if you can do the photography. I can't even make out what file you were using when you shot the previous photos.

Breadboarding is meant to be fast, I know there are those that loath it, but what takes a half day on any soldered method can be done in ten minutes. Changing a resistor value (as above) took maybe 20 seconds. If you breadboard in small chunks (as you would, or should, in a simulator) then all works well.

Steve A.

[Harry Dalek]

There is something fundamentally and major wrong here. This is not just a case of a slight delay in the clamp/sync pulse.

OH no a big problem Oh dear !~

Supplies should all be +12V, none other. Chip types should be as designated. (Quad/dual/single versions OK when you can get them).

OK i suppose you and or Klaas have worked out pulse video levels with it working on 12 volts .

I'll do a few more tests in the morning, including making sure I've got the timebases right.

Thanks Steve,i have to admit i am pretty perplexed at this problem

Forget using the reversing bars file for the moment, use the JLB1 file as it's recognisable.

OK sorry about that i was pretty rushed this afternoon so yes i will use that from now on.

Read my previous posting and see if you can do the photography. I can't even make out what file you were using when you shot the previous photos.

Steve A.

OH i didn't see that posting sorry , i think it is in that case best to go back to video gif files cameras a bit hit or miss on photos...the last 2 were just a testcard drawing i did a while back bit art deco i suppose no wonder you didn't work it out !

[Harry Dalek]

OMG it all works .
I think it has been for some time ,i had made a big mistake worrying about getting the reversing wav looking correct on the monitor this took me to swapping the ic603 for the Ne5534 work great for the reversing wav not for any thing else taking Steve's advice to swap back to the ca3140 opamp and checking with the JLB video wav which i tried tonight i was surprised it worked right away and every thing else as well i tried .
Results below ,pretty happy but upset i made Steve breadboard the circuit !

[Steve Anderson]

Well, that is good news! This was beginning to look like it was turning into a bad dream. But, well, it's done. Congrats!

As for the breadboarding what I have so far, it's not wasted effort, it's shown up one or two small matters that could be improved upon.

What I don't understand it why it dislikes the reversing bars waveform, I'll have a close look at that file and see if there's a reason for the the thing rejecting it.

Have you tried the monitor with real video? i.e. moving pictures, scene cuts etc..

Steve A.

[Harry Dalek]

Well, that is good news! This was beginning to look like it was turning into a bad dream. But, well, it's done. Congrats!

As for the breadboarding what I have so far, it's not wasted effort, it's shown up one or two small matters that could be improved upon.

What I don't understand it why it dislikes the reversing bars waveform, I'll have a close look at that file and see if there's a reason for the the thing rejecting it.

Have you tried the monitor with real video? i.e. moving pictures, scene cuts etc..

Steve A.

Yes i am very pleased it displays very nice !

OK hand in hands Steve held up high together done !

I don't understand the reversing wav visa versa problem either but it sure did make life interesting ,if i had checked the display with any thing else it might of showed up a lot earlier oh well never mind ,it works fine with every thing else i have tried now which is very good and what you would want Yes a very nice display and i didn't even adjust much apart from the brightness control so the camera could pick up the image better.

I was just thinking today at work i should try video i am Stuck in the SSTV mind set still images ,i will try that tonight for sure Steve..will post tonight.

[Harry Dalek]

Well took me a while to post this up trying videos tonight i ran into a problem none would play apart from this one all stills played fine , i think it is the video level the volume was pretty much tops by luck this one must of been just right but yes volume both on laptop and vlc player were pretty much up full.
I noticed on the pictures i do have to adjust the volume level on some .
I can play via the desktop to check this ...If needed Steve i can upload this video i played here and one that didn't work tonight to check the difference .
uploaded here the first video as a mp4 it plays better than a gif with frames missing

[Steve Anderson]

Yes, one of the problems with laptops is generally their low output signal level. You only need a few hundred milli-volts into 32 Ohm headphones for it to be plenty loud enough. Add to this the fact that most NBTV recordings are set at quite a low level whether on an audio CD or a wave file. If there were a standard set of input/output levels for domestic gear this might make sense, but there isn't. Even if there were, few seem to adhere to them.

Even amongst professional equipment where standards are defined there's quite a choice, from -24dbFS to -16dbFS in 2db increments, five in total. So even there it's a mess.

It may be worthwhile raising the gain of the input amplifier a bit. After I've run some errands I'll come back with a suggestion.

Steve A.

[Steve Anderson]

Harry, a quick check to see if low levels from the laptop are the problem, change R605 from 33k to 68k. This approximately doubles the gain but there is now a slight difference in gain between inverted and non-inverted inputs. If you also change R613 from 10k/11k to 12k the gains become x5.12 for non-inverted signals, and x5.67 for inverted inputs.

For now simply change R605, this should determine if low signal levels are the problem. But there's an increased risk of picking up noise and other crud so keep that in mind.

This may be the problem with the reversing bars signal, it's not recorded at the high-level of JLB1.

Steve A.

Later...Hans Summers noted that when his laptop was running on batteries there was no noise, but when plugged into the charger/PSU there was all sorts of crud everywhere. Disconnecting the mains also may break any noisy earth-loops. it depends on how your laptop is earthed, if at all, during charger/PSU use.

'Crud', word of the week!

[Harry Dalek]

Harry, a quick check to see if low levels from the laptop are the problem, change R605 from 33k to 68k. This approximately doubles the gain but there is now a slight difference in gain between inverted and non-inverted inputs. If you also change R613 from 10k/11k to 12k the gains become x5.12 for non-inverted signals, and x5.67 for inverted inputs.

For now simply change R605, this should determine if low signal levels are the problem. But there's an increased risk of picking up noise and other crud so keep that in mind.

This may be the problem with the reversing bars signal, it's not recorded at the high-level of JLB1.

Steve A.

HI Steve i followed your good advice on R605 and it sure worked every thing on on laptop nbtv wav video played fine even the old reversing wave showed up as it should of for the first time !

Now the volume control on the laptop works like another brightness control .

I am not to bothered about the invert it seems to work fine but if you want me to change it even things out no problems i am very happy the normal is spot on now !

Heres a few examples i tried this afternoon it was a bit light in my shed but still viewable.

[Steve Anderson]

OK, that's that sorted. There's a couple of things to remember here, first, the output from the laptop/CD player/whatever should be set such the video is about 1.5V p-p at 6B. Adjust the other controls to get a good picture, all being well the only control you should routinely adjust is the laptop volume control - but that's in an ideal world. You'll probably need to fiddle with others due to the care (or lack of it) in recording of the source material.

The 'invert' switch is for those using a device (often a portable audio CD player) that has inverted outputs. If you were only ever intending to use this one device as a source you could omit the 'polarity' switch...until someone gives you a recording that's also inverting. Two wrongs make a right. Undoubtedly it will happen and for the cost and effort of one switch and one resistor it's worth incorporating.

Now add a simple audio amplifier and you can watch NBTV content for as long as you have source material.

Harry, well done! Better than having that CRT kicking around in a drawer doing nothing! And you have a HV PSU you can use for other projects, it's plug-and-play!

Steve A.

Was the time and effort worth it? I hope Harry says yes.

[Harry Dalek]

OK, that's that sorted. There's a couple of things to remember here, first, the output from the laptop/CD player/whatever should be set such the video is about 1.5V p-p at 6B. Adjust the other controls to get a good picture, all being well the only control you should routinely adjust is the laptop volume control - but that's in an ideal world. You'll probably need to fiddle with others due to the care (or lack of it) in recording of the source material.

Now add a simple audio amplifier and you can watch NBTV content for as long as you have source material.

Steve A.

Thanks Steve ! Pretty much Done .
Funny enough most things i tried there was little i needed to do but will take your advice on .
Its doing very well with a wide range of video files made by different means ...I would be proud this came from my mind ...Well done Steve

[Steve Anderson]

Just one observation, there's a spurious white line often displayed at the top left of the screen where line 32 finishes. Not sure why. Harry, try fiddling with the 'course frame' and 'fine frame' controls first to get rid of this. You may have to adjust R623 as I did to 120k (or less) to eradicate this. It will also bring the first part of line 1 to where it should be.

Iterative tweaking, always part of an analogue design.

Steve A.

The first picture above is really nice, the display and the glow of the heater/cathode behind...

In time you could swap the deflection plates so the thing stands correctly instead of on its side, but that is being fussy! Or simply rotate the CRT.

[Harry Dalek]

Yes on that control Steve i can move it up or down adjusting that,i don't think it really bothered me that much so haven't bothered with it ,i know you want to know any quirks it might have .But its behaving ~!

[Steve Anderson]

Yea, kick back. You've done well. I hope an inspiration to others...

Steve A.