Photomultiplier Tubes camera build

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Re: Photomultiplier Tubes camera build

Postby gary » Tue Dec 27, 2016 8:10 pm

Harry I haven't the foggiest clue - it's interesting though. if you played music through it you would get a nice echo effect ;-) Maybe it's the ghost of Elvis?

All I can say is I hate laptops.
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Re: Photomultiplier Tubes camera build

Postby Harry Dalek » Tue Dec 27, 2016 8:43 pm

gary wrote:Harry I haven't the foggiest clue - it's interesting though. if you played music through it you would get a nice echo effect ;-) Maybe it's the ghost of Elvis?

All I can say is I hate laptops.


Both play back record are set at 48khz ..i don't have special effects for the sound like you can change on some computers volume only so thats not it.

I should make a NBTV Elvis file then there will be a Ghost :idea:

i am still thinking its the cable stereo sound going to a mono jack there could be some thing to do with it ...i will play around some more just another little problem :roll:
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Re: Photomultiplier Tubes camera build

Postby Harry Dalek » Tue Dec 27, 2016 11:10 pm

OK Gary i think i have got it .
i swapped over to my other lap top with a line input jack and funny enough its got controls to adjust a range of settings on audio and it was set on generic and i got that ghosting as before on my other computer ..once i set it to none all was fine so was not the cable i was thinking ...

BTW whats the prometheus line rate setting been having a look at the controls you have put in ?
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Re: Photomultiplier Tubes camera build

Postby gary » Wed Dec 28, 2016 10:19 am

Harry Dalek wrote:OK Gary i think i have got it .
i swapped over to my other lap top with a line input jack and funny enough its got controls to adjust a range of settings on audio and it was set on generic and i got that ghosting as before on my other computer ..once i set it to none all was fine so was not the cable i was thinking ...

BTW whats the prometheus line rate setting been having a look at the controls you have put in ?


Aha that's better.

You can see the spec for Prometheous in the Video2NBTV format window - it it isn't there move this file (after unzipping) into the vide2nbtv program folder:

PrometheusRenderer.zip
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The format is actually generated on a raspberry pi.

More info here: viewtopic.php?f=10&t=1760&p=15895&hilit=prometheus#p15895

and here:
https://www.youtube.com/user/monroelkjr/videos
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Re: Photomultiplier Tubes camera build

Postby Harry Dalek » Wed Dec 28, 2016 6:38 pm

gary wrote:]

Aha that's better.

You can see the spec for Prometheous in the Video2NBTV format window - it it isn't there move this file (after unzipping) into the vide2nbtv program folder:

PrometheusRenderer.zip


The format is actually generated on a raspberry pi.

More info here: viewtopic.php?f=10&t=1760&p=15895&hilit=prometheus#p15895

and here:
https://www.youtube.com/user/monroelkjr/videos


OH yes thats jogged my memory ,yes the 48 line information window worked copying that file over to video2NBTV...

I tried it out in video2nbtv with the web cam worked well .

Now i have worked out your NBTV player recorder it will be used i will try it on the camera soon its a lot easier than the audio recording software .
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Re: Photomultiplier Tubes camera build

Postby gary » Wed Dec 28, 2016 6:46 pm

Harry Dalek wrote:
Now i have worked out your NBTV player recorder it will be used i will try it on the camera soon its a lot easier than the audio recording software .


Well if it proves to be useful I am pleased.
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Re: Photomultiplier Tubes camera build

Postby Harry Dalek » Wed Dec 28, 2016 9:37 pm

gary wrote:
Well if it proves to be useful I am pleased.


I think a few other nbtvers will as well if they stumble across it here ...its now my my Gary folder !

Got once again side tracked here but for the same goal improving ...tomorrow i will get back at it .
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Re: Photomultiplier Tubes camera build

Postby Klaas Robers » Thu Dec 29, 2016 5:56 am

Today I received the new Newsletter and in it Karen Orton writes that her optical proximity detector gives a sine wawe rather than a square wave. So this looks to be normal. Then it is useless to extract a sync pulse from, too uncertain. However to use it for speed control might use as the mechanical system is too slow to follow the jitter in the optical output pulses.

So Harry, nothing unusual with the optical read out. If you want to know more, ask Karen. The MUTR NBTV monitor also uses this optical sensor and PLL servo for speed control and it works.
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Re: Photomultiplier Tubes camera build

Postby Harry Dalek » Thu Dec 29, 2016 7:58 pm

Klaas Robers wrote:Today I received the new Newsletter and in it Karen Orton writes that her optical proximity detector gives a sine wawe rather than a square wave. So this looks to be normal. Then it is useless to extract a sync pulse from, too uncertain. However to use it for speed control might use as the mechanical system is too slow to follow the jitter in the optical output pulses.

So Harry, nothing unusual with the optical read out. If you want to know more, ask Karen. The MUTR NBTV monitor also uses this optical sensor and PLL servo for speed control and it works.


Hi Klass

I am a bit on and off with the member ship so i have not seen Karens work on the proximity detector unfortunately ,this is the first i have heard of it but i gather she is using it as a replacement for the current methods for producing mechanical sync perhaps ? any case interesting .

Funny enough i have been looking into all of the motor control today ..

A while ago i mentioned to Gary the problem seems to be around the PLL and pretty much nothing out of pin 13 ,running the PLL on 5 volts nothing ...i swapped over to the 12 volt supply and i get a quick sign of a pulse and it disappears ..
So adjusting the voltage to 11.55 volts it appears fine now what i don't understand is why this CD4046BE Pll is so voltage sensitive ...i swapped over the ic but same result i want to track down another version as it could be just this version of the ic playing up .
Took me most of the day looking into seeing if i could improve the sync pulse trying to straighten it up its a bit better it does seem to be the position angle and such from the encoder ......other factors like at the moment out of range repositioning i will have to look again when i have time to see it that helps more .
I really need to get the motor control working again and as you say Klaas it should work ,i will just need to stick with it ...having a pulse out of the 4046 now should help ! :roll:
BTW pin 9 at times is shown to be grounded other schematics of this motor control its just pins 5 and 8 ...why is this so....?
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Re: Photomultiplier Tubes camera build

Postby gary » Fri Dec 30, 2016 6:14 pm

Klaas Robers wrote:Today I received the new Newsletter and in it Karen Orton writes that her optical proximity detector gives a sine wawe rather than a square wave. So this looks to be normal. Then it is useless to extract a sync pulse from, too uncertain. However to use it for speed control might use as the mechanical system is too slow to follow the jitter in the optical output pulses.

So Harry, nothing unusual with the optical read out. If you want to know more, ask Karen. The MUTR NBTV monitor also uses this optical sensor and PLL servo for speed control and it works.


Yes, Klaas but all optical sensors exhibit that to some degree (aperture distortion), there is usually only a problem if there is no pulse shaping performed prior to feeding it into the PLL (in my case I use 555s, In Harry's case he uses a comparator) - as Karen says, the problem only exists "without additional active components". As long as the frequency and phase of the "sinusoidal" pulses is correct, the pulses AFTER pulse shaping *should* be correct.
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Re: Photomultiplier Tubes camera build

Postby Klaas Robers » Fri Dec 30, 2016 7:17 pm

You are right Gary, but what if the comparator shows some form of oscillation on the moments that it should switch from low to high, or reverse? What if some intereference is on the slow sinewave input signal, or some other noise? Then the comparator might give not just one transient at the time, but one (or more) pulses at the transient time. These are very difficult to capture, but the 4046 might react on it. The phase comparator is a strange counting circuit, I don't know what it does under these circumstances. See a double pulse?

I see in the circuit diagram of the MUTR-kit that they use a Schmidt trigger in stead of a comparator, a high ohmic resistor from the output to the + input. I cannot find the isolated circuit diagram back in my computer, but I still have the chapter 11 in the NBTV Handbook, where it is published.
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Re: Photomultiplier Tubes camera build

Postby gary » Fri Dec 30, 2016 10:52 pm

Klaas Robers wrote:You are right Gary, but what if the comparator shows some form of oscillation on the moments that it should switch from low to high, or reverse? What if some intereference is on the slow sinewave input signal, or some other noise? Then the comparator might give not just one transient at the time, but one (or more) pulses at the transient time. These are very difficult to capture, but the 4046 might react on it. The phase comparator is a strange counting circuit, I don't know what it does under these circumstances. See a double pulse?

I see in the circuit diagram of the MUTR-kit that they use a Schmidt trigger in stead of a comparator, a high ohmic resistor from the output to the + input. I cannot find the isolated circuit diagram back in my computer, but I still have the chapter 11 in the NBTV Handbook, where it is published.


Indeed, a comparator can chatter when the inputs are nearly level but I thought this was only a problem for (really) slow moving input and is solved by adding a little positive feedback (effectively making it a Schmitt Trigger). I haven't used an LM311 in this application but it seems to be reasonably popular.

Indeed my 555 was also configured as a Schmitt trigger - I always seem to have 555s lying around and NOT the preferred chip, so it's pressed into service. I seem to remember I needed 2 555s to do the job - alas I never seem to document these things.

In any case, I agree, if there is chatter I would bet that it wouldn't do the PLL any good (and therefore motor speed control) that's for sure.

Harry you might want to try a 100k resistor between pin 7 and pin 2. That should give it enough hysteresis to prevent chatter. I am not sure if this will slow it down too much however, someone with more experience may wish to comment.

Here is the MUTR circuit: viewtopic.php?f=1&t=736&p=5915&hilit=MUTR+kit+circuit+diagram#p5915
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Re: Photomultiplier Tubes camera build

Postby Steve Anderson » Sat Dec 31, 2016 9:16 pm

Chasps, It's often preferable to have some form of positive feedback around a comparator to stop this errant behavior. As Gary says this turns it into a Schmitt-trigger. The advantage with something like an LM311 is that you have complete control over what levels you wish the output to change state, from hi-to-lo or the reverse.

I can certainly make a suggestion, but I will need a circuit of how it is currently configured showing the input source(s) and load, as well as the signal level(s) being fed into this stage. Max pos, Min neg.

Often you don't need to use a 'proper' comparator, depending on what it's feeding and the speed required, even a 741 can be used. There's not a great deal of difference between them, except that a comparator usually has a logic-compatible output (311) and is never used with negative feedback like an op-amp as it's unlikely to be stable. (There are always exceptions though).

Indeed, Gary's link to the MURT device shows a LM324(d) used as a comparator, note the resistor from the output to the non-inverting input (+). This is positive feedback which is required to get the fastest and cleanest switching required.

Harry, post the circuit and I'll have a look.

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Re: Photomultiplier Tubes camera build

Postby gary » Sat Dec 31, 2016 10:04 pm

Steve Anderson wrote:Chasps, It's often preferable to have some form of positive feedback around a comparator to stop this errant behavior. As Gary says this turns it into a Schmitt-trigger. The advantage with something like an LM311 is that you have complete control over what levels you wish the output to change state, from hi-to-lo or the reverse.

I can certainly make a suggestion, but I will need a circuit of how it is currently configured showing the input source(s) and load, as well as the signal level(s) being fed into this stage. Max pos, Min neg.

Often you don't need to use a 'proper' comparator, depending on what it's feeding and the speed required, even a 741 can be used. There's not a great deal of difference between them, except that a comparator usually has a logic-compatible output (311) and is never used with negative feedback like an op-amp as it's unlikely to be stable. (There are always exceptions though).

Indeed, Gary's link to the MURT device shows a LM324(d) used as a comparator, note the resistor from the output to the non-inverting input (+). This is positive feedback which is required to get the fastest and cleanest switching required.

Harry, post the circuit and I'll have a look.

Steve A.


Hi Steve, cheers, although I am familiar with the principles it has been some time since I have physically played around with comparators, it's useful to have the opinion of someone with more up to date practical experience.

Here is the cct that Harry has posted and is using AFAIK - I think it is safe to work on that, I am sure Harry will correct me if I am wrong.

download/file.php?id=9589
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Re: Photomultiplier Tubes camera build

Postby Harry Dalek » Sun Jan 01, 2017 1:10 am

Sorry for a late reply Steve Garry been very busy with work .
Yes Gary I will give the 100k resistor a go ..bit of feed back..
Version 3 schematic viewtopic.php?f=8&t=2139&start=210
i think that was the first one i posted up gary on your post
The mistake i have found trying to get a signal out of pin 13 was i can't connected it as is right the gate of the mosfet it stops the pulse ..as mentioned before i can only get the pll working at a narrow range of voltage below 12 volts 11,55 volts seems good .
i more than likely need the 100k resistors before the mosfet as in the club circuit for the motor control ...which i would rather anyway knowing thats how it should work .
Hope to work more onit tomorrow or today really ..and happy new year !
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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