Hilger & Watts Autocollimator and Clinometer

[DDijkman]

Hello,

Some weeks ago I managed to acquire a very nice Hilger & Watts TA53 Autocollimator and a Hilger & Watts "Large precision clinometer TB80".
The autocollimator is of the Photo-Electric type, this means that there is a LDR (Light-dependent resistor) built in the autocollimator that can take the readings for you. It does however need a display unit which I am missing, and of course these things are as rare as unobtainium hens teeth.
So my plan is to build one, perhaps a more modern and sophisticated one with more features.
My plan is to somehow digitize the analogue signal and send it to an arduino and perhaps a computer.
My electronics knowledge is somewhat limited so i'm going to need some help, ive already been talking to Peter Lambrecht who made the electrical schematic for the original display unit and got a ton of other information. Thanks Peter, and by extension Daryl Bane!!

What i'm currently trying to figure out is what voltages go to the vibrator sled and photo conductive cell.
There seems to be a difference in voltage output to the autocollimator from different types of display units, there is also a difference in resistance in the vibrator sled and photo conductive cell depending on what type H&W autocollimator you have?
The resistance of the vibrator sled and photo conductive cell on my AC happens to be 44.5ohm and more than 40Mohm (could mearuse properly because my multimeter peaks at 40Mohm)
In the next post i've uploaded the schematic and a list op component values in the hopes that some of you could help me.

With my H&W set also came a transformer for the light source but it is very heavy and bulky so i decided to design and 3D print a light fixture that houses 2 AA bateries a switch and and an On/off indicator light. It screws on the back of the original light bulb housing and should work for 5,5 hours with the original buls depending on what type AA batteries you use. Ive included some pictures of the thing.
If any of you are interested I will gladly share the designes, just send me a message!


The H&W "Large Precision clinometer TB80" remains a bit of a mystery to me because i cant find anything online, no manual no other pictures of this particular unit. I think i know how it functions but would very much like a manual, so if you know where to find one please let me know!

Thanks,
Dennis

 

[DDijkman]

Here you can find the electronic schematic of the display unit (FA 70-3) with a list of component values.

FA 70-3 circuit diagram 2.jpg - Google Drive

FA 70-3 circuit diagram components.jpg - Google Drive

 

[Mr_CNC_guy]

You said that the vibrator sled resistance is over 40M Ohms?
The parts list says that it should be 60 Ohms. You must have a
burned out coil or broken wire. What does the vibrator sled do anyway?

If the photo sensor is just an light sensitive resistor which would be
reasonable given it's age then you should be able to use an ohm meter
to take your readings. No need for a fancy tube (valve) circuit.

What does the photo sensor look like? A picture would help.

 

[DDijkman]

No, the vibrator sled measured 44.5Ohms and the photo conductive cell measured over 40Mohms. There seems to be some differance in values depending on what autocollimator you have.
I will include a picture of the photo sensor, but its not really helpfull because its build in the autocollimator and not really visable. Also not easely removable without messing up the allignment.


the photo sensor is on the bottom where the 2 big wires go to.

 

[Mr_CNC_guy]

My back of the envelope calculations says that 33 volt DC is applied
to the sensor through a 470K Ohm resistor. The signal from the sensor
must have an AC result that is fed to a balanced amplifier tube V101.
If you put 33 volts DC fed through a 470K Ohm resistor you will
replicate the power from the circuit.

The AC is likely to be the result originating from the vibrator mechanism.
To read the result use some capacitor larger then .02 uF with a voltage
rating over 50 volts. Connect that to your digital voltmeter and
set it to read AC. The signal is likely to quite small but the tube
circuit is nothing magic. It is only a single tube balanced amplifier,
quite standard for the day.

You should see the AC voltage go up and down as you adjust the autocollimator.
What the reading means is dependent on the optical design of the device.
I would expect a peak or a null when the alignment is correct, but
I am just guessing here.

 

[DDijkman]

Thanks for the input! And you are correct. And with the help of some people from another forum i was able to get it to work and actually measure it with my oscilloscope. Ive attached some pictures that show the 50Hz input sine wave to the vibrator sled (yellow line) and the output of the LDR (blue line) changing with the change in reading on the autocollimator.

I will work on this some more and keep you posted.

 

[fobyellow]

Thanks for the input! And you are correct. And with the help of some people from another forum i was able to get it to work and actually measure it with my oscilloscope. Ive attached some pictures that show the 50Hz input sine wave to the vibrator sled (yellow line) and the output of the LDR (blue line) changing with the change in reading on the autocollimator.

I will work on this some more and keep you posted.

View attachment 320908View attachment 320909View attachment 320910View attachment 320911

Hello DD:
I have a similar HilgerWatts autocollimator TA58, but the meter part is missing, could you please tell me the another forum you reffered, i want to restore it,thanks
this is a servo-controlled autocollimator, i think the vibrating slit and photocell may be the same. the final reading is though a potentiometer also driven by motor.

 

[ballen]

Here you can find the electronic schematic of the display unit (FA 70-3) with a list of component values.

FA 70-3 circuit diagram 2.jpg - Google Drive

FA 70-3 circuit diagram components.jpg - Google Drive

This is very valuable information for anyone who wants to maintain these devices!

Unfortunately these links don't work for me. If something is wrong with them, could you please edit your post to fix them? The uploaded versions are not high enough resolution to read.

 

[fobyellow]

I think i just found the topic, https://www.circuitsonline.net/forum/view/154259/1

finally i understand the principle of vibrating slit, it could produce sinewave use only one undirectional photocell (which indicates the displacement of image and photocell ), then use a phase-detector to rectify the amplfied voltage signal, tune the drum, when the rectified voltage goto zero, means the slit is sitted in "middle".

the google drive link is bad. i have 2 schematics, its too too old, the vibrator is driven directly from buck transformer, so the voltage and harmonic noise may cause uncertainty

 

[DDijkman]

This is very valuable information for anyone who wants to maintain these devices!

Unfortunately these links don't work for me. If something is wrong with them, could you please edit your post to fix them? The uploaded versions are not high enough resolution to read.

Hello, did you get the information you where looking for?
If not, please send me a private message, i might have some more information about autocolimators you would like.

All the best, Dennis.

 

[DDijkman]

I think i just found the topic, https://www.circuitsonline.net/forum/view/154259/1

finally i understand the principle of vibrating slit, it could produce sinewave use only one undirectional photocell (which indicates the displacement of image and photocell ), then use a phase-detector to rectify the amplfied voltage signal, tune the drum, when the rectified voltage goto zero, means the slit is sitted in "middle".

the google drive link is bad. i have 2 schematics, its too too old, the vibrator is driven directly from buck transformer, so the voltage and harmonic noise may cause uncertainty
View attachment 372052

View attachment 372053


View attachment 372054

Hello, did you get the information you where looking for?
If not, please send me a private message, i might have some more information about autocolimators you would like.
I also managed to plug the autocollimator into an Arduino.

All the best, Dennis.

 

[ballen]

Private message sent...

 

[fobyellow]

Hello, did you get the information you where looking for?
If not, please send me a private message, i might have some more information about autocolimators you would like.
I also managed to plug the autocollimator into an Arduino.

All the best, Dennis.

thankyou for your reply, i read the whole topic, i think you are trying to use LED to get the sync signal, calculate the positive and negative RMS voltage. how does it work? i'm worring about the pahse signal that you retrieve from the vibrator excitation, the led wont open before 1.9V(or some other voltage), so the signal would be delayed, will it matter??

i intend to modify it to battery power, so the following schme is what i am trying, there are still some problems to work:

the vibrator is electro-magnitic , it has a movable mass mayle pendulum, so it is a forced pendulum oscillation, the actual move of the "slit" is behind the sin signal, so the comparator output is only sync to excitation, but not to the movment. should there be some phase-shift circuits??

 

[DDijkman]

thankyou for your reply, i read the whole topic, i think you are trying to use LED to get the sync signal, calculate the positive and negative RMS voltage. how does it work? i'm worring about the pahse signal that you retrieve from the vibrator excitation, the led wont open before 1.9V(or some other voltage), so the signal would be delayed, will it matter??

i intend to modify it to battery power, so the following schme is what i am trying, there are still some problems to work:

the vibrator is electro-magnitic , it has a movable mass mayle pendulum, so it is a forced pendulum oscillation, the actual move of the "slit" is behind the sin signal, so the comparator output is only sync to excitation, but not to the movment. should there be some phase-shift circuits??


View attachment 372342

Hi,
Sorry for the late reply but I'll try to explain some of the questions I think you're asking.
First of, I didn't use any Leds in my attemps to read the output signal. This was done by one of the guys on the forum to simulate the vibrating slit and do some testing.
As far as i understand it the vibrating slit needs AC power (it needs positive and negative voltage at 50Hz) to function, maybe you could simulate this with DC power but i'm not sure.
As for the fase shifting circuit, I really dont know. Sorry but I'm not that good at electronics. I dont believe the orignal circuit has one?

I'll ad a picture of the circuit I use to be able to read the outgoing circuit with an oscilloscope.
I hope this will help you some, sorry i couldnt be of more help.

All the Best,

Dennis

 

[ballen]

Dennis, what is the purpose of the vibrating slit? How does it work? Is the idea that at some point during the motion, that slit crosses the line generated by the autocollimator reflected image? So that at some point during the motion, the intensity drops (because the line is black, so there is less light and less photocurrent)? Does this drop in photocurrent occur twice during a single 50 Hz cycle? And if the reflected image of the line is in the middle, then these two drops are equally-spaced (10 ms apart) whereas if the reflected image of the line is off-center then these two dips are not equally-spaced (say 8ms then 12ms apart)? Cheers, Bruce

 

[fobyellow]

Hi,
Sorry for the late reply but I'll try to explain some of the questions I think you're asking.
First of, I didn't use any Leds in my attemps to read the output signal. This was done by one of the guys on the forum to simulate the vibrating slit and do some testing.
As far as i understand it the vibrating slit needs AC power (it needs positive and negative voltage at 50Hz) to function, maybe you could simulate this with DC power but i'm not sure.
As for the fase shifting circuit, I really dont know. Sorry but I'm not that good at electronics. I dont believe the orignal circuit has one?

I'll ad a picture of the circuit I use to be able to read the outgoing circuit with an oscilloscope.
I hope this will help you some, sorry i couldnt be of more help.

All the Best,

Dennis

the photocell is used to aim the target, so you need to get the sync signal before you to integration.

the photocell is a photo-resistor, so the signal may be DC+AC, but the interesting part is the time that the "slit" passby and return, you can always have a SIN+DC signal from your ADC, but you dont know the time that the movment direction changes. The meter part of this collimator is not used to directly read the result of angle, but only to tell you if the collimator is perfectly aimed at the same position (by adjusting the drum wheel). so we are not measuring the voltage of photocell, but trying to measure the time of the vibrating slit whenever change direction. the sync signal is necessary and vital.

the original circuit does have a phase sensitive rectifier, the reference phase signal is supplied by the 3-15V winding from the mains transformer while the vibrating slit is also powered my the same transformer, so the reference phase from the mains transformer is synchronized with the amplified photocell signal

i'll post the test result later

 

[fobyellow]

i made a test circuit, the OP-driver is not strong enough to drive the coil, so the amplitude of vibration is not enough, but you can already see the difference between aiming targets.the excitation signal is 75Hz

the photocell circuit is not amplfied, just Gain=1 buffer


the blue channel is the sync-signal of excitation signal, the yellow channel is the buffered photocell signal, the following graph is taken when the slit is on up side of the center point, you can see the rising edge correspond the 90 degree of a sin signal


then i turn the drum wheel a little bit, the slit is on bottom side of the center point, the photocell signal shifts 180 degree as follows


the third graph, the slit is "almost" at the center point, so the signal appears like 150Hz,


if using psd circuit, you can filter the noise, and get the perfect center point because each side around the center point contribute the same half signal, they are 180 degree phase shifted by SYNC, so the rectified DC signal equals to 0. thats why the meterbox doesnot have a scale unit, they are only used to point zero

 

[LayoutInspector]

Hi, I just found this thread while doing some research and thought I’d add to it since it’s current. I don’t know much about this device yet but I just ended up with one that is similar enough to the discussion. It doesn’t power up. The autocollimator is TA 3-2 on the base. The electronic display is FA70.4

I’m guessing that the electrolytic capacitors are dry in the electronic display. One actually looks a little leaky. The rubber stoppers on both ends of the electrolytic capacitors seem dry.

Calibration sticker on the optics is from 45’ if that date seems correct. It’s kind of weird that I’m at an age where this thing wouldn’t have seemed that old when I was a child but it’s also old enough that I could see it turn 100 in my lifetime lol.

I haven’t posted pictures on this site, so I have a little reading to do. File size too large error on my first couple attempts. In any event, I make myself available for questions about this equipment. I don’t know a whole lot about it but maybe I can still help in some way.

Thanks

 

[DDijkman]

Hi, I just found this thread while doing some research and thought I’d add to it since it’s current. I don’t know much about this device yet but I just ended up with one that is similar enough to the discussion. It doesn’t power up. The autocollimator is TA 3-2 on the base. The electronic display is FA70.4

I’m guessing that the electrolytic capacitors are dry in the electronic display. One actually looks a little leaky. The rubber stoppers on both ends of the electrolytic capacitors seem dry.

Calibration sticker on the optics is from 45’ if that date seems correct. It’s kind of weird that I’m at an age where this thing wouldn’t have seemed that old when I was a child but it’s also old enough that I could see it turn 100 in my lifetime lol.

I haven’t posted pictures on this site, so I have a little reading to do. File size too large error on my first couple attempts. In any event, I make myself available for questions about this equipment. I don’t know a whole lot about it but maybe I can still help in some way.

Thanks

Hello,

Nice find! Would love to see some pictures! I hope you'll get it working agian. If you do, I'll have some questions about the signal coming from the autocollimator going to the electronic display. And probably some other questions.

All the best,
Dennis

 

[daryl bane]

I picked this up many years ago on Ebay, during the Great Shop cleanout era. All works just fine. the Lewis pads were a bonus. Unfortunately I am a electronic idiot and really can't give any educated values.