Ok thanks. I really don't need another shutter tester, but I have been wanting to get into Arduino since I first saw it, so this will be my first project.
Hi,
looks like that board, you can plug in a 9V or maybe 12V power supply & the board has a voltage regulator.
I just connect mine up to the computer via the USB socket.
For stand alone, just use a phone charger with the right lead to plug into the USB socket.
What do you use to check the calibration? Think you maybe chasing your tail with this one.
I was thinking of this board
The issue (with my present shutter tester) is the photodiode turns ON too soon and turns OFF too late as the shutter slit passes.
That board doesn't add much or anything that a Nano doesn't have, except pins. It uses the same kind of voltage regulator (typically a LT1117 clone) that the Nano's (and its clones) also use - with the same limitations. These don't matter in this project since power consumption is very low, and as such, the onboard regulator of the Nano will do just fine. Just hook up/daisy-chain everything to the 5V pins of the Nano.
I doubt the kind of laser gates used here have any problematic delay. It will likely be in the 1us-10us range and that's being pessimistic. This would be a 2% error at most at a 1/1000 shutter speed.
Sorry, I see what you mean now. You're right; you'd have to either determine the width of the beam at the sensor site or calibrate the way you proposed.
I just had some time to go over the code and wonder if one can use this tester to set the closing curtain brake.
For example on the Calumet tester, it resets on the closing side if the shutter bounces open and will display a very short time; just the time of the bounce. You can keep tightening the brake until this second small time goes away.
I'm not sure on this tester how quickly it resets when there are two open-close sequences close together.
Here's a pic of my tester. Code based on the Cameradactic design, I added the LCD screen. Single sensor for now. Most of my camera have leaf shutters, and half my focal-plane cameras are medium format so the spacing would have to be adjustable.
Shutter speed tester by Olivier, on Flickr
If this model will work with the attachInterrupt() call
A photoresistor doesn't sound very appropriate in a shutter tester circuit. LDR's have response times of several (up to dozens) milliseconds.
Yeah, it will. If it's a sensible approach, and how to make it fail-safe, is another matter. See my earlier comments in the thread on debouncing. How often will that pin change interrupt fire as the light level changes? Be sure to handle the possibility that it bounces a couple of times in the process.
I found a basic circuit on Wokwi. Moving the slider changes the reading on the sensor from binary high to low.
If this model will work with the attachInterrupt() call, I can simulate shutter opening and closing by moving the slider and play with the code.
The model as it is uses "digitalread()" so I need to see if it works with attachinterrupt().
View attachment 332884
I really think, trying to make a 'simple shutter tester that works' to the same specification of a commercial test unit costing £££k is a non-starter.
Huh? I suggested no such thing. I just pointed out that a $0.10 LDR is less suitable than a $0.10 phototransistor.
As to debounce: opinions and preferences vary. Note that 16MHz (typical Arduino Nano clockspeed) on an Atmega is really oodles of computing power for the simple task presented here - including debouncing.
Of course, with inefficient programming, even a 240MHz ESP32 will be borderline sufficient. As they say: it's not so much what you've got, but how you use it...Also, smart code adds nothing to the BOM or project cost.
Please also note my comment w.r.t. debounce was directed at the thing ic-racer found that most certainly doesn't show anything that has hardware debounce; refer to the "schematic".
Finally, please also note that a Schmitt trigger in itself is not a debounce circuit, but can be a (very useful) part of it.
This is the simulation I came up with. On Wokwi, it only allows simulation of a single attachinterrupt( ) at input #2; input #3 does not work.
So it is only able to simulate the single sensor component, though the entire code for both sensors is in the model.
Nothing really to change with the core code for focal plane shutters but I made the simulation so I could try adding some extra features specific to the cameras I repair. For example closing curtain bounce detection, calibration, leaf shutter mode, external controls, etc.
For leaf shutters I will use a diffuse light source and I'll track the analog output of the sensor and define the size of the intensity parallelogram to calculate the speed, etc.
Hi, it was a follow on from IC, not sure what he was trying to achieve with a light sensor circuit to simulate a shutter?
Woki is really great for trying certain things, but in this case, I'd really just test using the real stuff. Makes so much more sense, and it doesn't cost that much more time or money than a simulation.On Wokwi [...]
For leaf shutters I will use a diffuse light source and I'll track the analog output of the sensor
I'm guessing the slider controls some light dimmer app & the arduinio is measuring light intensity?
It is running your program.Really not sure what this is trying to do?
Yes. A simulated light shining on the sensor.There is no slider input to the Arduino, so I'm guessing the slider controls some light dimmer app & the arduinio is measuring light intensity?
It would be better to use the dedicated light level sensor which directly outputs in lux.
Relax tension on the closing curtain brake until bounce detected, then tighten until it goes away.Measuring shutter bounce is easy. Added it to my code during tea-break. None of my repairs have bouncing shutters) so cannot test if the code is correct, looks ok to me, but have no way to test at the moment.
It is running your program.
Yes. A simulated light shining on the sensor.
That is the one in the model. It has analog and binary output pins. The trimmer on the little board sets the on/off switching point.
Relax tension on the closing curtain brake until bounce detected, then tighten until it goes away.
This simulation can do it by turning the light on and off twice.
My kids did some Arduino in High School, but they only borrowed the stuff. So I don't have any of the physical hardware with which to experiment at this time.What ever will they think of next?)
I've never heard of this wonkywiki. I will take a look.
How will you distribute the code to those on PhotoTrio?My code should work fine with a leaf shutter. Hopefully by now somebody has all the bits together and can try.
Have added the shutter bounce code, it simply checks if the second laser is seen again after the second curtain closes. just need to check it works with my own simulation ( a bit of card with two slots cut in it)
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