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Message |
    
Waynemel
Tinkerer
Username: Waynemel
Post Number: 139
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 22, 2010 - 08:49 pm: | 
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I would like to build a simple shutter speed testor similar to others that have been mentioned on this forum.
I am having difficulty sourcing a photo transistor. All reference numbers seem to be European designations and not easily cross referenced here in Canada. I can order the item from Digikey in the US, but a $20 shipping charge on a 75 cent item seems just plain wrong.
For that money I could buy a completed unit off of that auction site thing (the name eludes me at the moment...E something?)
Anyway, can anyone help? |
Will_inoue
Tinkerer
Username: Will_inoue
Post Number: 26
Registered: 06-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 22, 2010 - 09:30 pm: |
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Can you steal one from an old device like a night light, garden light or old camera (cds)? |
Ron_g
Tinkerer
Username: Ron_g
Post Number: 44
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 23, 2010 - 02:45 am: |
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First class mail to Canada is less than .50 cents.
Send me your address and I will find something that will work for you.Ron G |
Milosdevino
Tinkerer
Username: Milosdevino
Post Number: 12
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 23, 2010 - 04:21 am: |
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this guy, http://www.rusted.free.fr/home.html, (I believe he posts on here sometimes), has a design for a simple tester using a part of a computer mouse.
Check it out. Great site as well, he has done interesting "restorations" on all sorts of stuff. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 140
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 23, 2010 - 04:50 am: |
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Thanks folks.
The idea of using parts from the night lite occurred to me as well, but the voltage may be wrong and I was concerned about response time.
The computer mouse is a great idea. |
August
Tinkerer
Username: August
Post Number: 40
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 24, 2010 - 08:20 am: |
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I have heard that every CD or DVD drive contains a photoreceptor that can be used. Haven't tried it though. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 174
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 24, 2010 - 04:17 pm: |
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Waynemel: the idea of phototransistor from an old mouse (one with ball and rollers, not an optical mouse) is a good one. Other than that, ANY phototransistor with a transparent case will work.
Marek |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 143
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 24, 2010 - 06:25 pm: |
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Thanks for the help.
When I went to my local electronics supplier, they only had phototransistors with multiple pins for use on IC boards. They were reluctant to order anything else as they could not cross reference any of the numbers I had.
Ron_g has kindly sent me an example which should work. |
M_currie
Tinkerer
Username: M_currie
Post Number: 238
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 26, 2010 - 02:05 pm: |
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I did this a couple of years ago with the phototransistor from an old mouse. It worked pretty well. Old ball mice are pretty easy to find these days. |
Der_uli
Tinkerer
Username: Der_uli
Post Number: 15
Registered: 05-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 08:11 am: |
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I simply hooked up a yellow LED with a parallel 100 Ohms resistor to the oscilloscope... it works like a solar cell and generates its own voltage. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 158
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 27, 2010 - 06:52 pm: |
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Ok, thanks to Ron G, I have built myself a shutter speed tester. However, when using Audacity, I am not getting any spikes. The wave is just a series of very shallow squiggles.
I am just pressing record and very briefly shinning a flashlight on the sensor.
What am I doing wrong? |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 276
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 27, 2010 - 07:57 pm: |
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What is your circuit? Also, do those squiggles change if you break the circuit, i.e. are they being seen only when the circuit is complete? If they are visible even if your circuit is not complete, or closed, then something is wrong and the signal is just noise. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 159
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 27, 2010 - 08:25 pm: |
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The circuit I am using is here: http://www.baytan.org/prak/shutter.html
The only difference is that I added a switch.
The squiggles were constant and therefore noise.
I have done some further testing and did get it to work, however, it is a little strange.
I have to use the "line-in" input on my computer and set Audacity to "aux, line-in 2".
Using the mic input does not give a signal.
Also, the switch on the tester must be in the off position. This makes no sense, I know, but I'm sure I tested the switch and marked the proper "on,off" positions.
I'm just happy that it is working, so I won't ask too many questions!
I tried the outfit with different light sources and it works fine and seems to be very precise. I even tried a TV remote and it shows a very strong signal, however the signal is in pulses, so I don't know if it would be easy to measure the duration. |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 277
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 27, 2010 - 10:15 pm: |
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You probably mislabeled the switch. Where is your switch in the circuit precisely?
Yes, determining the proper input for your card is sometimes tricky. But once you know which input works, it is quite consistent.
Remote controls usually emit pulses, as you discovered. A constant source could be better. Some video cameras have this night vision mode which is basically infra red light. If you have one, try that instead. But usual LED or incandescent lamp flashlights should work as well.
It also helps to try the maximum sampling frequency of your audio card. I usually do this at 96 KHz.
Determining speeds faster than 1/1000 s is mostly tricky. Remember that the signal coming into your card is dc filtered. So if the voltage across your audio input changes, you will only see a spike (the new voltage won't stay at the new level) and the wave form will eventually do down almost zero. This means that at slower speeds, you will see two spikes in opposite direction. At 1/1000 s and faster speeds, the slope of the spikes curves is too shallow to make a reliable demarcation of the shutter opening and closing. This can potentially be improved by restricting the photo detector's receptive area with mask with a sharp hole, but I haven't tried this yet.
Feel free to ask questions. That's what this forum is about!
Good job! |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 160
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 28, 2010 - 05:26 pm: |
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I placed the switch between the positive battery terminal and the phototransistor.
Yes, upon further inspection, I misread the markings on the switch and labelled it wrong. I checked the resistance of the switch this time just to make sure I wasn't loosing my mind.
I'm still not sure why my mic input does not show any signal. |
Ron_g
Tinkerer
Username: Ron_g
Post Number: 48
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 29, 2010 - 03:33 am: |
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The mic input has a volume control slider that I set at about 50% and adjust as needed.I am sure that you know this but I fought with it for a while before I figured it out.The mic circuit on some audio cards has a boost circuit that can be enabled and that can help with your signal amplitude as well.I don't mean to question your competence but sometimes it is the most obvious things that throw us.Ron G |
Papco_instruments
Tinkerer
Username: Papco_instruments
Post Number: 4
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 10, 2010 - 10:06 pm: |
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Hello Everyone
Please keep in mind that a fully self contained shutter speed tester is still available.
Visit www.papcoinstruments.com for information.
Thanks
Paul |
