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Message |
    
Hobbes
Tinkerer
Username: Hobbes
Post Number: 2
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 15, 2009 - 07:10 pm: | 
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On several other websites I've read about the DIY sound card shutter, and I decided to try it for myself.
I don't have any prior experience with electronics, but the tester looked simple enough to build, so I actually built two of them based on two different designs. (Here are the websites that have the designs: http://www.davidrichert.com/sound_card_shutter_tester.htm and http://baytan.org/prak/pic/shutter-speed-circuit.jpg.)
I think I've made all the connections correctly, but I can't get either of them to work.
I'm using the device with the Audacity freeware program on a MacBook Pro. (I used Audacity to record some material from my Ipod via the microphone jack just to make sure that the program and my microphone jack were working.)
Does anyone have any suggestions for me? Are there some settings on the software I need to fiddle with?
Thanks |
M_currie
Tinkerer
Username: M_currie
Post Number: 161
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 15, 2009 - 09:29 pm: |
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I did it once, and mine worked, though not spectacularly well. The waveform is pretty sloppy, and usefulness declines as shutter speed rises. It's very good on slow speeds. Since you have already tested the computer end, I'd make sure all your polarities and connections in the tester are correct, try switching them around even if you think you shouldnt, and if that doesn't do it, try another phototransistor. I robbed one out of an old mouse for mine.
Don't forget too that the signal is probably going to be pretty weak, so make sure you crank up the gain in your sound input. |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 147
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 16, 2009 - 02:21 am: |
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If the input of your sound-card is very high impedance or ac coupled (i.e. through a capacitor) I don't think the first circuit can work because there will be little or no current through the transistor. I think the second circuit should work, but you may not need the capacitor. I use my own version http://www.ydo.abelgratis.co.uk/shutter_tester.html with Audacity and a Creative sound card. |
Hobbes
Tinkerer
Username: Hobbes
Post Number: 3
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 16, 2009 - 10:50 am: |
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Thanks for the suggestions, M_currie and Steve. I think I'm getting somewhere now with the first device I built. It does look like it's a problem with signal strength. I boosted the gain in Audacity and I boosted the input volume via my Mac's system preferences for sound. I started to get a weak signal when activating the device. The waves in Audacity were hard to read, so I went to Preferences -> Interface and changed the "Default View Mode" to Waveform (db). This was much more readable.
I've been using a single AA battery in the device. Would I get a stronger signal if I used two batteries?
By the way, I tested the shutter speeds on my Nikon FM2 up to 1/500 of a second and the readings are pretty nearly spot on.
Thanks again. |
Hobbes
Tinkerer
Username: Hobbes
Post Number: 4
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 16, 2009 - 01:36 pm: |
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I took Steve's advice and got rid of the capacitor in the second version of the tester. Now it works with a very strong signal. |
Lucas
Tinkerer
Username: Lucas
Post Number: 90
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 17, 2009 - 05:04 am: |
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A friend built me one, so I cannot help you with the internals. He incorporated a LED as a lightsource in the circuit and that is much nicer than fiddling around with an external lightsource.
http://farm4.static.flickr.com/3113/2754080480_dd2da23ede_o.jpg
http://farm4.static.flickr.com/3216/2753249591_de436a31a5_o.jpg |
