Public Lab Research note


Shutter timer upgrade

by cfastie |

Read more: publiclab.org/n/2785


After walking around like a fool for an hour towing a kite lofting the cameras that were not shooting because the timer battery had died after 13 minutes, I decided to try Randy Sargent's modification of the MK111 timer. Randy's suggestions are described in the later comments on this note. The modified timer works as expected!

The idea is to build the timer kit without the relay, or remove or disconnect the relay from an assembled timer. Then two wires must be added. The timer then runs on only 6 volts (instead of 12 to 24v), and requires much less current to operate. So a much smaller battery can power the whole thing for a long period. As originally designed, two batteries are required (one to power the timer and one to provide power signal pulse to whatever the timer is controlling). With Randy's mod, just one battery does everything.

I have not done endurance testing yet, but I think a fresh 4LR44 six volt battery should last plenty long. Other 5-6v battery packs will also work. For example, it runs on 4 AAA alkaline batteries. It does not run on 3 alkaline AAA (4.5v) or 4 NiMH eneloop AAA (which are only 1.2v apiece). The 4LR44 is tiny and lightweight, so I hope I can get several hundred shots out of one.
[Update: The power supply I use regularly with this timer is 4 AAA alkaline batteries.]


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3 Comments

cool! the 6v signal isn't a problem for the cameras? USB is usually 5v or lower. if there's a problem, you could put a few diodes in the line to drop the voltage (dirty, inefficient method, but convenient).

makes me want to pull out my 555 and get cracking again!

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Yes, I must be right at the limit for voltage that the cameras can tolerate. One of the diodes on the MK111 (D3) apparently drops the voltage from 6v to 5.5v, so we are not too far off. The cameras seem to work fine with the new timer setup, but I still want to do some more testing (maybe with an old camera!).


cool. if it's a problem, grab a few 1N4001 (or 1N4002,3,4...) diodes from radioshack or any electronics store, they're handy to have around for just such a quick fix.


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