I have been using a digital still camera to take time-lapse photos....one photo every 60 seconds. I built a timer using a 555 which uses pin 3 (out) to activate a small 5 volt relay with a diode across the coil. The camera originally ran on 4 AA cells, but a 6v gell cell now powers the works.
This camera is triggered via a simple pushbutton switch which I soldered wires onto that go to the relay. (the camera does not go to sleep in this short of time)
Appearently this all draws more current than I would think 'cause my gell cell barely lasts 6 or 7 hours before running out of voltage and the camera shuts down.
So in an effort to reduce total current draw, the 555 is being replaced with a 7555, and in the same vain, I now think I should be replacing the relay with an optocoupler of some kind.
The 7555 easily lights an LED (for the 0.5 second or so trigger time), but I am not up on all the different opto's enough to know what to pick to act like a button push to my camera.
I would like a suggestion or 2 on where to start here, even some part numbers if someone has already done this.
No, there's no timer mode......and as far as investing in a camera that does have.....I have 10 of these things working that I use in forest plant research....I'd rather invest in some timer mods than new camera equipment.
I don't blame the 555 totally (or even the relay) but am going to reduce current draw where I can.
Got any suggestions or part numbers for my opto question?
You think it's the *555* that's responsible for the current draw? Yoicks.
Hm, or you could read the manual for the camera and see if it has a timer mode. Or just buy a camera that does because you're getting into "waste of time and effort:already been done" territory.
Thoughts.. A) Stay with relay. Use minimal ON time wave. Purchase very low draw relay. (Telecom relay?) Maybe use CMOS 555 version. Power it up with an adapter.
B) Search Digikey, Mouser etc for 4 pin opto. (Designers generally won't shop for you on this one.. It's too basic.)
Try something like the PAA110, LAA110, or other similar MOSFET relay IC. They will operate on less than 5 mA and provide the dry contact closure you need to trigger your camera. Good luck!
Just curious, How much current is it drawing with and without your mods? What is the amp hour rating of the battery? Even a bipolar 555 should be drawing less than 20ma. CMOS should get that below 1ma. More than likely you can replace the relay with a mosfet and use less power than an opto.
Mike
"In view of such harmony in the cosmos which I, with my limited human mind, am able to recognize, there are yet people who say there is no God. But what really makes me angry is that they quote me for the support of such views." Albert Einstein (theoretical Physicist)
On Thu, 03 Jan 2008 14:25:08 -0500, Jim wrote: On Thu, 03 Jan 2008 14:25:08 -0500, Jim top-posted: [Top Post Repaired]
If this wraps, just reconstitute it in your browser window.
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But probably the worst culprit is the camera itself - I have a Fuji somethingorother, it was $139.00, which was the cheapest cam at the time; it eats batteries in a matter of days, even when it's not on.
If you can power down the camera completely (i.e., disconnect the battery) and don't need to set the clock every time you turn it on, you might be able to shut down power to the camera in between shots.
I can't do that with my cheap Fuji - I take the batteries out, but then when I turn the camera back on for the next usage, I have to reset the clock before I can snap a picture. I figure it's worth it, to have a set of batteries last more than a day or two.
You should measure the current, but I guess the camera is drawing the most current, because it does not go to sleep. The relay should draw no current, too, if you use one which are triggered with pulses and locks to closed or open position without continuous current flow.
Maybe an idea would be to use 2 relays: One for switching the main power on/off and one for triggering the push button.
But why do you use a relay? A mosfet should work, too, for both, the camera power and the trigger. First the camera should power up. Some seconds later (depends on your camera, how long it needs to startup) the trigger can be pressed and again some seconds later (depends how long it needs to save the image) you can power it down. If the power up sequence doesn't need much power, it will work some more hours.
The sequences could be implemented with a small microcontroller, or just a
4017, which is clocked from the 555 every 6th second: You'll get 10 different outputs, at second 0, second 6... second 54. E.g. you could use
0, 6 and 12, or'ed together with diodes, for power up and 6 for the trigger.
--
Frank Buss, fb@frank-buss.de
http://www.frank-buss.de, http://www.it4-systems.de
I've built a digital time lapse camera using a picaxe for a timer.
The camera takes a fair amount of power while just sitting there waiting if it is in an active mode. To conserve the battery (two AA cells) I put the picaxe to sleep between shots where it is burning power in the microamp range. It wakes at a predetermined time set by a series of switches, and sends power to the camera via a mosfet (instead of a relay) and allows the camera time to come on (initialize its own processor) then takes a picture, stays on for a time period to allow the camera time to store the picture in flash memory, then goes back to sleep removing power from the camera.
A set of AA batteries is good for three outings with the camera and each use is good for 60 pictures over a time period of up to 5 hours. So about 180 shots and 15 hours of operation from a pair of AA alkalines.
You could do something like that with two or three cmos 555 timers - one timer gives the long delay between shots a second operates the shutter after the camera comes on (three timers would only serve to make the adjustment a lot easier if you want to change the delay interval without a lot of tinkering)
If you are working your camera by supplying power via a USB connection
- you're wasting a lot of power - the advantage is that it keeps the camera active rather than powering down, so only takes one timer to make it a time elapse camera, but it was really designed for an unlimited power source so they don't take pains to conserve power.
I'm in the process of building "camera two" and it will take between
900 and 1200 pictures on a set of batteries, and shut down if the ambient light is too low (daylight only). I plan to run it unattended for a week on a pair of D cell batteries.
If you have rudimentary or better BASIC programming skills, the picaxe is only $3 and can be programmed with only a serial cable from a PC and three resistors. They are loads of fun to play with. 3-A/D converters built in, four input output ports on a power miser 8 pin dip, and a lot of neat programmed in capability, (PWM outputs, 20 ma drive capability with totem pole outputs, servo outputs, music , infrared remote control encoding and decoding). "Camera one" cost me about $20 total ($9 camera) "Camera two" will cost about $25 (with a $19 camera) Waterproof box may cost more than the works inside.
Hey- are you using something like this for the "gell cell?"
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Cuz if'n you are then that puts your current draw way up at 750mA, which is way beyond any re-work of your extremely poorly described 555/relay combo will fix-unless you really goofed up with the relay selection, speaking of which, the 5V job will not take to 6V very well. You should be using something like this:
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That one has a 150R coil for 5/150=1/30=33mA current draw from 5V, and that is while it's being powered. Is your timer configured so that it times out 60 seconds and then *pulses* the relay for 50msec or so before it turns it back off and restarts the next 60s duration? If so, that puts your average relay current draw at 33mA x 0.05/60=0.00002Amps, quite a small number, and also makes the relay much more tolerant of your 6V supply.
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