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Need a timer to trip my shutter

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mailrail

New Member
First time poster; full time idiot.

I am attempting to build a timer circuit that I can use to trip the shutter of my digital camera for use in Kite Aerial Photography. I've finished running wires from the battery and shutter of my camera and I tried building a circuit that I found on a KAP site, but it doesn't seem to work for me. I've been using a TLC 555 timer so that I can tap off of the 2 AA batteries from the camera. The circuit that I've tried is at:

www.rtpnet.org/robroy/KAP/rig1.html... all ears (or eyes). Thanks for help! :D
 

nettron1000

New Member
I'd first like to say i think thats in ingenious idea with the kite mounted camera. Ive done alittle amateur photography myself in the past, but ive never thought of doing that.

I just took a quick look at your schematic and noticed that the LED is backwards but it appears to me that the reason its not working is because you are trying to drive a 5 volt relay with a 3 volt power supply. This usaully wont work but there are some 5 volt relays that will work with 3 volts, but these are rare exceptions.

My advice is that you should power the 555 timer circuit from a separate 6 volt battery pack. You can get these at Rat Shack that can take four AAA batteries. These packs are very light weight and wont add much weight to your set-up.

Ive re-drawn your schematic from a circuit ive just finished testing and it works fine. Note i used a 6 volt battery pack power supply. You could also try using a 9 volt battery.



Just one question, why are you using a 5 second shutter time ?
 

Roff

Well-Known Member
I agree with Nettron1k's comments. I'll add a few more:
If you reduce the shutter time, eliminate the LED, and use a CMOS timer (as in the original), your batteries will last longer. You can reduce the shutter time by making the resistor between pins 6 and 7 a lower value. You can increase the time between pictures by making the resistor between pin 7 and VCC a larger value (which will also save a little power).

You can get a 3 volt relay from Digikey, but I'm not sure the 555 can drive it directly with a 3 volt supply. think Nettron1k's idea is better, unless you can't tolerate the weight of the extra batteries.
 

mailrail

New Member
Thank you VERY MUCH for not only taking the time to reply, but taking the time to draw the schematic. According to the original schematic, it was supposed to be off for 30 seconds and on for 5. I would actually prefer something in the neighborhood of a shutter trip once every 60 seconds. What is your circuit set for?

Also, it's been YEARS since I did any electronics-type work or soldering (I put in 1 year at a DeVry school in the early 80s) and I've NEVER worked with a reed relay before. I was a little confused about which of the 4 pins were the inputs, etc. How 'bout a quick tutorial with those?
 

mailrail

New Member
Oh yeah...and weight is a HUGE consideration here. I'm not sure I can handle 4 AAs on top of the camera and rig weight. One 9-volt, maybe.
 

seeker

New Member
Hi mailrail,
You should be able replace the relay with a transistor unless I'm missing something here :?:
 

nettron1000

New Member
I'm not sure I can handle 4 AAs on top of the camera and rig weight. One 9-volt, maybe.
If you re-read my post you'll see i said AAA batteries (triple A's) they are smaller and lighter than AA batteries ( Double A's). If the weight is still too much then you'll have to go with a 3 volt relay as Ron already suggested.



Thank you VERY MUCH for not only taking the time to reply, but taking the time to draw the schematic. According to the original schematic, it was supposed to be off for 30 seconds and on for 5. I would actually prefer something in the neighborhood of a shutter trip once every 60 seconds. What is your circuit set for?

If you take a look back at the schematic you'll notice ive editted it to match the components in your original schematic and ive also labelled the timing components so you can follow along with the calculations below.

You can find these formulas via a simple search on Google but i'll show them here along with my calculations to make things alittle clearer.

Pulse high time T1 = .693 (Ra + Rb) C

= .693 x (220,000 + 47,000) .0001

(Note that the resistor values have bin changed to OHMS and the capacitor value has bin changed to FARADS.)

= .693 x 267,000 x 0.0001

= .693 x 26.7

= 18.5 seconds high

This is how long the relay will be "off" and how long the LED will be "on", indicating that the output is in a high state.
But like Ron suggested theres really no need for the LED other than monitoring the circuit. For a longer "off" timing interval simply change Ra to a higher value and plug it into the formula above.

Now to calculate for the low time T2 = .693 x Rb x C

= .693 x 47,000 x .0001

= .693 x 4.7

= 3.257 seconds low

This is how long the relay will be activated , the relay contacts are closed and the shutter is engaged, the LED will be "off" indicating a low state at the output on pin 3. I dont think this length of time is really necessary which is why i asked about the 5 second shutter time.

My advice is that you should replace Rb with a 2.2 K resistor . This will shorten the length of time the relay is activated and save on battery life as Ron also suggested.
 

mailrail

New Member
Sorry Nettron, I saw the "AAA" right after I had hit 'send' on the prior message. I think I can live with the weight of the 4 AAAs as long as I have a strong wind. I may have to go with a larger kite, but I've wanted one anyway; it'll just be an excuse to go and buy one. I'll tell my wife that YOU said so. :wink:

Not that I really knew what I was looking for, but I put an VOM across the relay in the original circuit that I built and saw that it was "pulsing" at just about what you've calculated (was counting in my head). I can accept 18.5 seconds although I'd really prefer something a little closer to a minute. If I replace Rb with the 2.2K as you suggested, could I then replace Ra to lengthen the "wait" time, too?

And again, I'm still a little confused about the relay and lest you think I'm lazy and looking for a way out, I searched and searched the internet yesterday (as well as my local library) but couldn't find anything which explained much about the pins on the relay. The back of the RatShack pack illustrates the two pins on either end as being the actual switch and the two pins on the sides as the coils. (Try to hold your laughter here, please) I'm assuming that the "end" pins are the ones I run to the shutter, is this correct?

A couple of other points of confusion (remember, it's been a while since I tried any of this) is the NE555 timer that you've drawn into your schematic. Is this the same as a TLC555? And are you using 2 LEDs or just one? There's a "D1" listed as well as an LED. Okay, this is the point where you roll your eyes, throw up your hands and then bang your head on your keyboard.

Thanks for any and all help you can provide.

Sully
 

nettron1000

New Member
If you you check out this link it shows a pictorial wiring diagram of how to connect up your reed relay to a camera.

http://www.jesseshuntingpage.com/rs-49-425.html

Its near the bottom of that page, the red and black wires are connected to the coil and the green and yellow wires are the normally open contacts which go to the camera.




A couple of other points of confusion (remember, it's been a while since I tried any of this) is the NE555 timer that you've drawn into your schematic. Is this the same as a TLC555? And are you using 2 LEDs or just one? There's a "D1" listed as well as an LED.
The NE555 is pin for pin identical to the TLC555, its just that the TLC555 is a CMOS low power type, which obviously would be better in your case if you want low power consumption. I used the NE555 cause a didnt have a TLC.

D1 is just an ordinary diode not an LED. I used a 1N914 switching diode, but just about any diode will do. Its only purpose is to protect the 555 timer from inductive kickback spikes from the relay coil.



Okay, this is the point where you roll your eyes, throw up your hands and then bang your head on your keyboard.
No , this is where i go to plan "B".

"Ron i need your help here !!!"

Just kidding ! Hope this helps.


Net.
 

mailrail

New Member
Thanks Net. You've been MORE than patient with my electronic ignorance.

I've been to that website and have seen that pictorial diagram but must have looked right over the reed relay part. Thanks for pointing it out to me.

I'll be building YOUR (<------- giving credit where it's due) circuit sometime this week. If winds (and my work schedule) allow, I'll test everything out later in the week. Hopefully I'll be able to post a picture or two of my results here for all to see. Thanks again.

Sully
 

nettron1000

New Member
Great, keep us posted (literally) on your progress and yes i'd really like to see some of the resulting photos.

Best of luck.






Net.
 
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