On a school project to run a camera on time lapse from the arduino I am having an issue powering the device. I found that according to the manual it requires up to 2.5Amps at 3v (x3 AA), this is I believe is way beyond what the Arduino can supply.
So I sourced a voltage regulator the LD1085V which I am feeding directly with x6 AA 2800 mAh batteries (around 8v I want to power everything of x1 power pack) into the DC connector on the camera. by the way I know this is more an electronic issue but I didn't really know where else to ask and hope you guys can help.
Using a R1 240ohm & R2 390 ohms the voltage is varied to around 3.28v but very strangely the camera does not seem to have enough power to start it tries and fails. My guess is the problem is to do with how many amps it is drawing (testing showed it draws 1.28 A on startup but its too quick to read the spike) but why the LD1085 supplies 3Amp? what am I missing, do you need a much higher input voltage to make it supply 3 Amp? and is there an equation for this.
I have added the recommemnded 10uf capacitors for stability, but the camera just will not start up (screen flicks on for a split second then goes off) in fact if you insert bateries into the camera to stat it then take them out while the DC connector is inserted the camera will stay on until you try and take a picture, then it looses power again and shuts down.
Its really frustrating, I look forwaed to your comments, bearing in mind I am very new to electronics so go easy please
So you want to feed the regulator with 8V and get 3V out, burning 5V at 3A.. right? This will create quite some thermal loss. I would suggest to feed the regulator with a lower voltage, if it's a low drop (1.3V?) than 4.5 volt would be enough.
I also think the 10µF condensator is only there for some noise canceling. Try some bigger models, 2200µF or 4700µF are common values for power supplies.
Errr I am confused now, why is the camera not powering on though guys? is the setup ok in theory? if so could it be the connections that are the problem?
I can try a lower voltage but why would that be more likey to work?
Looking at the regulator data sheet, the resistors are used for adjusting the regulator output voltage. You probably could use a small trim pot from radio shack to make the output voltage easy to adjust. You need to measure the battery voltage when the cam tries to move, as the battery may actually be discharged and going low under load. Measure the voltage out of the regulator when the cam tries to move and see if the desired voltage is maintained.
Ok so I tried x10 AA batteries next, the camera turns ON but boy does it get HOT, it melted an ice cube in a plastic in about 3 seconds and eventually shuts down, but the camera does work well for a good 20 seocnds or so.
Swaped LD1085 for cool one
The x6 AA pack is the same, so yes it doe seem the thermal heating is switching the camera off. The camera though does not work as long though.
Swaped LD1085 for cool one
Now x4 AA batteries on the lower voltage as recommeded, well the camera will not start at all, the screen flashes briefly and then fails.
Whats going on I don't get it? (by the way I found a spare 1000µF (I don't have many bits) which I also added. It seem this way is not going to work, but I would love to know why? could you explian what going on please? to me it looks like the higher voltage powers the LD1085 better for higher mAh output but gets so hot it shuts down, while the lower voltage does not provide enough mAh, would get hot if the camera operated long enough, am I right in thinking this?
You are trying to burn off too much current in your regulators coupled with the fact that your batteries are struggling to provide that much current. The higher the voltage the more power you burn and the hotter your regulator gets. If you lower the voltage there is not enough excess voltage to regulate correctly.
How to fix?
Use better batteries the AAs are not up to providing more than about half an amp current unless they are the rechargeable ones.
could I also ask the batteries are 7dayshop Ni Mh 2700 mAh should this not mean they can deliver 2.7 amps? or I am horribly wrong to think that? (can't find them on that site previously mentioned)
We stayed clear of the switched regulators as weight is an issue as this camera is flying in a weather balloon.
Not necessarily, the capacity of a battery is related to the maximum discharge rate by the so called C value. If a battery is rated at 15C it can supposedly pull 15 time the capacity out. But you will not get the full total of amp hours at this rate.
The batteries you are using do have a much higher discharge rate than a normal primary battery though. You have to establish what voltage and current your camera needs, I haven't seen that figure yet. Until you have that you stand little chance of a decent design. Measure the current it is taking during the 20 seconds or so it is working.
for there weight and the ability to cope with extreme tempreatures
With the switched regulator do you think this will work with these batteries?
if not I'll go back to powering the camera seperate to the Arduino system, we just wanted to make everything power of x1 battery pack you see, hopefully saving weight.
that is hot