Help hacking a digital camera.

By the way, powering the camera through the docking station is not a good option for me. The connections are too small for me to tap into, and the connecting jack is not available for purchase by itself. Also, the camera does not record when in the docking station. It will only go into play mode. So I have to power the camera through the battery.

Also, the system does not work without the camera battery. The lithium battery has three terminals. The third probably play a role in allowing the camera to monitor battery life. I have found that there must be a battery in the camera for it to come on. Also, if the battery is removed, you have to reset the date and time, which will be a big annoyance in the field.

Just tried it with 5 volts and the same thing happens. The camera battery slowly dies.

i BELIEVE YOUR PROBLEM CAN BE EASILY SOLVED WITHOUT ANY ELECTRONICS KNOLEDGE BY GETTING A CAMERA THAT CHARGES THE BATTERY WHILE THE BATTERY IS IN THE CAMERA. ALSO I HAVE A CAMCORDER WHERE THERE IS A DUMMY BATTERY LIKE PIECE THAT CAN BE INSERTED IN THE CAMERA AND PLUGGED INTO A NORMAL 120 VOLT HOUSE PLUG AND THE CAMERA WILL RUN INDEFINITELY TILL THE END OF THE TAPE IN IT. THIS IS A SONY HANDYCAM THAT USES MINI DVL TAPES.

vshwn7@aol.com

Hmm.. in my limited experience, signal diodes are just that, designed for signals. Anything more than a few mils will heat it up and perhaps even shut it down. Check the current rating on the diode and check the actual current draw of the system. The other question is why would you put a diode after the regulator? As I recall, the LM can't be hurt by a reversed battery, so I can't see any reason for the diode.

Without the diode the camera battery will power the microcontroller when the main power supply is disconnected (which will occur when the units are stored or transported). I don't want the microprocessor to drain the battery when the system is not in use. So I blocked the flow from the camera battery with a diode. I could simply disconnect the camera battery

Good point about the diode rating. It can handle 300mA, and the camera draws less than 250. So I should be OK. I might try a 1 amp diode just to make sure.

Dear brid0030,

I think the diode may be your culprit. I had some trouble with your "illustration" - could't understand the connections... (you know, there are all sorts of free schematic drawing programs out there - draw it and then copy/paste into a photo/picture editing program and save as a .jpg or .gif. You can then insert your image using the button on the toolbar above !

Try a 1N400x or similar - gives 1A throughput and should keep you supplied with enough current (flow rate).

Let us know how you make out!

Mike

Am I correct in that you're using the 4.25V from your PSU as input to the LM317?

You'll need more than that, as the LM317 needs at least 1.5V between input and output @ 20mA, rising to 1.75V @ 200mA and 2.5V @ 1.5A (all at 25°C). (BTW, this is called the drop-out voltage).

No. I'm using a different power adaptor: 6V up to 2.5A. I was planning on using a 12 V battery in the end, but I may go with 6V batteries if that keeps the heat down on the regulator. A direct test on the regulator output gives 4.1 V.

I don't think you've mentioned this (apologies if you have): the diode itself drops another 0.7 of a volt. You can reduce this by using a Schottky diode (like a BAT85) or incorporate the 0.7V into the design.

This is a bit out of my area but could you leave the original battery in place & keep it trickle charged?

Randal: Yes, that may be the problem. The diode drops half a volt, so it prevents the battery from getting the full 4.1 V.

Nigh: That is what I am trying to do. Keep the battery charged while the camera is working.

If I have the battery fully charged and I run the system without the diode, it sort-of works. Current gets up as high as 400mA though it the camera battery lags behind. The regulator heats up a bit but not too bad. Guess I'll have to add a heat sink and keep experimenting.

Hello brid0030,

Whatever you do your experiments are quite dangerous. At least for camera's battery. Battery for cameras have special design for delivering significant PEAK current (several Amp!). Internal resistance of Li battery incredibly small --- some 0.1-0.01 Ohm. Battery rather is source of current then voltage. So your camera is experienced lack of current and therefore power.

I had a similar experience 8 years ago with photo densitometer. I'd done stabilizer like yours but for 220V power. Densitometer had been turning on and worked in stand-by mode well, but when we were trying to make instrument measurement its gone down. I could realize my PS couldn't deliver enough peak power (no matter volatge). I'd attached radiator to LM and big capacitor. And its began work. But it was awkward unstable device. So then I as you took 2 batteries from old Motorolla (7V) and connected its to dock plug directly. It was my good luck it's eaten 7V and began work for weeks without recharging.

Your docker charger simply has not enough power. Voltage here does no matter. When there is lack of power your camera's battery begins to work for demand of increasing consumption but it wasn't good treated as I assuming logic of your camera getting some "crazy" with yours external circuit.

No matter how high is voltage of your external batteries you have very very low PF. So you need to treat this approach

external battery (3-12V) -> DC/AC high frequency converter -> impulse power regulator (DC) -> dock plug of camera.

Google it or even you can purchase such external battery device with regulator for another cameras. I suppose there are some universal ones even.

Good luck and be careful with it.

P.S. If you're boring to make/purchase new device, accept advice with Schotki diode and try to attach one more set of battery in parallel (not so good practice).

So let me see if I understand this. The camera battery has low resistance, so when I connect leads across it, I am almost shorting out my power supply? That would explain things I guess. However, I just figured out a way to bypass the battery entirely, and current use is the same--about 400mA which is higher than it should be according to the service manual (should be below 250mA).[p/] Since the camera runs without the battery, I think this also means that I am delivering enough power.[p/] The story about the photodensiometer is baffling. You have an item requiring 220V running on 7V?[p/] I just fried a resistor for which I will have to order a replacement, so I am done for a while.

Photodensitometer (PD) it was just my "hacking case". Every such case is featured its features and there is not universal recipe. I'd made powerful dock station instead PD's, it was quick but bad decision as this device was huge and unstable in operation. Then I done bunch of motorolla bateries and took a chance plug its to PD. As it had began work good I stopped my experiments. (PD had not so clever logic to track for its battery state).

Internal resistance of batery virtually measured from charger side is low when battery disharged and higher when completely charged. At the same time completely charged battery has low resistance in consumption mode. It is not easy issue.

If you could find how to run camera without internal battery it's look most better. High frequency switch converter-regulator could be make your scheme very effective. It can deliver needed 4-5V and current on outputs no matter level of voltage of external battery for a long time.

Just buy a new camera that works the way you want it, there is many USB cameras out there for recording continously or a bunch of snapshots every few seconds.

I researched the cameras pretty well. A few details missing from my description:

1) remote field site (no electric, unit must be battery operated and self contained)

2) I want to film birds flying into burrows, and the only way I see to do it is to put a trigger in the burrow and have a means of storing video taken before the entry (thus, the "past movie" feature)

3) I tried the standard game cameras that hunters use to monitor deer and the like--way to slow and the infrared detection works poorly on birds.

4) I thought about using a board camera or something like that to do the recording, but I am far from knowledgeable enough to be able to design the storage buffer and memory circuitry that would allow for something like the past movie feature I have on the casio snapshot camera. If anybody knows of a simple way to do this (i.e. constantly buffer 5 seconds of video and store it on command) I'm all ears.

How far away are you from the target area? Is it primarily in the day or night? Is there a budget that you are trying to stay within? Are you restricted in the space in which you are working in? Is the video going to last for days or weeks on end?

The camera can be mounted virtually anywhere, but most likely it will be below the burrow, near the entrance, looking out in the direction that the bird will approach from. This will (I hope) give a front/ventral view of the bird that will reveal sex specific plumage (so we can tell if it is the male or the female) and any food items being brought in.

I don't have a specific budget, but I want to build about 20 of these devices as cheaply as possible. With my current design, the camera is going to the major expense (about $70 each if I get them used)

I want the recording device to be small because it needs to be near the burrow entrance and should not be a major disturbance to the birds. I plan to mount the camera and circuit board with the microcontroller and voltage regulator (I'm now doing a switching power supply) inside a small waterproof box). The large battery will be external to the box and will be hidden nearby and attached with long leads. The flex sensor that detects burrow entries will also be external to the box. The sensor will go inside the burrow and attach to the microcontroller with long inconspicuous leads.

I would like for the camera to last for two or three days at least. Longer would be better, of course, but with the remote field sites (some only accessible by kayak) I can't be lugging around huge batteries. The birds only work during the day, so I plan to have the camera shut down and put the microcontroller in low power mode at night.

Yes, power switching supply is a clue for your problem. Controller can track battery charging level as well so you need only external battery for your project.

Good luck.

Is there any danger to just letting the battery run down with a switching power converter? I know how to monitor battery power with the microcontroller with a couple of resistors, but I was hoping I could just let the system run as long as it can and get whatever data I can. I have simulated this with the camera, and it switches off when voltage drops below 3.5 volts. The microcontroller does the same thing at a lower voltage (~3 volts I think). Is there any harm in just letting this happen?

Should be no problem.

Good ques. There is no any dangers for external battery as simply your power supply generator shall stop generate impulses. But it means that you get null voltage on power supply output in no time. Therefore your controller program should whether to switch your camera in stand-by mode some early for securing you kayaking in time or once its been switched in stand-by at the same time power supply should be reconnected to reserve small battery directly. This small battery can be internal camera's one. I hope you've rejected your previous idea when two batteries are working simultaneously using circuit you posted.

It's good idea to test everything in laboratory conditions.

You've said that stored date/time is crucial factor for your project. To be honest I've recall it when you asked about "drops below 3.5 volt". You can cope with it also without additional (internal) battery by means of switching external battery directly to camera over turned off switch regulator. Simplest way to add relay at your circuit. But if you prefer a diode decision, it's up to you.

Good luck.

Not sure I understand this. All logged data are on an EEPROM, which will not be affected by a power outage. Also, the camera itself attaches a date and time to each movie it records and all are stored on a SD card. The camera shuts off on its own below 3.5 V, so I see no need for an additional off switch or a diode (remember that the camera battery is now not part of the circuit). I'm useing a Real Time Clock (DALLAS 1307) with the microprocessor with a 3V button battery attached, so I will not lose the date and time when the main battery goes dead.

By the way, what do the blank replies mean? Does it signify agreement with the previous comment? Pardon my ignorance.

Yes, EEPROM and camera attaches time/date. Sorry, I was some distracted with my own problems here. So nothing daunted happens.

Blank replies? Seems to be it's off-topic comments push plus if you want to read it.

Good luck.

Is your external battery a lead-acid job? If so, and you're going to run it 'til it's 'flat', make sure it's designed for deep discharge cycling.

If not, you'd best avoid deep discharge - bung in a switch (relay or solid-state device) so that when your micro notices the voltage getting too low (say 4 - 4.5V for a 12V battery), the battery can be disconnected (to save it from accumulated damage by (possibly repeated) deep discharge).

Thanks John. I'm pretty sure I have deep cycle batteries. also, I've no experience with switching power converters, but I'm not sure that the battery will drain all the way down to 4V before the camera and micro shut down themselves. When I get the parts I'm waiting for I'll see what happens

I think all will be well with that as one of advantages of switching PS is --- it'll simply stop to generate oscillations and, therefore, load the battery when one will be discharged up to controllable desired level.

I'm assuming you'll test everything in lab for adjusting.

Good to know. I've got to take a break from this for a couple of days. I'll chime in with a report when I have some results.

Thanks everybody.

Hello,brid0030

I am not sure is it actual for now, but you could use DC/DC converters like this http://www.peak-electronics.de/english/acdcmodul.html. I'm using one for my project and i do find this stuff very suitable and effective.

Good luck.