My car has a camera system installed (video evidence in case of accident). I've been having problems getting the thing automated so it will record when the car is running and shut off when the car is turned off. If I have to hit record then I may forget ti. With this DVR if it loses power while recording the video files can be corrupted so I have to remember to hit stop before I turn the key off - if I forget them the video is lost. (What are the chances I'll remember to hit the stop button if I'm in an accident??)


I built this controller to have 3 key functions:

1) Supply regulated 5v at up to 3A to power the DVR - saves having to use an inverter.
2) Send a 'record' signal to the DVR under certain conditions - Engine on, interior lights on, shock/motion etc.
3) Keep power to the DVR for 10 seconds after the recording has stopped to allow the DVR time to commit the record buffer to the hard drive - prevents corrupted video files.

Once installed it will make the DVR system 100% automatic with no interaction ever required from me other than to plug the DVR's network cable into the network outlet in my garage so I can run upstairs and download any interesting video.

It's a simple resistor/capacitor timer with a solid state relay and a 5v voltage regulator. When I install it I'll have a switch on the dash to set the recording to either Off, Auto (ignition on) or Constant. The alternate triggers (shock/interior lights) can be added later using additional diodes on the trigger input.




This is the controller hooked up to a test harness. The blue and red LEDs represent "DVR Power" and "Record" outputs.

Took about 5 hours total to prototype, test, build etc. Parts ran about $25.

Example video here. Remember that youtube renders the videos down so the real quality is higher. The system has 4 inputs, but I only have the dashcam. Now that I have this controller I can add a 'theif cam' that will come on withthe interior light.

 

pretty neat idea. all cars should have this really, It'd be much easier to find who was at fault in the event of an accident. props to ingenuity

 

I was thinking of doing dvr setup, what components did you use in your system?

 

THe DVR is a cheap ebay unit made by a non-name chinese company. It has 250Gb of HD space and if it record drive time only then I can probably get about 6 months to a year of recording.

The camera is also a non-name color CCD mounted to the same bolt holes as the mirror.

As my car does not have a power seat on the passengere side I'm going to use the power connector for the DVR.

 

Can you post picks of the setup?

 

when I'm finished with the power controller.

I got the controller in and all the connections in place except the power to the DVR - I didn't want to cut up the power cord, but I couldn't find a matching power plug in the 25 or so spare power supplies I have lying around. I'll have to get the plug from Radio Shack tomorrow.

 

Any updates?

 

Yup - last night I built a shock sensor trigger that wakes up the camera to start recording if something knocks into the car. It works pretty well, but would have had the undesired side-effect of having a relay clicking as I was driving (going over bumps etc) so I had to do a quick re-design so that when the ignition is on it deactivates the shock sensor.

I also have to rewire the camera to power on with the trigger instead of with the ignition - and I'm also going to build an LCD "hit counter" that will tell me how many times the shock sensor has been activated - I don't want the camera firing up every minute.

Now that I'm getting the wiring finalized I'm going to start writing up the wiring diagram.

 

Well, the hitcounter didn't work out because both of my 74LS193's (BCD counter chips) are bad, and my 393 (dual 4-bit counter) doesn't have a carry output, so I can only count to 15. I have the 4511 7-seg latch drivers and they work fine, but take a BCD input if I can only count up to 9. If I get back to my car as see the couter showing 5 then does that mean 5, or 15 or 25?


Anyway, instead I rewired the power block for the DVR to also power the cameras and screen - any time the DVR is powered up you can see the video on the screen (if you turn on the screen).

The shock sensor will now wake up the camera AND dvr and will record - the only problem is that the DVR takes 3 seconds to power up and sense the alarm trigger from the shock sensor - so if there is only one shock and that shock trigger output stops before the DVR is fully powered and goes into record mode then the alarm input will not be triggered - so although the DVR has power, it doesn't know to record.

I think the next step is to add a second logic controller that latches the output for 5 seconds, so when the DVR boots and reaches record mode it *does* see a record signal for a short time. Meh, maybe later.

I also removed the power inverter and am now running the dvr directly off the car's 12v, switched through a relay and then run through a noise filter. Removes the need for 100v in my car, and is much quieter without the inverter's fan.

The real next step is to write down the wiring diagram for all of this, including the original power controller AND the shock sensor & shock sensor disable function, and to create a single larger DVR controller that encompasses all of these functions.

The shock sensor's ground-ouput was a swine to add to the circuit board (whic is triggered by +12v), so I just used a relay connected between constant power and the shock sensor ground output - then ran that constant 12v through the switched side of the relay into the dvr controller's trigger input.


The next generation controller will have multiple trigger inputs (for +12v AND for ground-output sensors) isolated by diodes, and it will have power distribution block with multiple ports for power output so it can control many devices (dvr, up to 4 cameras and a screen) and will have pass-throughs for the triggers so the triggers can be used for other things (ie shock sensor connect to factory alarm)

Also, the list of trigger inputs will grow to;
- Ignition on
- Shock sensor
- Manual override on/auto/off
- Factory alarm activated

 

there some sick camers on ebay u hook yo to the plate

 

Version 2 is about to be made... This one will use an etched PCB.






Version 1 has been working great, no problems so far. This new version adds the additional reliability of an etched PCB, but also adds 3 +'ve triggers and 3 ground triggers so I can use the shock sensor and piggyback on the door contact switches without needing external relays.

 

I redesigned the circuit board layout (and added a 10k resistor between the base of the T2 2n3905 PNP and the row of diodes D8,9,10) and etched/assembled it.

In this version RLY1 has been switched to a 12v mechanical relay, and RLY2 will be a standard automotive relay.

The circuit board is nearly complete here, just missing RLY3.



Also, I added 2 more cameras to the DVR. Here's a very short youtube of the second test. http://www.youtube.com/watch?v=RxV20BvCcP4 (video was just uploaded, may be 30 mins or so before it's ready to view) Since this test I have raised and refocused the rear camera and moved the little flag hanging from the mirror. The DVR has 200Gb hard drvie space and will keep 2 months of driving history, assuming 2 hours of driving a day. Adding more cameras has not reduced the time span, but it had 'shared' the framerate with the other cameras. Instead of 1 cam at 60fps I now get 3 at 20. If I add cam 4 (instrument cluster?) then I'll get 15fps.


My first 'outtake' http://www.youtube.com/watch?v=C8MOjJPySpc

 

Version 3 of ther DVR Power Controller is complete.

Full funtion list:

- Zero power consumption while off
- 6 isolated trigger inputs. 3 triggered by +12, 3 triggered by going to ground
- Upon trigger input, controller activates and supplies power to DVR, power to Cameras and sends a RECORD signal to DVR
- When all trigger inputs are off the countdown timer starts
- After 20 seconds the DVR is sent a STOP and power to the cameras is shut off
- After another 20 seconds the DVR master power is shut off

Key features:
- Once triggered, the controller will provide power to the DVR for long enough for it to boot up fully, even if the trigger input ceases during the boot process. This prevents system hang from failed boot
- Trigger input is latched for 20 seconds to ensure that if any trigger input is received the DVR will record SOMETHING even if the trigger is no longer present by the time the boot is comlpete (12 seconds). This is in case the trigger is the shock sensor etc and someone hits the car - I want the DVR to record something, even though it was only hit once.
- The cameras are switched off when the record input signal ceases. This it to prevent the visual motion sensing in the DVR from starting to record if someone walks past the camera during the powerdown cycle. If the motion record kicks in and then DVR power is shut off then the video file may be corrupted.

- Backup battery with power proportioning: There is a small 12v SLAB (sealed lead acid battery) about the size of a digital camera that has enough juice to run the DVR for a couple of minutes. If the DVR is already active when I go to start the engine then the power drained by the starter causes the main battery voltage to drop to 10v - this causes the DVR to reboot, possibly losing video. The backup battery is current-limited with the main power sop it will charge when the engine is running but isolated during the crank cycle. Therefore the backup battery is able to continue to provide 12v to the DVR and keep it alive. This is know int he Carputer industry as "Surviving the Crank"





Since nobody has been replying recently I'm not sure if anyone even gives a crap. I'll post schematics and pictures upon request, but if I get no respoinse to this post then I'll sume nobody is interested and I'll let this thread die.