|Solar Charge Controller||Solar Power Center||Dark Activated Switch||Low Voltage Disconnect||Battery Voltage Monitor|
The 2N3904 drives the reed relay, which in turn triggers the camera's electronic shutter switch. The VN10KM prevents the circuit from triggering the camera when it is first turned on. The LM324 GND Ref circuit divides the 9V power into two for a 4.5V ground reference. The other op-amp circuits use this reference value.
When shooting through an SLR camera, this circuit should only be used at night. Daytime use will cause it to retrigger indefinitely because the SLR's viewfinder goes black then bright when the photo is done, this restarts the detector.
For daytime use, it may be preferable to mount the photodarlington transistor in a black tube, the tube should be cut to a length that gives the transistor an angle of view that is similar to the camera lens setting. The back of the tube should be covered with something black to block light from the back side.
The camera setting depends on the model used, I have taken many good shots with a Nikon N2000 camera in auto-exposure mode. A newer Nikon N70 responds too slowly in auto-exposure mode, try using a manual exposure mode with a tight F setting and a long time duration. A digital camera is ideal for this type of operation since you don't have to pay for film. Unfortunately, only high end digital cameras tend to have external trigger inputs, and many suffer from a very long delay between when the trigger is pressed and until the photo is taken. The use of manual exposure settings may improve the speed of the camera. One reader has reported success using a Canon Digital Rebel EOS camera with this circuit.
When dealing with large thunderstorms, lightning strikes often create a conductive path, then strike multiple times through the same path. This type of strike is the easiest to photograph. The most difficult strikes to catch are single zaps in the daytime. Daylight photos require short exposure times, lowering the chances of a zap being caught on film.
When using this circuit, be prepared to run through a lot of film, a good storm can empty a 36 exposure roll in just a few minutes. Typically, around half of those shots will be good when taking nighttime photos. Different storms have different "personalities", some will produce a lot of quick zaps, while others will light the sky up in an almost continuous manner.
When using the circuit, be sure to stay away from sources of flickering light such as street lights and fluorescent lights, they will cause false triggering. It is normal for the circuit to activate constantly when in the presence of indoor lights. I recommend testing the circuit by shining a flash light across the detector in a completely dark room.
If you get any good photos using this circuit, I would love to see them.