The simplest form of interfacing is just to wire it (via an optocoupler) into a DS2423 and count the pulses. However, this does not (apparently) adequately distinguish between manmade interference and natural lightning. The difference can be discerned by looking at the duration of the pulses.
According to patent 5,977,762, the detection is of natural lightning if either the number of strokes is high, or the total duration is large. Accordingly, I present the circuit below. Note that I don't think that this circuit violates the patent as the patent requires that counting the number of strokes and their duration is performed by starting a timer when the first stroke is seen. The standard way of running 1-wire devices is to poll them at regular intervals. Hence there is no timer that is started by the first stroke.
The power for the board either comes from a hub, or directly via a jack and regulator.
There is a fair amount of protection in the form of TVS and diodes on the inputs. This is all to try and prevent things from blowing up badly!
The circuit is available in a PDF file.
I have prototyped the circuit using my experimenter's board plus a bit of breadboard. The original experimenter's board only counted the number of strokes, and I felt that it was a bit of a waste of the second DS2423 channel!
Actually I now realize that there is a potentially serious problem - very short pulses will not get counted and will be eliminated by the debounce circuitry within the DS2423. In particular, a pulse shorter than the debounce time (400usecs) will be ignored. This is a side effect of making the pulse 'active high'. The reason for that was to directly connect it to the reset line of the 555. Maybe I can just claim this as a feature!
Back to the main sensors page.