Rain Detector Working

[Tom Droege <tdroege2@earthlink.net>]

I now have a working rain detector that closes the dome when it detects 
rain.  Due to the kludgey nature of my QBasic software, it only senses the 
rain detector part of the time.  So it can be as much as 70 seconds after 
it sees water before it closes the dome.  Sigh!  At some point I will 
switch over to better linux software.

Rather than design something, I bought an $8.95 water detector kit from JDR 
MIcrodevices.  It is a very simple circuit.  Water detected between two 
contacts starts a 555 oscillator.  This is hooked to a speaker and makes a 
terrible noise.  I rectify the speaker signal and feed it into one of the 
ADC channels of the Mark IV.  I should be able to detect this with the 
interrupt loop that runs in the Mark IV, but if I try to read an adc 
channel on the once a second interrupt, the RA drive starts going full 
speed forward.  I am not going to try to figure out that one.  Instead, I 
will wait for a debugged system from Rob or Michael^2,

The rain detector sits at the neck of a sawed off gallon water bottle.  It 
should not take much rain to cover the detector and start it going.  The 
problem is stopping it - drying it out after we test it.

Tom Droege