26 



B) Two wires should be extending from the solenoid. 



1) Solder one wire to the junction of the 220 ohm and 470k 

 ohm resistors. 



2) Solder the other wire to the collector on the transistor. 



C) Wire the unijunction accelerator switch as explained on pp. 

 15-16. 



Attaching a Spore Trap to the Instrumentation 



Materials 



(1) length of two-conductor wire 



(4) 'quick-disconnect' wire connectors 



Instructions 



It may be desirable to attach to the leaf wetness indicator a 

 spore trap or other device that will be activated only during periods 

 of leaf wetness. This can be accomplished very simply when the 

 sensor relay is being wired. The sensor relay has 4 pairs of prongs. 

 One member of the 2nd and 3rd pair have already been wired (see 

 'Wiring the Relay', p. 11). To attach a spore trap, wire the other 

 member of each pair by repeating step 3 under 'Wiring the Relay.' 



1. Attach 'quick-disconnect' wire connectors to the ends of the 

 copper and silver strands of each speaker wire lead that is 

 extending through the PVC 'T'. One lead will be attached to 

 the spore trap and one lead to a battery. The leads should be 

 labeled so they will not be confused with other leads extend- 

 ing through the PVC 'T'. 



2. Cut two lengths of two-conductor wire that will extend from 

 the sensor to the spore trap when it is positioned in the field. 



a. Attach 'quick-disconnect' connectors to the strands at one 

 end of each wire. They will connect to the leads extending 

 from the PVC 'T'. 



b. The leads at the other end of the wires will be attached to 

 the spore trap and the battery. 



NOTE: If a spore trap is to be used, it may be necessary to 

 include an additional battery to meet the power require- 

 ments of the spore trap. 



