Editing Laboratory Preparation (section)

===Setting Threshold===

[[File:CFD_VoltageAdjust.png|thumb|upright=0.85|right|alt=picture of where to stick the probes|Positive lead should go in Red Hole. Negative lead should go to green screw (or anywhere grounded on chassis really). Screwdriver should go in orange hole.]]

'''1. Determining Threshold'''

Adjust the trigger on the oscilloscope until it is a few mV above the Dark Current. 

You want it to be high enough that it is not constantly triggering on the dark current but still low enough that it catches all real events. 

Take note of this trigger voltage and proceed to the next step.

'''2. Setting Threshold'''

For this part, a Voltmeter and a screwdriver must be used. Insert the positive probe of the voltmeter into the hole to the left of the T (in the image the whole colored in red). Ground the other probe on the screw (colored green or any other grounded part). Lastly insert the screwdriver into the hole to the right of T (colored orange). You should get a reading off the voltmeter that changes as you turn the screwdriver. Turn the screwdriver until the voltmeter reads off the trigger current you noted before. 

Note: the voltages you read will be off by a factor of 10 so divide you readings by 10 to get the right number.

The holes labeled z are the DC offset voltage, for our purposes they can left untouched.