Frequency Counter, Duty Cycle And Dwell; Automotive Rpm; Logic Analyzer - Extech Instruments 381285 User Manual

FREQUENY COUNTER, DUTY CYCLE and DWELL
1. Insert the black test Lead into the negative (COM) jack and red test lead into the
positive COUNTER jack
2. Turn the rotary switch to the Freq. Counter position
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3. Press the F1 Frequency key to measure and display the frequency.
4. Press the F2 Duty to see the Duty Cycle in percent and the Dwell Angle in
degrees.
Press the RANGE key to change the number of cylinders.

AUTOMOTIVE RPM

1. Insert the black test Lead into the negative (COM) jack and red test lead into the
positive COUNTER jack
2. Turn the rotary switch to the RPM position
3. Connect the inductive pick-up to the meter and clamp the secondary ignition wire of
the engine
4. Press the F3 rpm(1) key for distributorless electronic type engine (2 stroke/DIS) or
the F4 rpm(2) key for conventional 4 stroke distributor type engines.
5. Read the rpm on the display.
NOTE : To avoid interference from noise or outside sources, keep the meter away from
spark plugs or coil wires.

LOGIC ANALYZER

WARNING : To avoid meter damage, never measure signals greater than 40V dc when in the
Logic Analyzer function.
1, Insert the black test lead into the negative
(COM) jack and the red test lead into the
positive SCOPE input jack.
2. Set the function switch to V and change to
"dc" with AC/DC key.
3. Press the LOGIC key.
4. Read the voltage and frequency, timing
chart.
Press F1 Restart to start the logic chart.
Press F2 to select a rising or falling
trigger slope.
Press F3 Time/Div to change the sweep time.
Time divisions will vary to display the
best wave pattern in the autoranging mode or they can be set manually using
the arrow keys.
Press F4 RANGE to select the logic type. Select from TTL, 3V CMOS or 5V CMOS.
5. Press the LOGIC key to exit logic function.
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