Calibration Instructions
The SPD -100 and SPD -100L tachometers are normally factory-
calibrated to the customer-specified number of sensing teeth or
discontinuities, sensing speed, and desired numerical display.
If necessary, refer calculation procedure below to
Calculate Signal Frequency and Gate Time.
To calibrate an SPD -100 or SPD -100L
1.
Remove the sealing plug on the back of the housing.
2.
Apply the calculated signal frequency to terminals 1 and 2.
A Dynalco F-16 or F-15 signal generator is ideal.
3.
Select the appropriate gate time range on the 4-position switch.
See label on back of SPD-100 or SPD-100L; or refer Item 3.
4.
Adjust the vernier potentiometer for the desired display.
See below.
Example:
If 3390 Hz = 1800 RPM, then gate time is 0.53 seconds.
1.
Apply 3390 Hz to terminals 1 and 2 on tachometer (no polarity).
2.
Turn the gate time range switch to (either) position number 1 to
select gate time range of 0.26
–0.72 seconds.
3.
Adjust the vernier potentiometer to obtain a display of 1800
.
See label on back of SPD-100, SPD-100L for additional
information
1. Calculating Signal Frequency (in Hz)
Multiply RPM times the number of teeth (or discontinuities), then
divide by 60. For example, sensing a ring gear with 113 teeth
rotating at 1800 RPM gives a frequency of 3390 Hz.
Signal Frequency in Hz
=
(RPM) x (Teeth or Discontinuities)
60
Signal Frequency in Hz
=
((1800 RPM) x (113 Teeth)
= 3390 Hz
60
2. Calculating Gate Time (In seconds)
Divide the number to be displayed on the SPD -100 or SPD-
100L by the corresponding signal frequency.
Gate Time =
1800 RPM
= 0.53 seconds
3390 Hz
3. Gate Time Range Selection on 4-Position Switch
Select either position for each number pair on the switch:
z
Position 1: 0.26
–0.72 sec. Position 2: 0.72–1.43sec.
Position 3: 1.43
–2.85 sec. Position 4: 2.85–5.70sec.
Optional Calibration Method: On-engine
A.
Select the appropriate gate time range on the 4-position
switch.
B.
Connect the magnetic pickup output to terminals 1 & 2.
C.
Adjust vernier potentiometer on SPD-100 or SPD-100L
until its display agrees with another precise digital
tachometer.
OUTLINE AND CONNECTION DRAWING
SPD-100, SPD-100L, F-15, and F-16 are trademarks of Dynalco Controls.
DYNALCO RESERVES THE RIGHT TO CHANGE THESE SPECIFICATIONS WITHOUT
NOTICE
Barksdale Inc.
Barksdale and Dynalco Products
3211 Fruitland Ave
Los Angeles, CA 90058
