Dynalco LST-108L User Manual

LST-108 and LST-108L

SELF-POWERED TACHOMETER

Calibration Instructions

The LST-108 and LST-108L tachometers are normally factory­calibrated to the customer-specified number of sensing teeth or

discontinuities, sensing speed, and desired numerical display.

If necessary, turn to the reverse side of the card to
calculate Signal Frequency and Gate Time.

To calibrate an LST-108 or LST -108L:

1. Remove the sealing plug on the back of the housing.

2. Apply the calculated signal frequency to terminals A and B.

A Dynalco F-16 or F-15 signal generator is ideal.

3. Select the appropriate gate time range on the 4-position
switch.

side of card.

4. Adjust the vernier potentiometer for the desired display.

See below

See label on back of LST-108; LST-108L; or Item 3, reverse

.

Shown with sealing plug removed

Vernier potentiometer

[clockwise to increase display reading;
counterclockwise to decrease]

4-position switch

Example:

1.Apply 3390 Hz to terminals A and B on tachometer (no polarity).

2.Turn the gate time range switch to (either) position number 2 to

select gate time range of 0.38 – 0.76 seconds.

3.Adjust the vernier potentiometer to obtain a display of 1800.

See label on back of LST-108, LST-108L for additional information

GATE TIME

CALCULATION

If 3390 Hz = 1800 RPM, then gate time is 0.53 seconds.

QUICK

}

(For example: 60 / 113 teeth = 0.53 sec. gate time)

60

Number of

Teeth

Assumes the pickup is “seeing” the
gear of interest directly, not through

{

a step up or step down ratio

.

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 1 13 teeth rotating
at 1800 RPM gives a frequency of 3390 Hz.

Signal Frequency in Hz =

Signal Frequency in Hz = = 3390 Hz

(RPM) x (Teeth or Discontinuities)
60

(1800 RPM) x (113 Teeth)
60

2. Calculating Gate Time (In seconds)

Divide the number to be displayed on the LST-108 or LST-108L
by the corresponding signal frequency.

Gate Time = = 0.53 seconds

.

1800 RPM
3390 Hz

3. Gate Time Range Selection on 4-Position Switch

Select either position for each number pair on the switch:

Position 1: 0.14– 0.38 sec. Position 2: 0.38–0.76 sec.
Position 3: 0.76– 1.51 sec. Position 4: 1.51–3.02 sec.

4. Pulse Rate Multiplier: Required gate time can be divided by

ten if a jumper from 4 to 5 is used. The input pulse rate will
be multiplied by ten times. Required gate time can be
divided by one hundred if a jumper from 5 to 6 is used. The
input pulse rate will be multiplied by one hundred times.

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 A & B.
C. Adjust vernier potentiometer on LST-108 or LST-108L until its

display agrees with another precise digital tachometer.

OUTLINE AND CONNECTION DRAWING

DYNALCO CONTROLS RESERVES THE RIGHT TO CHANGE THESE SPECIFICATIONS WITHOUT NOTICE.

Dynalco Controls, 3690 N.W. 53rd Street, Ft. Lauderdale, FL USA 33309

© 1996

LST-108 and LST-108L are trademarks of Dynalco Controls

TEL: [phone] FAX: [phone]

0396F