8 9

11

8 9

5

10

3

4

212

1

R410K

R14K7

R24K7

C122n

R322K

C210n

VR1100K C3

2u2

R6470

R5470

D2

IC1LM2917

D1

SW1sensor

2

C210n

8

3

1

4

7

5

6

IC1

R1100KC1

1u

15v

0v

FreqInput

VR147K

Over Frequency Indicator with flashing LEDTrip point >100Hz.

R2430

R368

R4150

8 9

2

C210n

8

3

1

4

7

5

6

IC1

R1100KC1

1u

15v

0v

FreqInput

Frequency switchPin 5 low when Fin> 1/(2 R1 x C2)In this example, switch frequency = 500Hz

R34K7

R44K7

R21K

Tachometer driven from points (sensor). Modification has beemade to enable the source to be pulsed DC instead of AC.Note this uses the 14pin version of the IC.

LM2917 EXAMPLE CIRCUITS

The following examples have been taken from the PDF datasheet.

There are 2 types: Frequency to voltage conversion Frequency detection

8 9

2

C222n

8

3

1 4

7

5 6

IC1LM

2917N-8

R1100K

R210K

C11u

12v

0v

Vout66Hz/V

ACInput

R3470

Basic Frequency to Voltage Converter.Will measure from around 10Hz to 700Hz.Input must be an AC signal.

D3

Frequency to Voltage conversion

Frequency Detection