Under Speed Warning Alarm for Magnetic Pickup sensor – Frequency Controlled Switch

  • Rajkumar Sharma
  • 73 Views
  • easy
  • Tested
  • SKU: EL118258
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This is an under-speed sensor module that provides an audible warning and signals output when the speed of a machine is below the set point. The module can be used in applications such as Engines, Machines, Sports machines, Fitness Equipment, Speed of the machine or engine can be detected using a magnetic pickup sensor. The project can be used in many applications where an under-speed monitor is important. The project is based on the LM2907 chip which works as a frequency to voltage converter, interfacing magnetic pickup as shown in the figure below. A typical magnetic pickup for automotive applications will provide a thousand pulses per mile so that at 60 mph the incoming frequency will be ~16.6 Hz. If the reference level on the comparator is set by two equal resistors R2 and R6 then the desired value of C5 and R4 can be determined from the simple relationship:

The buzzer is activated when Frequency ≥ (1/(2XR4C5))

From the RC selection chart, we can choose the suitable values for R5 and C5. In the current circuit, the frequency is set to 500Hz approx. A frequency trigger point can be changed as per user requirement using the above equation. The module supports any sensor with voltage levels 20mV to 28V.

RC selection chart

Magnetic Pickup

A magnetic pickup consists of a permanent magnet, a pole-piece, and a sensing coil all encapsulated in a cylindrical case. A magnetic pickup is most frequently used to sense passing teeth on a gear, sprocket, or timing belt wheel, to bolt-heads, key-ways, or other moving machine-mounted targets.

If you are looking for “Over Speed Sensor – Over Speed Alarm using Magnetic Pickup Sensor” check the link attached.

Features

  • Supply 12 to 15V DC @ 20mA
  • Optimized for Magnetic Pickup Sensor
  • Other Optical Sensors, Mechanical sensors, Tachometer sensors can be used
  • Inputs Voltage Level 20mV to 28V
  • Buzzer Operates when the Input frequency is below 500Hz
  • Provide Low Output When Speed is below Setpoint
  • Header Connector for Supply Input and Output
  • 2 Pin Header for Sensor
  • D1 Power LED
  • PCB Dimensions 38.42 x 16.19 mm

Applications

  • Engines
  • Tachometer Under/Over Speed
  • Fitness Equipment
  • Sports Machines
  • Machine Automation
  • AC/DC Motor Speed Monitor

Schematic

Parts List

NOQNTYREF.DESCMANUFACTURERSUPPLIERPART NO
11BZ1BUZZER 5V SMD SIZE 12MMCUI DEVICESDIGIKEY102-CMI-1295-1285T-ND
21CN16 PIN MALE HEADER PITCH 2.54MMWURTHDIGIKEY732-5319-ND
31CN22 PIN MALE HEADER PITCH 2.54MMWURTHDIGIKEY732-5315-ND
41C31uF/25V SMD SIZE 1206MURATA/YAGEODIGIKEY
51C20.1uF/50V SMD SIZE 0805MURATA/YAGEODIGIKEY
61C4DNP
71C50.01uF/50V SMD SIZE 0805MURATA/YAGEODIGIKEY
81D1LED SMD SIZE 0805LITE ON INCDIGIKEY160-1427-1-ND
91Q1BC847ALMICRO COMMERCIALDIGIKEYBC847B-TPCT-ND
102R1,R71K 5% SMD SIZE 0805MURATA/YAGEODIGIKEY
113R2,R5,R65K1 1% SMD SIZE 0805MURATA/YAGEODIGIKEY
121R3100E 5% SMD SIZE 0805MURATA/YAGEODIGIKEY
131R4100K 1% SMD SIZE 0805MURATA/YAGEODIGIKEY
141U1LM2907-NTIDIGIKEYLM2907M-8/NOPB-ND
151C110uF/25V SMD SIZE 1206MURATA/YAGEODIGIKEY

Connections

Magnetic Pickup Sensor



Gerber View

Photos

Video


LM2907 Datasheet

lm2917-n

PCB

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