The equations governing the Duty Cycle and frequency of this configuration are

# The equations governing the duty cycle and frequency

This preview shows page 11 - 14 out of 15 pages.

cycle so that the operating frequency of the signal is maintained. The equations governing the Duty Cycle and frequency of this configuration are given as: 1 1 * * 67 . 0 ) ( C R HIGH t A 1 2 * * 67 . 0 ) ( C R LOW t B 2 1 t t T Period T f Frequency 1 where R A is equal to the total resistance of R 2 plus the resistance between R 2 and the tap of the potentiometer (between 1k and 11k ohms), and R B is equal to the resistance between the tap and R1 plus the resistance of R1 (between 1k and 11k ohms). The duty cycle varies from approximately 8% to 92%. Figure 18. Timing Diagram for the astable multivibrator Ask the TA to check your circuit. Show the output of your Astable multivibrator in an oscilloscope.
ECE 456/556 Mechatronics Signal Conditioning Lab Question Task TA Timed Exercise Page 12/15 Task 5: Designing your own ultrasonic sensor – Part 2 Figure 19. SRF04 Ultrasonic sensor connected to NE555 Trigger Circuit After getting the astable multivibrator circuit verified by the TA, connect the SRF04 ultrasonic sensor to the trigger circuit as shown in Figure 19. Connect the output of the ultrasonic sensor to the oscilloscope and hit the autoset button. Using the color sheet as an obstacle and place it in front of the ultrasonic sensor and complete the following table. The mean voltage of the signal can be measured from the oscilloscope. Distance (cm) Mean Voltage Reading 0 1 2 5 10 15 Task 6: Interfacing the Ultrasonic with EV3 To be able to succesfully interface the ultrasonic sensor that you built with the EV3, you need to trick the EV3 into thinking that it is connected to a touch sensor. The circuit in Figure 20 needs to be built to connect the ultrasonic sensor to the EV3. The port in the figure refers to the cable that is going to be connected to the EV3.
ECE 456/556 Mechatronics Signal Conditioning Lab Question Task TA Timed Exercise Page 13/15

#### You've reached the end of your free preview.

Want to read all 15 pages?

• Spring '08
• Chow
• RC circuit, Low-pass filter, Mechatronics Signal Conditioning, Mechatronics Signal Conditioning Lab, Signal Conditioning Lab