# Free Electronic Circuits & 8085 projects

## The production of ultrasonic range finder (regular device)

Published on Mar 16 2011

Presented here do not use a foreign SCM ultrasonic range finder. The ultrasonic range finder, ultrasonic emission by measuring the time difference between the reflected back to the distance measurement and the measured object. Can measure the distance of 0.35-10m. Physical map as follows:

Schematic is as follows:

First, the circuit
An ultrasonic transmitter circuit
Formed by the two integrated circuits 555. IC1 (555) composed of ultrasonic pulse generator, the duty cycle is calculated as follows, the actual circuit components, such as error, there will be some differences.

Condition: RA = 9.1MΩ, RB = 150KΩ, C = 0.01μF
TL = 0.69 x RB x C
= 0.69 x 150 x 10 3 x 0.01 x 10 -6 = 1 msec

TH = 0.69 x (RA + RB) x C
= 0.69 x 9250 x 10 3 x 0.01 x 10 -6 = 64 msec

IC2 composition of ultrasonic carrier signal generator. Pulse signal output from the control of IC1, the output 1ms frequency 40kHz, 50% duty cycle pulse, stop 64ms. Calculated as follows:

Condition: RA = 1.5KΩ, RB = 15KΩ, C = 1000pF
TL = 0.69 x RB x C
= 0.69 x 15 x 10 3 x 1000 x 10 -12 = 10μsec

TH = 0.69 x (RA + RB) x C
= 0.69 x 16.5 x 10 3 x 1000 x 10 -12 = 11μsec

f = 1 / (TL + TH)
= 1 / ((10.35 + 11.39) x 10 -6 ) = 46.0 KHz
IC3 (CD4069) form the first ultrasonic transmitter driver circuit.