Page 110 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

Tuning the transmitter
Set up the ultrasonic transducers so that they are directly facing one
another about 4″ to 5″ apart (see Fig. 5.37). Connect the VOM to the
circuit as shown in the insert in Fig. 5.35. (Leave the comparator sec-
tion off.) Set the VOM to read volts DC. You will need to read about
2 V; set the range on the VOM accordingly. Turn on both circuits. Ad-
just R2 of the transmitter so that you obtain the peak voltage output
shown on the voltmeter. This should read about 2 VDC.
Adjusting the CMOS comparator
After tuning the transmitter, we need to set the receiver’s com-
parator circuit. Disconnect the VOM from the receiver section
and connect the CMOS comparator. Rearrange the transducers so
that they are lying side by side about half an inch apart facing in
the same direction. Place a flat-sided solid object about 3″ in front

Vcc

R3
1K R1 220
8 4
210222
7 3 89
4.7K 1K
R2 555
6 Ultrasonic
Transducer
2 1
.0047
F

Vcc = 5Volts

* Use CMOS 555 Timer
5.36 Ultrasonic transmitter circuit

Transmitter Voltmeter
Circuit Receiver
Circuit

4–5"
5.37 Ultrasonic test setup
Team LRN Sensors