Hitting the High Notes
An ultrasonic distance meter & liquid-level gauge
Published in issue 346, September 2005
Lengths and distances are usually measured using a yardstick or measuring tape. For inaccessible locations, and especially for measuring the level of a liquid in a container, using an ultrasonic device to measure distance is an attractive alternative.
Power supply board
Resistor:
R1 = 33k
Capacitors*:
C1,C2,C6,C8,C9 = 220µF 25V radial
C3,C5,C7,C10 = 100µF 25V radial
C4 = 470µF 16V radial
C11 = 10nF
Semiconductors:
B1 = bridge rectifier 80V (or 40V), 0.8 A
D1-D4 = 1N4001
IC1 = 7815
IC2 = 7805
IC3 = 7905
IC4 = 7915
Miscellaneous:
K1 = 5-way SIL header
K2 = 2-way PCB terminal block, lead pitch 7.5mm
Tr1 = mains transformer 2 x 6V @ 2 x 233mA (e.g., ERA BV030-7590.0U)
F1 = fuse, 63mAT (time lag), with PCB mount holder (lead pitch 22.5mm) (not required if a short-circuit resistant transformer is used)
Main circuit board
Resistors:
R1,R3 = 3k
R2 = 68k
R4 = 110k
R5 = 16k
R6 = 3k3
R7 = 56k
R8 = 10k
R9 = 270, 1%
R10 = 750, 1%
R11 = 33
R12 = 22k
R13,R16,R18 = 120k
R14,R17 = 180k
R15,R19,R20 = 82k
R21 = 47k
R22 = 1k5
R23,R24,R25 = 5k6
R26-R33 = 270
P1 = 10k preset, H
Capacitors*:
C1,C3 = 2nF2
C2 = 27pF
C4 = 15pF
C5 = 1µF, lead pitch 5mm or 7.5mm
C6 = 33nF
C7 = 10nF
C8,C11,C12,C14, C15,C16,C17 = 100nF
C9,C10 = 22pF
C13 = 220nF, lead pitch 5mm or 7.5mm
Semiconductors:
D1 = 1N4148
T1,T2,T3 = BC557A
IC1,IC4 = TL082P
IC2 = ATmega8-16PC, programmed, order code 040015-41
IC3 = LM833N
Miscellaneous:
X1 = 8MHz quartz crystal
K1 = 5-way pinheader and mating socket
K2 = 6-way pinheader (2x3 block)
K3 = 3-way pinheader, straight
K4 = 16-way pinheader, straight
K5 = 14-way (2x7) pinheader, straight
K6 = 9-way D subminiature socket (female)
Solder pins
1 off 28-way IC socket, narrow-DIL
3 off 8-way IC socket
S1 = pushbutton, 1 make contact
LCD module with 44780 controller; 2x16 characters (optionally: with backlight; Display Tech 162)
ABS case, min. inside dimensions 125 x 102mm (splashproof; approved for damp room / outdoor use)
Display board
LD1,LD2,LD3 = 7-segment display, common anode, 20mm high (Kingbright SA08-11 SRWA)
K1 = 14-way (2x7) pinheader
Sensor head
R1 = NTC, 10k
R2 = 12k, 1%
UT1 = ultrasonic emitter (36-40 kHz)
UR1 = ultrasonic receiver (36-40 kHz)
5-way cable with individual screening (e.g., microphone cable); see text
Splashproof ABS case with strain relief grommet and locking nut (Bopla ET205, BF7, GM7)
*All capacitors 5mm lead pitch unless otherwise indicated
Ultrasonic transmitter and receiver
Suggested sources and order numbers:
maplin
HY12N (receiver/transmitter pair)
conrad
400ST160/MA40-S 182273-12
400ST160/MA40-R 182281-12
reichelt
400ST160/UST-40T UST-40T
400SR160/UST-40R UST-40R
segor
UST-40 T UST-40 T
UST-40 R UST-40 R
simons-elektronik
UST-40T UST-40T
UST-40R UST-40R
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Click below to download a PDF copy of this article from Elektor magazine. Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
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