marken@aero.UUCP (03/11/87)
I would appreciate information regarding use of the Polaroid camera's ultrasonic sensor as a digital yardstick. I recall reading an article on how to build such a device -- the article appeared about 3 years ago in Byte or Radio Electronics. Does anyone recall seeing such an article or have some recommendations regarding where a schematic could be obtained? Thanks. Rick Marken Aerospace Corp. ARPA: marken@aero UUCP:(decvax,ucbvax)!trwrb!aero!marken
mcintyre@rpics.UUCP (03/12/87)
In article <8455@aero.ARPA>, marken@aero.ARPA (Richard Marken) writes: > I would appreciate information regarding use of the Polaroid camera's > ultrasonic sensor as a digital yardstick. I recall reading an article > on how to build such a device -- the article appeared about 3 years ago > in Byte or Radio Electronics. Does anyone recall seeing such an article or > have some recommendations regarding where a schematic could be obtained? I built this kit and used in on top of a modified Milton Bradley Big Trak as a simple project in turtle building. The schematic was in Steve Ciarcia's "Circuit Cellar" about a year or so ago. It would be in Byte's index, and maybe in one of the later volumes of Steve's Circuit Cellar compilation books. I bought the actual kit from Micromint, the company that supplies parts and kits for a lot of the cellar projects. They advertise every month in Byte. By the way....it worked!!! It was pretty darn neat!! -- Dave "mr question " McIntyre seismo!rpics!mcintyre mcintyre@csv.rpi.edu
dennisg@fritz.UUCP (03/13/87)
In article <8455@aero.ARPA> marken@aero.UUCP (Richard Marken) writes: >I would appreciate information regarding use of the Polaroid camera's >ultrasonic sensor as a digital yardstick. I recall reading an article >on how to build such a device -- the article appeared about 3 years ago >in Byte or Radio Electronics. Does anyone recall seeing such an article or >have some recommendations regarding where a schematic could be obtained? There was such an article in the "Circuit Cellar" column of Byte. Three years ago sounds about right. A couple of years before that, the same column added a Polaroid ultrasonic rangefinder to a light sensor and parabolic mirror arrangement mounted on a stepping motor. That one was probably entitled "I've Got You In My Scanner". I have the issues at home, in a pile awaiting construction of a homebrew unit of similar ilk. I would discourage use of the Polaroid unit in hacker applications because it is quite expensive. A cheaper alternative is the LM1812 chip. Data is available in National Semi's analog databook. I'll post more info tomorrow.
commgrp@silver.UUCP (03/13/87)
The Polaroid Ultrasonic Ranging System is a sophisticated device; it emits a successive burst of multiple ultrasonic frequencies (similar to the swept-frequency chirps of bats) in order to eliminate flase readings caused by resonances. Receiver gain is increased in a series of timed steps after each pulse is transmitted, to reduce false readings caused by echoes from nearby objects not in the main beam (surprisingly narrow; -3 dB width about 8 degrees). The unit is supplied with excellent documentation. (I'll Xerox schematic for SASE.) I bought one several years ago, to use for measuring ceiling heights, etc., in cave-mapping. I installed it in an old Civil Defense geiger counter case. The shell of a military-type connector, with screw-on cap, protects the transducer when not in use. I mounted a flashlight reflector/bulb assembly in the meter-hole of the case, and connected it to a pair of D-cells; the light is essential for aiming the narrow beam. The rangefinder itself uses a 6-volt flat Polaroid "letter bomb" battery. The unit's digital readout indicates feet and tenths of a foot, to a maximum range of 30.4 feet. I have not tried to extend the range. One problem with the rangefinder, probably not significant to most people, is that it's incompatible with bats! Its pulses seem to disturb them severely, and when used in the presence of bats (I don't know the species), it gives random readings. There's an ad for the Polaroid ultrasonic rangefinder in SENSORS magazine, March 1987, p. 27. Polaroid Corp Ultrasonic Components Group 119 Windsor Street Cambridge, MA 02139 ph: (617) 577-4681 The Polaroid Ultrasonic Ranging System Designer's Kit cost $165 (too much in my opinion, but they've got a captive audience). Frank Reid PO Box 5283 Bloomington IN 47402 reid@gold.bacs.indiana.edu
dennisg@fritz.UUCP (03/14/87)
Here's the bibliography of ultrasonic detection/ranging projects that I promised yesterday. I would appreciate seeing other references. o "An Ultrasonic Ranging System, Build the SonarTape" by Steve Ciarcia Byte, October 1984, pg 113 Notes: Uses Polaroid transducer and TI control module (combo costs about $60). Interfaced to LSI display driver and LCD display. o "Home In on the Range! An Ultrasonic Ranging System" by Steve Ciarcia Byte, November 1980, pg 32 Notes: Uses Polaroid Ultrasonic Ranging System Designer's kit ($125). Interfaced to computer via parallel port (BCD). Internal details of the ranging module are presented. The ranging transducer is mounted on a computer-controlled stepper motor assembly. See Byte, November 1978, page 76. o "Ask Byte" by Steve Ciarcia Byte, November 1980, pg 266 Notes: Uses individual ultrasonic transmitter and receiver circuits. Two transmitters are provided: one just a 555, and the other a 555 driving a LM1812. The receiver is an NE567 phase-locked loop. o "Ask Byte" by Steve Ciarcia Byte, June 1982, pg 266 Notes: Same circuits as Byte, November 1980, pg 266. o "Sonic Motion Detector" by David Benzel Radio Electronics, September 1984, page 51 Notes: Detects motion by doppler shift of continously operating transmitter. Receiver requires numerous OP-amps, and discrete components. o "The Electronic Scientist" by Forrest Mims Computers and Electronics, June 1983, page 84 Notes: Uses Polaroid Ultrasonic Ranging System Designer's kit ($150). Few details about the internals of the rangefinder module are presented. Author adds an audible output that makes low-pitched thumps for nearby objects and high-pitched chirps for distant ones. o "LM1812 Data Sheet" National Semiconductor Linear Databook, 1982, page 9-77 Notes: A one-chip solution for many ultrasonic detection and ranging needs. Provides schematic of an ultrasonic ranging system that spans 4 inches to 6 feet in air: one chip, two coils, three resistors, 8 capacitors, and a transducer. Adding a 555 and some minor components yields a range of 3 feet to 20 feet. The coils used appear to be strange, and perhaps hard to find. Also included is schematic of 200 kHz depth sounder spanning 5 feet to 100 feet in water. o "AB-20 Application Brief" National Semiconductor Linear Applications Databook, 1986, page 1083 by Mitchell Lee Notes: Provides schematic of an ultrasonic ranging system that spans 4 inches to 30 feet: one chip, two coils, four resistors, 8 capacitors, 2 transistors, three diodes, and a Polaroid transducer. One coil has a strange part number, but specs are provided. The other is a transformer that you wind yourself from standard parts. Also included is some juicy technical information, like a note that piezoelectric transducers "ring" for as long as 20 msec (masking up to 10 feet of range)! o "Judging Distance" "Microprocessor Based Robotics", page 95 by Mark Robillard Notes: Provides several simple ultrasonic circuits: 555-based transmitter, NE567-based receiver (741 or discrete pre-amp). Also shows a ranging circuit based on the LM1812: one chip, two coils, five fixed resistors, two pots, 8 capacitors, and a transducer. Adding a 555 and some minor components increases the range. The coils used are standard "Miller" parts, and should be fairly easy to find.
commgrp@silver.UUCP (03/14/87)
Re: Ultrasonic Rangefinders Simple sonic/ultrasonic rangefinder-- Requires two units, transmitter and receiver: Transmitter simultaneously emits flash of light and pulse of sound. Reciever starts timer when it detects light, stops timer when sound arrives. Time is proportional to distance between transmitter and receiver. Since the first sound to reach the receiver will be that which has travelled in a straight line between them, there will be no problem with echoes. Sound travels ~1100 feet per second, or about an inch in 1/10 ms. The wavelength of sound should be a fraction of the unit's resolution; about 40 kHz should be suitable for a unit which indicates the nearest inch. -- from "How to make an ultrasonic rangefinder" by Bill Mixon, reprinted in SPELEONICS 4 (v.1 no.4 winter-spring 1985-86) --- Frank Reid reid@gold.bacs.indiana.edu
eacj@batcomputer.tn.cornell.edu (Julian Vrieslander) (03/19/87)
Scanning my junk mail tonight, I found an advertisement for a product called
"Sonic Tape." Apparently, it is an ultrasonic rangefinder. It is battery
operated, about the size of a large Walkman, and alleged to be accurate to
within one inch over distances up to 180 feet. Readout is via a numeric LED
display. The manufacturer is a company called Cynex, but I have no address.
The advertisement appeared in a catalog from Sync, Inc. (phone: 800-621-5800).
Price is $250 (whew!).
Obvious disclaimer: I have no idea whether this thing is legit or a toy.
--
Julian Vrieslander, Neurobiology & Behavior, Cornell Univ., Ithaca, NY 14853
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