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depth finder transducer frequency question
On Tue, 13 Jan 2004 18:45:34 GMT, Gary Schafer
wrote: On Tue, 13 Jan 2004 10:39:15 -0600, "RB" wrote: No marks whatever. That's why I am trying to figure out some simple, practical way to figure out what the design freq is. Nothing comes to mind, though. If you have a variable audio generator, hook it to the transducer. Place an AC voltmeter across the transducer and slowly tune the audio generator around the the most common frequencies that the transducer could be. You should see a sudden rise in the voltage when you hit the frequency. Interesting, but how would you hook the unit across the transducer without taking it apart? Later, Tom S. Woodstock, CT ---------- "My rod and my reel - they comfort me." St. Pete, 12 Lb. Test |
#2
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depth finder transducer frequency question
}}} Interesting, but how would you hook the unit across the transducer
without taking it apart? {{{ If I understand the question, you would simply put the audio generator and ac voltmeter across the coax lead at some point (between the braid and the center). |
#3
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depth finder transducer frequency question
A lot of talk here of audio signal generators.
Although depth sounders are referred to as "sonar" they do not work at audio frequencies. Hi-Fi equipment can work up to 20K (salesmen and status-seekers will clain more) This is the upper level for people with good hearing. By the time we can afford boats and gadgets out hearing has deteriorated to much below this. Modern depth sounders work at 200K. This is radio frequency. Some years ago the most popular channel on BBC radio was on 200k. It would seem that, if you wish to test your fishfinder, you might be better off using a thirty year old European broadcast receiver and hold the antenna to the transducer. Henry |
#4
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depth finder transducer frequency question
On Tue, 13 Jan 2004 23:53:39 GMT, "Henry" wrote:
A lot of talk here of audio signal generators. Although depth sounders are referred to as "sonar" they do not work at audio frequencies. Hi-Fi equipment can work up to 20K (salesmen and status-seekers will clain more) This is the upper level for people with good hearing. By the time we can afford boats and gadgets out hearing has deteriorated to much below this. Modern depth sounders work at 200K. This is radio frequency. Some years ago the most popular channel on BBC radio was on 200k. It would seem that, if you wish to test your fishfinder, you might be better off using a thirty year old European broadcast receiver and hold the antenna to the transducer. Henry It depends on how you propagate it whether it is audio or RF. If you are transmitting audio you are transmitting an acoustic wave. If you are transmitting RF then you are transmitting an electromagnetic wave. You can have RF transmitted easily at 10 khz. You can also have audio at 10 khz, as an example. A depth sounder transmits audio. An acoustic wave. Although you could use an RF signal generator to test a transducer, if the signal generator went down that low. Most do not. While most better audio generators go up to about .5 mhz. Probably easier to find than an RF generator that covers that range. Yes RB, you have it correct as how to hook it up to the coax. 50 to 200 khz range will probably be where you find them. There are a few that go up to 400 khz. If I remember right 50 was common, 80, 120 or 125, 180, 200. 50 and 200 were the most popular. I may be wrong on some of the other frequencies. Maybe some more that I have forgotten too. Regards Gary |
#5
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depth finder transducer frequency question
It depends on how you propagate it whether it is audio or RF. If you are transmitting audio you are transmitting an acoustic wave. If you are transmitting RF then you are transmitting an electromagnetic wave. Thank you, this makes sense. I was trained in radio and perhaps was being too simplistic. Yes, I was not differentiating between acoustic pressure waves and EM waves. I should study the workings of the transducer. Can anyone help here? Does a transducer have a diaphragm vibrating at 200K? I must confess that my training started over 50 years ago (in the RAF). It was much simpler then (fishfinder, what's that?), and I now feel rather left behind. Henry |
#6
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depth finder transducer frequency question
On Wed, 14 Jan 2004 01:52:31 GMT, "Henry" wrote:
It depends on how you propagate it whether it is audio or RF. If you are transmitting audio you are transmitting an acoustic wave. If you are transmitting RF then you are transmitting an electromagnetic wave. Thank you, this makes sense. I was trained in radio and perhaps was being too simplistic. Yes, I was not differentiating between acoustic pressure waves and EM waves. I should study the workings of the transducer. Can anyone help here? Does a transducer have a diaphragm vibrating at 200K? Yes - actually, a piezoelectric crystal that vibrates at the operating frequency. -- Peter Bennett, VE7CEI peterbb (at) interchange.ubc.ca new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca |
#7
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depth finder transducer frequency question
In article .com,
Peter Bennett wrote: Yes - actually, a piezoelectric crystal that vibrates at the operating frequency. True, actually 90% of the piezoelectric crystal tranducers are Barium Titanate Crystals and most of these are made by one company. (I forget the name now, but they OEM to all the Sounder producers) The 28Khz Transducers are Magnetic Restriction types and not crystals, and the old WWII SubSignal "Big Whoppers" were also Magnetic Restriction types as well. It's really hard to get crystals to resonate below 50Khz with the power levels used by typical sounders below that frequency. Bruce in alaska -- add a 2 before @ |
#8
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depth finder transducer frequency question
The early Seafarer (Flashing neon) sounders in the UK ran at 150kHz.
"Gary Schafer" wrote in message ... On Tue, 13 Jan 2004 23:53:39 GMT, "Henry" wrote: A lot of talk here of audio signal generators. Although depth sounders are referred to as "sonar" they do not work at audio frequencies. Hi-Fi equipment can work up to 20K (salesmen and status-seekers will clain more) This is the upper level for people with good hearing. By the time we can afford boats and gadgets out hearing has deteriorated to much below this. Modern depth sounders work at 200K. This is radio frequency. Some years ago the most popular channel on BBC radio was on 200k. It would seem that, if you wish to test your fishfinder, you might be better off using a thirty year old European broadcast receiver and hold the antenna to the transducer. Henry It depends on how you propagate it whether it is audio or RF. If you are transmitting audio you are transmitting an acoustic wave. If you are transmitting RF then you are transmitting an electromagnetic wave. You can have RF transmitted easily at 10 khz. You can also have audio at 10 khz, as an example. A depth sounder transmits audio. An acoustic wave. Although you could use an RF signal generator to test a transducer, if the signal generator went down that low. Most do not. While most better audio generators go up to about .5 mhz. Probably easier to find than an RF generator that covers that range. Yes RB, you have it correct as how to hook it up to the coax. 50 to 200 khz range will probably be where you find them. There are a few that go up to 400 khz. If I remember right 50 was common, 80, 120 or 125, 180, 200. 50 and 200 were the most popular. I may be wrong on some of the other frequencies. Maybe some more that I have forgotten too. Regards Gary |
#9
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depth finder transducer frequency question
In article 7y%Mb.83359$X%5.9293@pd7tw2no, "Henry" wrote:
Modern depth sounders work at 200K. This is radio frequency. Well, maybe, but not for sure. Common sounder Frequencies a 50 Khz 88 Khz 100 Khz 200 Khz Most of the consumer type sounders are 200Khz, that is true, but there are a whole slew of different types and they use different frequencies, depending on the typical use. Bruce in alaska -- add a 2 before @ |
#10
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depth finder transducer frequency question
The most common US manufacturer is AirMar. It is common on modern
recreational type boats for dual frequency transducers running at 50 and/or 200 KHz to be installed. A lot of them also have Hall Effect speed sensors and a temperature sensor, hence are called dual frequency Tri-ducers. AirMar makes them as the OEM for Raymarine, Furuno, etc. If you have any numbers you can find on the cable, etc., I may be able to cross them to an AirMar equivalent and then give you the specifications and pin out. Doug K7ABX "Bruce in Alaska" wrote in message ... In article 7y%Mb.83359$X%5.9293@pd7tw2no, "Henry" wrote: Modern depth sounders work at 200K. This is radio frequency. Well, maybe, but not for sure. Common sounder Frequencies a 50 Khz 88 Khz 100 Khz 200 Khz Most of the consumer type sounders are 200Khz, that is true, but there are a whole slew of different types and they use different frequencies, depending on the typical use. Bruce in alaska -- add a 2 before @ |
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