Comments on: Ultrasonic Rangefinder, Part III: Receiver / LogoChip Interface Attempt http://www.neufeld.newton.ks.us/electronics/?p=42 Sun, 08 Dec 2024 17:19:24 -0600 hourly 1 http://wordpress.org/?v=3.1.3 By: Keith Neufeld http://www.neufeld.newton.ks.us/electronics/?p=42&cpage=1#comment-22696 Keith Neufeld Thu, 08 Jan 2009 19:28:41 +0000 http://www.neufeld.newton.ks.us/electronics/?p=42#comment-22696 Jon, I have to confess that I haven't touched this project in a long time, and had to reread my own entries to catch myself up to date. I really don't remember exactly what modifications I made to the original. One thing I do remember is discovering to my embarrassment that Gerald Coe's schematic on which I based my design was in fact the schematic for one of the wildly successful <a href="http://www.robot-electronics.co.uk/acatalog/Ultrasonic_Rangers.html" rel="nofollow">SRF series of ultrasonic rangefinders</a>, the very ones I described as too expensive and was trying to supplant. At this point, I would actually encourage you to look into his sensors, <a href="http://www.acroname.com/robotics/parts/R93-SRF04.html" rel="nofollow">available from Acroname</a>. I've used them and they're very robust, reliable, and easy to interface. That said and regardless of which way you choose to go, I can't imagine that 1' leads will be a problem at 24kHz. I don't think the placement of the 1nF capacitor matters -- it's just capacitive coupling for the op-amp section, to block DC and begin to high-pass filter the input. I don't see any reason you couldn't use relays to multiplex your sensors, although I don't think I'd choose to do it that way myself. Relay-related problems aren't insurmountable, but you'll want to be careful to put a back-EMF protection diode across the coil; and you won't be able to change sensors as rapidly because you'll have to allow time for the relay contacts to settle; and for a mobile robot, if I were doing it, I'd find which way the relay's lever moves and lay the relay on its side so that jostling over rough terrain doesn't make and break contact when not desired by the controller. Best of luck with your project; and if you have a blog or a site for it, I'd love to you have you post another comment linking to it! Jon, I have to confess that I haven’t touched this project in a long time, and had to reread my own entries to catch myself up to date. I really don’t remember exactly what modifications I made to the original.

One thing I do remember is discovering to my embarrassment that Gerald Coe’s schematic on which I based my design was in fact the schematic for one of the wildly successful SRF series of ultrasonic rangefinders, the very ones I described as too expensive and was trying to supplant. At this point, I would actually encourage you to look into his sensors, available from Acroname. I’ve used them and they’re very robust, reliable, and easy to interface.

That said and regardless of which way you choose to go, I can’t imagine that 1′ leads will be a problem at 24kHz. I don’t think the placement of the 1nF capacitor matters — it’s just capacitive coupling for the op-amp section, to block DC and begin to high-pass filter the input.

I don’t see any reason you couldn’t use relays to multiplex your sensors, although I don’t think I’d choose to do it that way myself. Relay-related problems aren’t insurmountable, but you’ll want to be careful to put a back-EMF protection diode across the coil; and you won’t be able to change sensors as rapidly because you’ll have to allow time for the relay contacts to settle; and for a mobile robot, if I were doing it, I’d find which way the relay’s lever moves and lay the relay on its side so that jostling over rough terrain doesn’t make and break contact when not desired by the controller.

Best of luck with your project; and if you have a blog or a site for it, I’d love to you have you post another comment linking to it!

]]> By: Jon http://www.neufeld.newton.ks.us/electronics/?p=42&cpage=1#comment-22693 Jon Thu, 08 Jan 2009 06:41:03 +0000 http://www.neufeld.newton.ks.us/electronics/?p=42#comment-22693 Hi Keith, I have really enjoyed reading your blog entries! However I have a few questions. I am currently working on a robot and am hoping to add some ultrasonic sensors. I have read all of your DIY Ultrasonic entries but was wondering if the only modification that you made to the original schematic was removing the 1M feedback resistors on the amplifiers. I was also wondering if you knew whether or not long leads (about 1ft) to the transducers would cause interface problems. Should the 1nf capacitor be very close to the transducer? If possible I would like to build the reciever/xmitter circuit only once and then use a set of relays to multiplex the circuit to multiple pairs of transducers. If not I will have a fun time soldering 8+ PCBs :) Any advice would be greatly appreciated and again I have to compliment you on having such a great, well-maintained site! Thanks! Jon Hi Keith,

I have really enjoyed reading your blog entries! However I have a few questions.

I am currently working on a robot and am hoping to add some ultrasonic sensors. I have read all of your DIY Ultrasonic entries but was wondering if the only modification that you made to the original schematic was removing the 1M feedback resistors on the amplifiers.

I was also wondering if you knew whether or not long leads (about 1ft) to the transducers would cause interface problems. Should the 1nf capacitor be very close to the transducer? If possible I would like to build the reciever/xmitter circuit only once and then use a set of relays to multiplex the circuit to multiple pairs of transducers. If not I will have a fun time soldering 8+ PCBs :)

Any advice would be greatly appreciated and again I have to compliment you on having such a great, well-maintained site!

Thanks!

Jon

]]> By: Joe Hoerl http://www.neufeld.newton.ks.us/electronics/?p=42&cpage=1#comment-22679 Joe Hoerl Fri, 02 Jan 2009 04:43:13 +0000 http://www.neufeld.newton.ks.us/electronics/?p=42#comment-22679 Horatiu, the Senscomp (formerly Polaroid) ultrasonic range finder has the best distance at around 10 meters. The problem with not waiting for the echo would be the synchronization of timing to understand the time the signal is sent vs. received. I'm not aware of any devices that work in this manner. Possibly there are some laser range finders which might suit your need and are commonly used in surveying and aligning of cranes, etc. Horatiu, the Senscomp (formerly Polaroid) ultrasonic range finder has the best distance at around 10 meters. The problem with not waiting for the echo would be the synchronization of timing to understand the time the signal is sent vs. received. I’m not aware of any devices that work in this manner. Possibly there are some laser range finders which might suit your need and are commonly used in surveying and aligning of cranes, etc.

]]> By: Keith Neufeld http://www.neufeld.newton.ks.us/electronics/?p=42&cpage=1#comment-22566 Keith Neufeld Sun, 30 Nov 2008 20:32:46 +0000 http://www.neufeld.newton.ks.us/electronics/?p=42#comment-22566 Horatiu, I understand now what you mean about separate transmitter and receiver, rather than a single transceiver. However, I'm still not familiar with the market and am not specifically aware of any components that would work for you. Horatiu, I understand now what you mean about separate transmitter and receiver, rather than a single transceiver. However, I’m still not familiar with the market and am not specifically aware of any components that would work for you.

]]> By: Horatiu Vornica http://www.neufeld.newton.ks.us/electronics/?p=42&cpage=1#comment-22563 Horatiu Vornica Sun, 30 Nov 2008 17:16:11 +0000 http://www.neufeld.newton.ks.us/electronics/?p=42#comment-22563 Actually the distance from the transmitter to the receiver is varying between 1 meter and 35 meters. The speed the transmitter is moving is 1m/s, which is the mobile platform speed; to this mobile platform I need to know the position. This platform has a vertical up and down movement, like an elevator. Actually the distance from the transmitter to the receiver is varying between 1 meter and 35 meters. The speed the transmitter is moving is 1m/s, which is the mobile platform speed; to this mobile platform I need to know the position. This platform has a vertical up and down movement, like an elevator.

]]> By: Horatiu Vornica http://www.neufeld.newton.ks.us/electronics/?p=42&cpage=1#comment-22562 Horatiu Vornica Sun, 30 Nov 2008 17:10:40 +0000 http://www.neufeld.newton.ks.us/electronics/?p=42#comment-22562 By "no need for echo sonar" I was trying to say: I don't need to transmit a signal and wait for the reflected signal to come back. I need to transmit a signal and in the other part to have the receiver who will receive the direct signal; The transmitter is mobile on one axis, so in this way I can measure the distance between the transmitter and the receiver; the distance between the transmitter and the receiver is 35 meters, but the signal is much stronger then is in the "echo sonar" method. By “no need for echo sonar” I was trying to say: I don’t need to transmit a signal and wait for the reflected signal to come back. I need to transmit a signal and in the other part to have the receiver who will receive the direct signal; The transmitter is mobile on one axis, so in this way I can measure the distance between the transmitter and the receiver; the distance between the transmitter and the receiver is 35 meters, but the signal is much stronger then is in the “echo sonar” method.

]]> By: Keith Neufeld http://www.neufeld.newton.ks.us/electronics/?p=42&cpage=1#comment-22557 Keith Neufeld Sat, 29 Nov 2008 16:21:45 +0000 http://www.neufeld.newton.ks.us/electronics/?p=42#comment-22557 Horatiu, I'm not sure what you mean by "no need for echo sonar," unless you mean that the ultrasonic rangefinder doesn't need to rotate. I'm not aware of any with a range of 35m -- the ones I've used max out at about 5m. I would guess you might be able to find some from industrial automation suppliers, but I don't have anything specific in mind. Horatiu, I’m not sure what you mean by “no need for echo sonar,” unless you mean that the ultrasonic rangefinder doesn’t need to rotate.

I’m not aware of any with a range of 35m — the ones I’ve used max out at about 5m. I would guess you might be able to find some from industrial automation suppliers, but I don’t have anything specific in mind.

]]> By: Horatiu Vornica http://www.neufeld.newton.ks.us/electronics/?p=42&cpage=1#comment-22541 Horatiu Vornica Tue, 25 Nov 2008 17:18:17 +0000 http://www.neufeld.newton.ks.us/electronics/?p=42#comment-22541 I need to use a "simple" ultrasonic positioning; there is no need for echo sonar. I only need a ultrasonic burst from a mobile transmitter and at maximum 35 meters a receiver; "one way" positioning for an elevating platform. The same controller board will give the transmit signal(though a flexible cable) and receive the signal. Could you recommend some websites or some technical documentation about this? I need to use a “simple” ultrasonic positioning; there is no need for echo sonar. I only need a ultrasonic burst from a mobile transmitter and at maximum 35 meters a receiver; “one way” positioning for an elevating platform. The same controller board will give the transmit signal(though a flexible cable) and receive the signal.
Could you recommend some websites or some technical documentation about this?

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