Polaroid Sun 660

Hi,
Just hacked a Polaroid Sun 660. Hooked it up according to Dennis Clark's schematic. Transducer is clicking, but readings are erratic.
Also, I am getting a low to high bump on Echo, even when the transducer is disconnected. Is this normal?
Thanks, John
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snipped-for-privacy@byrley-law.com wrote:

Assuming the connections are good and the circuit is not faulty (was the camera damaged before or during your deconstruction?) I'd look at your current from the power source. The ultrasonic transducer in these Polaroids pull over one amp when firing. Be sure your power supply can provide that. If it's through a small regulator the regulator might be folding back momentarily from the excessive current draw.
-- Gordon
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Thanks Gordon.
The power source is straight from a four-pack of fresh AA batteries, not a regulator.
This same issue is also occurring with another 660 board I got out of a different camera, so I would assume it's not the board's fault.
So, just to be clear, is it true that the ECHO line should _not_ be registering any kind of voltage bump if the transducer is disconnected? I.e., if the transducer is disconnected while the board cycles through "power up, pause, init, pause, power down, pause" routine, ECHO should be flat line, right? Or no?
BTW, your book (quite tattered now) was what got me into hobby robotics several years ago, so I owe you a debt of gratitude.
John
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Hmmm... It's been too long ago since I hacked my 660 (5-6 years now) that I don't remember the behavior of the echo line, but I'd be surprised if there wasn't a signal on ALL the lines during a pulse, and probably at other times too. We're talking a board made for a couple dollars (forget how much they charge for a new one now), so I don't think it has real tight design paramaters.
Is there a need to even care what the ECHO line does, except for the short period after the blanking period, and the max 60 feet for send and return times? IOW, will it matter that the echo line is noisy at times other than after firing a pulse?
I wonder what happens when you fire the board without a transducer? Will this harm the output stage of the board, the way an output transistor can be blown on an amp if there's no load (speaker) attached to it? Am I right in remembering that these transducers appear as both a capacitor and an inductor to the board? Can't remember where I read that. Maybe there's something on the net that shows how to simulate the load of the transducer if you want to do testing without a transducer attached.
Thanks for the comment about the book. Its main purpose has always been to inspire. That's 90% of this hobby/business anyway. From your e-mail address, I thought at first you were talking about my WordPerfect macros book. That's the one most law-related folks know me by.
-- Gordon
snipped-for-privacy@byrley-law.com wrote:

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http://www.senscomp.com/specsheets.htm http://www.senscomp.com/specs/600%20instrument%20spec.pdf -transducer
http://www.senscomp.com/specs/6500%20module%20spec.pdf - ranging module. Essentially the same beast just surface mount (not the extended version).
http://www.senscomp.com/techpapers.htm - in particular inputs and outputs for normal operation.
Also check out the chips TL851,TL852. These are the same as on the 660 ranger though they may have SN28xxx numbers and be in dip form. You could always hunt down the same chips on the Texas Instruments site for the original datasheet of the dip version.
have fun damnit.

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