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It seems there is an amplifier in BBS coils. How is it powered?
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In the Sovereign, yes. Not sure about later models. It was powered by a pick-up coil placed inside the TX coil, which formed a transformer. -
Ahhh- wireless power! I wouldn't have thought of that.
What is used for amplification - or is it more just a buffer?
My interest is DIY coils for the excal II.Comment
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on archive DVD a way to files conc the coil preamp - \Minelab\Sovereign GT & Elite\Sovereign coilComment
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Huh? What archive CD?Comment
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See this thread for the Sov preamp schematic:
http://www.geotech1.com/forums/showt...vereign+preamp
Here is a pic of the coil:
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Guys are hooking up a dc meter to the coil output, set at dc, and getting an ID meter out of it. How does that work if there is just an amp after the rx coil?Comment
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Only thing that would measure is target intensity. Nothing to do with target type I would think.Comment
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The Sovereign outputs a DC voltage from a DAC inside the box and the level indicates target ID. The voltage is on pin 5 of the chassis connector. Nothing to do with the coil. The meters were powered by rectifying the 10V Tx signal same as the coil pre-amp. Not sure if the Excalibur has a DAC or not?Originally posted by bklein View PostComment
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I was always curious how that worked, but not enough to go look myself. Thanks!Originally posted by Altra View PostComment
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Yeah! I've been reading through Excal/Beach forum threads and this just didn't make sense. Now it does. I don't think the Excal has the DAC output - it does have unused solder connections on the board but no-one's ever said what these are for.Comment
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I believe the Excalibur does in fact have a DAC. On the Sovereign the DAC feeds a VCO that generates the audio ID tones. The Excalibur has the same tone system. I have a junk Excalibur some where, I'll dig it out and verify.Comment
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While you are at it if you have any insight regarding the open wire connects on the pcb edge I'd be interested in understanding. Maybe some are common - I haven't looked in detail yet.Comment
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It does have a Maxim MX7541 DAC. Unfortunately that part is sandwiched in the center pcb, which makes it hard to see the traces and parts. Some where on the net I remember someone posted photos of the pcb's unsoldered. Maybe Findmall? Post a photo of the unsoldered connections you mentioned.
Add: found the photos
http://www.findmall.com/read.php?21,...782897,quote=1
https://datasheets.maximintegrated.c...ds/MX7541A.pdfComment
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