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Cal 9.2 SilverSwan
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Discussion Starter #1 (Edited)
I'm in the process of trying to adapt the existing DMI speed sensor to a ST60 speed display. The DMI is a small signal magnetic reluctance unit and the Ray is a Hall effect with 0-12 volt signal.
I designed and ordered a PCB, removed components to simplify. Just need to install it on the boat and verify the calibration range on the ST60.
Has anyone tried to do this interface???
First attempt did not properly energise the transducer. Had to add a current source to allow the transducer to pull down when it trips. I took the DMI display apart and traced the circuit out to duplicate. I added a new input stage to the existing board, not a pretty site, but does work with the same sensitivity as the DMI unit. I like the DMI transducer with the wider paddle wheel blades, more sensitive at low hull speeds than the RM brand.
 

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Nope, I have done weird things but nothing like this :). But I think it shoud work, as these ST60 speed meters are just "pulse counters", and if you find a mean to bring your signel, that should suffice. Let us know the results ..... and good luck.
 

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Cal 9.2 SilverSwan
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302 Posts
Discussion Starter #3 (Edited)
Version #2 with DMI input energization stage. Not a pretty site but does work.
7-19-09 did a calibration check today against the Raystar GPS120. The cal mode allows for direct speed program using the SOG output from the 120. The St60 accepted the cal data and performed within .1 knots down to an idle.

Changed the ST60 top mounts to the flush mount bezels and installed them. I did a quick write up with a few photos. Just take the link:
DMI
 

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