Paddlewheel wiring

[biscuit]

I have replaced my old Stowe Navsounder and Navigator 1 displays with Echopilot Bronze Trio instruments, and very nice too. The existing Stowe depth transducer works very well with the new display, (Echopilots an be calibrated to suit a variety of inputs) but the speed/ log paddlewheel (84 mm long, 35mm diam. Red with s/s handle) doesn't seem to give any signal on the display. The magnet is intact and in place.
Echopilot supplied a paddlewheel transducer and housing, but its a lot shorter than the present housing, which is heavily glassed in. I am unwilling to start major surgery to fit this before exhausting other solutions. The cable is a single red wire inside a screen.
Are all paddle wheel logs wired like this? If so I wonder why it won't give any signal.
Perhaps I am wiring the thing wrongly, but its just a simple co-ax plug.
I have contacted the manufacturers, who can't seem to help. Advice please.

 

[pvb]

They don't all work the same way. I'd suggest you ask Stowe Marine Electronics for advice.

 

[SHUG]

Have you double checked that the Echopilot works with the paddlewhweel supplied with it.
As you seem to be aware, most paddle wheels have a magnet (or two) in the paddles which creates an electrical pulse as it passes by a coil in the head so two leads ,or signal and screen are needed from the head.
Thought........if the screen is earthed it might kill the signal. The screen and red wire should probably be "floating".

 

[biscuit]

Having re read the handbook, (which seems to be a little out of date now) I think I have a clearer notion of the appropriate connections, so I will have another try next time I am at the boat.
Thanks for the responses, anyway

 

[voicilesrosbifs]

Echopilot sends 5 volts to the paddlewheel. This may not be enough to get a response - depends on the make of log I guess. In the case of our Airmar (ex-Navman) paddlewheel I tried the Echopilot display and it won't register at all. Going to fix an Advansea log/depth by the chart table - supposedly a replacement for Navman so who knows? It had better work.

 

[William_H]

Paddle wheel transducer

These devices can use a variety of techniques to detect the rotation of the paddle. I had an old Smiths log that had a magnetic reed switch close to where the magnet passes. This was easy to test in that you attach a multimeter on ohms scale to the wires and slowly rotate the paddle. You could see the switch make and break. The magnet got tired and the reed switch would not operate. I fitted a hall effect type transistor which changes conduction as a magnet passes. This worked well but required an additional 5volt supply to the device (plus earth plus signal wire) It is however possible that some hall effect devices can use the power wire as signal wire.
I would not imagine the paddles would use a simple coil because the voltage induced in a coil is proportional to speed. So you don't get much at low speed.
Anyway bottom line it is unlikely an old paddle from a different manufacturer will work with new gear. But you can only ask. good luck olewill

 

[biscuit]

thanks again, all. If i find a solution I will post it for future reference!

 

[biscuit]

For Info:
Echopilot Bronze Plus trio instruments now fitted!
The Old Stowe depth transducer, (through hull and beautifully faired in) IS fully compatible, so no surgery needed. Phew!
The old Stowe paddle wheel log ISN'T compatible, so the old one had to be removed, together with the brass skin fitting, the glassed in nut, the glassed in plywood pad, half a centimeter of resin, and the skin of several fingers.
The hole needed in the hull is the same diameter, though, so refitting is easy!
The Echopilot displays are quite brilliant, and double up as GPS repeaters, so it was all well worthwhile.