Something weird going on with the electrics

[Lucky 1]

I have noticed that when I take the tinny out at night, if I turn the anchor light off, it still turns on slightly with the transducer pulses. It only happens when the sounder is turned on. I have an old Hummingbird if anybody feels this is relevant.

I would expect it would be a grounding issue, however I cannot see how the transducer cable could be earthed inadvertently? wouldn't this affect the performance of the sounder?

Thanks for any feedback provided in advance,

Cheers

Lucky

[Noelm]

not 100% sure what is going on, but as a wild guess, I would think someone has used the boat as an earth like you do in a car, and somehow that is causing the problem, the transducer is kind of earthed anyway, via the outer braid in the cable, that is earthed to the unit, that is earthed to the battery (or boat)

[Noelm]

Mind you, it is ever so remotely possible that the tranducer cable is laying next to your other cables and via induction it is producing a minute voltage to your light.

[Lucky 1]

Yes, thanks Noelm I was thinking induction might be the cause of the troubles, as we have a fluctuating electrical field. Sounder unit is not earthed, apart from the negative terminal via a bus bar on the battery. I have done theelectrics myself(perhaps part of the problem lol). I might try to isolate the transducer cable as much as possible from the rest of the wiring.

[juggernaut]

I'm thinking induction as well.

Had a similar problem when I was into modifying cars. To tidy up the engine bay I ran the temp sender wire in the same sheath as the electronic ignition wires to the distributor and it played havock on the engine misfiring etc when it got warm. The pulses in the temp sender wire increased as water temps increased (as tested by my test light) which intereferred with the distributor firing the plugs. Just removed the temp sender wire from the sheath and all was good.

[Fed]

Pretty tricky when you consider temp sensors don't pulse.

[juggernaut]

Pretty tricky when you consider temp sensors don't pulse.

So what do pulse width modulated square wave frequency senders do then?

[Fed]

No idea Juggernaut but it sounds pretty exotic for a car temperature sensor.
What sort of car was it in?

[Andy H]

They warm up the flux capacitor.

[juggernaut]

No idea Juggernaut but it sounds pretty exotic for a car temperature sensor.
What sort of car was it in?

Pulse type senders (not sensor) are not exotic at all - typically used in pre-EFI cars.

1979 Escort RS2000

1979 Spitfire temp gauge...getting pulse output from sender unit.

http://www.oocities.org/motorcity/sp...tempgauge.html

Pulse output from fuel gauge sender.

http://vintage-vans.forumotion.com/t...-gauge-voltage

Also I think you may be confusing a sensor with a sender

[Fed]

Thanks juggernaut I had no idea senders pulsed, always thought they were purely a resistance that varied with temperature.

[juggernaut]

, always thought they were purely a resistance that varied with temperature.

Correct - with a pulse voltage, in my case, present in the in temp sender restistance wire - refer my original post.