Alarm bell for bilge pumps. & swap yanmar buzzers to bell.

[DogWatch]

I already have light indicators on the helm for my bilge pumps, but would also like a sound alarm, I prefer bells to electronic alarms and have found a few (mostly fire bells) that will run from the 12v dc supply.

Such as this one

This is easy enough, just connect the bell across the auto switch, would not want to come on when manually pumping the bilges.

Now the more difficult but.

I hate the buzzers on my yanmar panels, so unrefined.

So I would like to use the same bell (if possible) to replace the piezo alarms on the two engine panels. I don't see any reason to have more than one bell, if the bell sounds I will still have lights indicating port bilge/stbd bilge/port engine oil/stbd engine oil etc etc.

I believe the peizo is part of the alternator exciter circuit, if I add a higher current item to excite the circuit, does this matter? Will it shut down the bell when the engine begins charging?

Will attempting to share a single bell across 4 circuits be a problem, will I need 1 bell per engine to work correctly (this I suspect).

Any other problems?

 

[nimbusgb]

1 bell, 1 diode per 'fault circuit' and 1 small relay. Problem solved.

The piezo sounder used on the existing panels may be current limited so you might have a problem driving even a small relay from its circuit ........ but I doubt it.

You'll need to know if the piezo circuit is active 12v ( 24v? ) or active ground and may have to adjust where you wire in to the float circuit to match.

Late night on watch, small amount of water in bilge.

6" alarm bell sounds.

On duty watchkeeper falls over side with fright!

 

[prv]

The Yanmar GM-series panel circuit diagram is online (don't have a link to hand right now, but it's been posted here before). It's pretty simple beast.

The "not charging" warning light isn't connected through the buzzer, presumably for exactly the sort of reason you were worried about with your bell.

From memory, the other two warning circuits run from the general panel positive, through their respective lights, to the sensor, which connects to ground when alarmed. The buzzer is in parallel to the lights, but has a pair of diodes after it to prevent all the lights earthing through a single sensor at the point they all connect to the buzzer.

Subject to wire sizes etc, I think you should be able to do a straight swap of buzzer for bell.

Pete

 

[DogWatch]

The Yanmar GM-series panel circuit diagram is online (don't have a link to hand right now, but it's been posted here before). It's pretty simple beast.

The "not charging" warning light isn't connected through the buzzer, presumably for exactly the sort of reason you were worried about with your bell.

From memory, the other two warning circuits run from the general panel positive, through their respective lights, to the sensor, which connects to ground when alarmed. The buzzer is in parallel to the lights, but has a pair of diodes after it to prevent all the lights earthing through a single sensor at the point they all connect to the buzzer.

Subject to wire sizes etc, I think you should be able to do a straight swap of buzzer for bell.

Pete

That's interesting, when I thought up the original question in the OP, I hadn't considered the other circuits. Good to know the buzzer/screamer is in parallel though, should really make life simple.

Will have to draw it out and hope to see if there might be a problem sharing a single bell for four alarms. I suspect nimbus is correct with the addition of relays to keep the current down. I plan to fit it within the steering console with should muffle some of the 83db urgency fire bells generate.

I did find a much better miniature bell but that had a max 10v input, I guess I could use this with a zener strapped to the supply.

 

[prv]

I suspect nimbus is correct with the addition of relays to keep the current down.

I strongly suspect that's unnecessary unless you have a serious bell. The back of a basic 2GM20 "A" panel is not a delicate piece of electronic tracery, it's a key-switch rated to 30 amps plus a bundle of chunky wiring, bullet connectors, and torch bulbs.

All bets are off if you have a newer panel (I've never seen the back of one), but the old ones are as simple and robust as a brick.

EDIT: Unless you're talking about pulling the actual bilge-pump current through the engine panel somehow. Agree that's not a good idea.

Pete

 

[DogWatch]

EDIT: Unless you're talking about pulling the actual bilge-pump current through the engine panel somehow. Agree that's not a good idea.

Pete

No, I would just take a +12v off the other side of the float switch.