Rigging up electric bell under platform

What is striking the bell now? There's a lot of possibilities.

A rotory motor ( your stuck adding a coil type most likely) or linear motor (coil) etc etc?

A picture of what you have would be nice. Voltage? AC? DC?

Exactly what do.you wish to replicate?

You might be able to slow a rotary, but not get just one hit; that's harder. A stiff arm off the armature with both sides of the bell as stops along with polarity reversing is possible I suppose. ...Or a spring return I guess.

Coil and arm "rocker"?; is it one coil&spring-return, or two coils? Are they on a linear mount? Or coil(s) moving an arm?

Off hand, as an external striker for a 4" bell, maybe a momentary on toggle and a power door lock solenoid for a car, lol. But a little research on linear motors will get you something too. Pinball and coin op supply is a decent route to chase coil parts.  Train accessory coils, if you had any, too.

Regulating a coil strike can be done with capacitors, and or relays, and or momentary switches. If a cap is used, you might need to say "how long is the minimum rest period between bell strikes going to be?". Relays might be used to ensure a "snap" action too.  Old, two chime, ding dong doorbells usually have a dampening setting that can be applied to a chime mechanically. One bell being removed was another option.

Point is, it can likely be done; whatcha got in front of you now?

I used to relly like doorbells as a kid. Large houses might use AC and or DC + - to trigger door specific chimes on not just one chime set, but various. My aunts place had a control panel in the kitchen and hall so the bells could be turned on and off in the bedroom halls or servants quarters. Even our little 3 bed suburban bungalow had 1 chime ring for the back door and 2 for the front.

Right now, I have nothing.  I would be fine running off of the transformer or household current, I have access to either.  What I want, in the end, is to have a doorbell switch at the same location as my transformer, so that I can operate a trolley and be able to signal with an actual bell mounted out of sight.  It should operate the same as a single chime doorbell, one strike per push of the button.

Cheap door bells do have strikers and operate like I would want, but the tone is way off and I am doubtful that the same strike could be adapted to one of the 4" bell models.  

As I am thinking about this, I am remembering that there were postwar switcher engines with slopeback tenders that had ringing bells.  Not the easiest to come across and I have no idea how toylike the bell sounds.  I want a full bodied clang like at a boxing match.  There were also prewar crossing signals with bells but I have never seen one operate.

You bought a door bell. You need a door chime.

http://www.doorbellsdirect.com...su.html#.WDOhNdQrJkp

PLCProf posted. If it is a plain old cheap "buzzer style," doorbell, there is a set of contacts in series with the coil to make it ring continuously. Just wire around those contacts and you should be set to go.

Like this kind?

I didn't buy anything yet.  

Since it is hidden "out of sight" is it important that it be a mechanical bell and clapper?  With modern hi-fidelity and inexpensive MP3 audio devices you might not be able to hear the difference...and would give you ability to change sounds for variety.   After all, your trolley itself is too a model of the prototype.  Just asking...

I'd really rather something mechanical.  

The one shown above will probably have three terminals inside, marked "A" "D" and "C".   Normally, if you want it to ring continuously...as long as the button is depressed...you decide which type of current you want to use (AC or DC) and use the appropriate pair of terminals.

If you want it to make "one ding only" you can force it to do that, by using DC on the "A-C" set of terminals. When the button is depressed, one pulse of DC will cause the clapper to move and strike the gong once. When the button is released, the clapper returns to the home position and waits for the next impulse. 

If you want it to make what you refer to as a "traditional 1/2 chime" (I suspect you mean one that makes a "ding-dong" sound) then you need to buy one such as in the link that I provided. It has two gongs, and a spring-loaded double-acting pin that first is pushed against a spring, hitting the high-pitched gong, then when the power is released, it returns to the home position striking the low-pitched gong.

I have one like this somewhere, it's about 8 or 9 inches in diameter.  The sucker is LOUD!

Arthur, that should work.  A typical trolley bell would be mono-tone so I would only need the 'ding' and not the 'dong.'  It's a small investment to give it a try.  

Remember that you need to use DC, on the "A & C" terminals. If you use the D & C terminals, it will ring continuously.  You can make DC by putting a diode in series with one of the leads.  

If you haven't bought yet, you have plenty of options

The "bell ringers" were like a bicycle bell, "trolley like" tempo, but not very loud.

Volume will very much have to do with bell size as much as strike.A fire bell, new or old, wouldn't be a bad place to start for a loud one, IMO.

Montclaire posted:

I'd really rather something mechanical.  

A mini ship bells of all sizes can be found on a mount if you wanted. Some even have pullys or swing arms.

A desk bell can be found 4" and as large as 6".

I saw a few interesting 4" trolley bell door knockers for sale by various folk on "an auction site".

An old boxing bell would have a manual throw too.

Electric school/fire bells are a dime a dozen $10-30, 4"-8"

Arthur P. Bloom posted:

The one shown above will probably have three terminals inside, marked "A" "D" and "C".   If you want it to make "one ding only" you can force it to do that, by using DC on the "A-C" set of terminals. When the button is depressed, one pulse of DC will cause the clapper to move and strike the gong once. When the button is released, the clapper returns to the home position and waits for the next impulse. 

Interesting thought.  I've got the exact bell shown above - it's a universal design, though, so AC and DC produce the same results. The clapper is attached to one of the contacts - so when it moves to ring it opens the circuit, returning the clapper to its original position and the cycle repeats.

PLCProf posted:

If it is a plain old cheap "buzzer style," doorbell, there is a set of contacts in series with the coil to make it ring continuously. Just wire around those contacts and you should be set to go.

I wired up my bell as PLCProf suggested, using a bridge rectifier to provide constant DC (a diode alone won't hold the clapper on the negative AC half-wave...).  It works, to a degree - but then the clapper ends up against the bell which mutes the ringing.  One needs a NO instantaneous switch that only closes for a fraction of a second to energize the coils and then quickly opens again - is such a thing commonly available (perhaps something like a BBQ electronic ignition switch)?  Or, alternatively, is there a relatively-simple, clever circuit that would perform this?

JTrains posted:

Or, alternatively, is there a relatively-simple, clever circuit that would perform this?

One solution I came up with this morning is to charge a 4700mF electrolytic capacitor and then discharge it to the bell.  The amount of energy released is just about right to get a single solid "ding".  Using a momentary DPDT switch, one could have the capacitor charge from a DC power source when the button is released and then discharge to the bell when the button is pushed. The capacitor charges quickly enough that you can repeatedly push the button about once a second to get the cadence of ringing that is desired.

I should probably, though, have a think about the ripple current of the approach - but I'm still on my first cup of coffee.

How about an old Marx bell ringer? I remember when I was a youngster it would drive my parents nuts early in the morning when I was running the trains. JAck Tylenda

trooperty@comcast.net posted:

How about an old Marx bell ringer? I remember when I was a youngster it would drive my parents nuts early in the morning when I was running the trains. 

If we're talking about the same thing, I've got one of those - but it's also a "continuous ringer" type, although perhaps it could be modified to produce single rings akin to what I've done above.

That sucker is indeed loud - it rings so forcefully I've had mine walk itself across the floor!

Perhaps you only need a momentary ON-(ON) SPDT?  For voltages/times you've mentioned a small R in the 10 ohm range could limit current while re-charging fast enough.