Help-Want to automate the ringing of my gong

I use 12 volt solenoid valves on my crop sprayer. They will move a magnetic object about 1/2" with several pounds of force. A linkage to your gong and a spring to pull it back should do the trick.

I'd let you have one with worn seals pretty cheap. karltownsendembarqmailcom

Karl

wrote: (clip)what can I use to activate the gong stick (clip) ^^^^^^^^^^^^^^^^ There are lots of ways you could do this. One very important consideration is that the "clapper" should hit the gong and immediately rebound. I would put a spring in the system so the skateboard wheel overtravels on the power stroke, and then pulls back immediately. The system that comes to mind is this:

Use a 12v gearmotor, with a scroll-shaped cam on the shaft. Set it up so that as soon as it starts to turn, it drops the clapper, and the gong rings. Now the cam continues to turn, drawing the clapper back to the "cocked" position. Wire it so a switch stops the motor just before it drops the clapper again.

So, the sequence is: 1.) Doorbell button pushed. 2.) Latching relay closes, starting motor. 3.) Clapper drops and rings gong. 4.) Motor completes one revolution, rewinding the clapper and opening the latching circuit. 5.) Relay opens, motor stops, with clapper hooked on the corner of the cam, ready for the next round.

That sounds like a nifty door bell. I like it. I'd try to use an automotive starter solenoid to drive the dowel and wheel into the gong. The power for the solenoid could be provided by a little lead acid battery that gets charged by the solar cells. The original return spring could be replaced with a weaker one.

Jerry

Jerry

Alarm system motion detectors usually are 12 v and have contacts for normally open/normally closed circuits. Wired with a 12 volt source, and a 12v solenoid designed to break the circuit as soon as it's energized should do it. The only thing I'm not sure about is how to keep the motion detector from "repeating" the ringing at every movement. Ken.

I've got this issue on my driveway alarm. I just put a timer in that lets current to the bell for 0.5 seconds and then holds it out for 50 seconds.

Karl

On Sun, 17 Jun 2007 11:18:52 -0700, with neither quill nor qualm, gome@home quickly quoth:

To allow the gong to resonate, you'll need to have the striker hit it and immediately withdraw. A solar battery charger connected to a windshield wiper motor will do a single rotation which can be operated from a momentary switch. Use a cam on the wswm output shaft to drive a spring-loaded striker stick. Time it so the spring lets go just as the cam gets to the highest point. Time the spring release to move out of the way by using the return of the cam in the other hemisphere. this will allow the striker to return to the loaded position.

The concept is to bend the striker stick until it pulls loose from a retaining spring, allowing the gong to be struck. Another spring returns the striker to the loaded position. As the cam comes back around the bottom side, it lifts the retaining spring to allow the striker to fully settle.

Describing the picture I have in mind isn't as easy as I thought it would be. I'll draw you a picture if you like. Ping me offline.

------------------------------------------------------------------------- Poverty is easy. *

-------------------------------------------------------------------------

I was very disappointed after reading the header and then finding out the post wasn't about sex.

WOW... Thanks for all of the great ideas... I have the solar 12v charging dialed... the 12v motion detector can be had off the self for not much (did not know that, thanks)... the motor cam idea to many moving parts possibly, but can see it working much like the modern trebuchet designs with a DC motor and that would be cheap and small... solenoid ? Thank You - Thank You I did not know what the name of the thing was but much like a sprinkler valve solenoid in working so I like the auto solenoid idea and will work on that in this week... I should be able to get one cheap... the problem with that is it may be too large as I would like the whole array to be positioned inside the bell and hidden from view... so a small off the self (as Ken mentioned) solenoid push or pull 12v 10 lbs. ? single coil or double would do the trick and it looks to be under $30 or so... the point was mentioned about it going off to often and driving me crazy... so I am thinking a 555 timer circuit & relay and it could be set for when ever...

" The power for the solenoid could be provided by a little lead acid battery that gets charged by the solar cells. The original return spring could be replaced with a weaker one. Jerry"

The solenoid would have to be energized and then immediately withdraw as the sound is compromised if anything touches the bell even hitting it twice in rabid succession screws it up... so with an auto solenoid the turning of a key does the trick ? what can I use to triger the solenoid of a split second while a spring returnes the arm...

Once again TIA for all of your help...

According to :

One way is a slow-acting relay (perhaps a capacitor across the coil and a resistor in series) which will interrupt the power to the solenoid after a moment until the button is released. Slow-acting relays were common in telephone exchanges, with a solid slug of copper around the pole piece towards the moving armature causing delay in actuate time, and a solid slog of copper around the base end of the pole causing it to be slow to release. If you wanted both effects, you put a solid sleeve of copper around the full length of the pole and wound the coil as a second layer above that. In all cases, the slug of copper acted as a shorted turn, slowing down changes in the magnetic field. The slow-to-energize and slow-to-release forms were easy to recognize by sight, but the slow-for-both were harder to tell, because the slug was hidden under hundreds of turns of copper wire and layers of insulation.

Another trick, if you have the right specialized relays on hand, would be the ones with make-before-break contacts, and apply power from the button between the NC and NO terminals, so they are powered for an instant as the relay transitions from un-energized to energized positions. There are various designs of make-before-break contacts, but they are normally drawn in schematics like this (view with a fixed-pitch font to avoid distortion which might confuse the meaning):

NO o--------------------- NC o-------+ ^ V | COIL C o----------+ HERE

so -- as the relay is actuated, it pulls down the NO contact blade, which touches the points on the C at the bottom, making a connection through that to the NC contact blade. Once it makes the contact, it keeps moving, moving the C blade (which also flexes) away from the NC blade (which is rigid).

Normally, the C is connected to something, but in this case it is left floating, and just assures that the power to the solenoid is of short duration. The power comes in the NO blade from the relay coil, so it is energized only when the doorbell button (or motion sensor) is pressed/activated. This way, you don't get another pulse when the button is released.

Or -- you could use the solenoid to accelerate the plunger with the roller skate wheel towards the gong, and have the solenoid hit a rigid stop before the wheel makes contact, so it will simply keep flying to hit the gong, and then bounce off, being assisted by a light spring to bring it back into contact with the solenoid. That way, you don't need to interrupt the power to the solenoid at all -- other than to perhaps keep it from overheating if the motion sensor keeps it energized for too long.

Enjoy, DoN.

and have the solenoid hit a rigid stop before the wheel makes contact, so it will simply keep flying to hit the gong, and then bounce off, being assisted by a light spring to bring it back into contact with the solenoid.

Thanks Don this is a good idea... as for the S I am hoping for an off the shelf deal and am not ready for the relay just yet... I would like to design this thing around the solenoid first... Gome