Project help request: Striking a bell manually, alarm clock.

[stevef22]

Hello! Glad to be here at this forum. My name is Steve. I'm looking for help designing a circuit for an alarm clock bell. The bell is a "singing bowl" struck with a leather mallet.

Variables user can set:

Initial Clock time
Clock Time Zone
Chimes: 1-10
Duration between chimes: .100ms - 5 seconds
Intensity of strike: (not sure how to rate this, ie harder or softer)

Design goal is for a physical mallet to strike the singing bowl via actuated 12v motor. (I can get fancy and design a little wooden figure to strike bowl later)

I'm thinking the clock settings can be built into wooden base via a small analog LCD screen. Or everything configured via super basic app with the above variables listed above, connected via bluetooth.

My idea isnt novel. This gentleman created a similar invention. Link here:

If interested in helping me please let me know! My skills are soldering, wood working and finishing. Looking forward to your reply!

Simple image diagram of my project: https://ibb.co/g4bLJQj

Thank you, Steve

 

[rjenkinsgb]

I can see a couple of options for the mechanical system:

A solenoid rather than a motor, to operate the mallet:

The striker for a bell or gong usually needs to be "floating" so it bounces away again after a strike, otherwise it mutes the bell.

By varying the pulse duration to a solenoid you could vary the force and so how hard it nudges the striker, then the striker is "thrown" at the bowl by that impulse and can bounce back, with a spring to hold it against the solenoid when idle.

Varying a pulse time or duration is very simple with a microcontroller, as they pretty much all have internal timers.


A motor could do the same thing, but using it as a rotary solenoid in effect, directly swinging the striker & with spring return rather than continuous rotation.

A normal DC motor may not work well for that, as the brushes would be in the same area permanently, but possibly a brushless motor with one winding directly switched & the mallet mount angle set appropriately could work well?

The electronics & clock side is relatively simple, with an appropriate MCU.

 

[For The Popcorn]

A hobby servo might work.

 

[danadak]

Spring loaded door striker :

Regards, Dana.

 

[stevef22]

Hello! Thanks for the input! Would this work?

 

[stevef22]

I can see a couple of options for the mechanical system:

A solenoid rather than a motor, to operate the mallet:

The striker for a bell or gong usually needs to be "floating" so it bounces away again after a strike, otherwise it mutes the bell.

By varying the pulse duration to a solenoid you could vary the force and so how hard it nudges the striker, then the striker is "thrown" at the bowl by that impulse and can bounce back, with a spring to hold it against the solenoid when idle.

Varying a pulse time or duration is very simple with a microcontroller, as they pretty much all have internal timers.


A motor could do the same thing, but using it as a rotary solenoid in effect, directly swinging the striker & with spring return rather than continuous rotation.

A normal DC motor may not work well for that, as the brushes would be in the same area permanently, but possibly a brushless motor with one winding directly switched & the mallet mount angle set appropriately could work well?

The electronics & clock side is relatively simple, with an appropriate MCU.

Would this door striker be compatable with pulse time and duration? Thank you

 

[danadak]

Yes, you experiment with pulse width to get the effect you need. If you are programming.

Keep in mind you drive it as follows from micro :

Regards, Dana.

 

[Inquisitive]

Use an old electro-mechanical door bell striker kit. Like the ones used in houses?

 

[schmitt trigger]

Use an old electro-mechanical door bell striker kit. Like the ones used in houses?

That would also be my recommendation.

 

[For The Popcorn]

This is what has been suggested – a striker from an old style mechanical 'ding dong' door bell. These are a lightweight, spring-loaded solenoid mechanism with plastic tips. They automatically retract back to the neutral position.

Give it a short pulse, you'll get a light tap. A longer pulse, a harder tap. Longer still, it will tap and stay in contact with the bowl for the duration of the pulse.

 

[rjenkinsgb]

I was thinking of a "push" solenoid such as this:

12V DC 10mm Long-stroke Solenoid Electromagnet Electric Push-Pull Actuator 0530 | eBay

Find many great new & used options and get the best deals for 12V DC 10mm Long-stroke Solenoid Electromagnet Electric Push-Pull Actuator 0530 at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[Nigel Goodwin]

Use an old electro-mechanical door bell striker kit. Like the ones used in houses?

Which is basically what he's making

 

[stevef22]

Sorry for the late reply. It took me a little while to order parts. First Solenoid ordered was too small with 10mm of travel. The brass tip of the 10mm solenoid sounded bad against the metal bowl, putting rubber on the end did not help. So I went with a 30mm travel larger solenoid to actuate the mallet.



Here is where Im at!

Picture Full Size: https://ibb.co/HCz0bcH




Part: Solenoid 35mm Push Pull 12V

https://www.amazon.com/dp/B07G15X91N?psc=1&ref=ppx_yo2ov_dt_b_product_details

I can manually make it go GONG when I momentarily connect the terminals to my power 12V 8A power supply. Work and sounds great!





Next Steps:


How would I program this into an alarm clock? I need a program to control the 12V 8A current with clock function. I can pay for your design help. Please PM me or reply here.



Features:


- Set time


- Set alarm time


- Set number of chimes





*There is no turn off function like typical alarm clock. You can just set number of chimes.














Thank you, your help is much appreciated.