Need help designing a clock with a repeating signal

  • #1
Krion
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0
TL;DR Summary
I need to build a clock that triggers a signal to repeat three times at equal intervals. These intervals need to be adjustable within a short amount of time (i.e. striking three times with 30 seconds in between to striking three times with 90 second intervals).
Hello! I am in need of a clock expert. Just a disclaimer, I am vastly unfamiliar with much of the inner-workings of clocks and need some help. I have only built a simple Graham Escapement clock, previously.

I need to build a clock that triggers a single signal to occur three times at equally spaced time intervals. These time intervals need to be adjusted after each trial for a total of three trials (we are only given five minutes to adjust). We are also only limited to mechanical clocks and no electrical components. I was looking into striking clocks, but I am unsure of whether you are able to adjust the interval at which it strikes or if it is even doable considering my inexperience. I have also considered adding a lever system that triggers a visual signal, but the dropping weight does not strike the lever with enough force to trigger it. Currently, I am trying to research more into it, but I find it hard to understand a lot of material. A bit of advice would be greatly appreciated!
 

Answers and Replies

  • #2
Baluncore
Science Advisor
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6,203
Welcome to PF.

I think you need to keep it simple.
1. A pendulum and an escapement wheel.
2. A 12 tooth bicycle chain pinion on the escapement shaft.
3. Adjust the pendulum length to one pinion tooth per second.
4. A weight hanging on a length of bicycle chain drives the escapement shaft.
5. The signal is triggered when an extra-long roller pin passes over the top of the pinion. The distance between three long pins in the chain programs the period. It all stops when the weight reaches the floor.

Also, consider a loop of chain with only one extra-long roller pin. It will regularly pass over the pinion, with a period determined by the number of links in the chain loop. A separate weight would be required to drive the escapement shaft.
If more than three signals were not permitted, then the weight would have to be caught after three and a half periods.
 
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  • #3
Tom.G
Science Advisor
Gold Member
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A really odd approach:
  1. consider a spoon. you hold the handle in your fingers and twirl it so the bowl spins with the spin axis along the handle
  2. if you put the spinning bowl in a container of liquid it will be harder to spin
  3. the more of the spoon bowl in the liquid, the harder it is to spin
Now if you use a liquid that is more viscous ("thicker") it will be even harder to spin that spoon. That could be a way to control the spin speed if the driving force is fairly constant. A constant driving force could be a weight suspended by a string that is wrapped around a shaft, or the spring from a sacrificed windup clock (probably harder to use though).

For the different time periods that you need, you can change how deep the spoon is in the fluid; or use different size spoons; or wrap the string supporting the weight around different diameter shafts.

Now getting really odd, instead of a liquid, use silly putty and adjust its viscosity for different speeds.

You can make silly putty using corn starch or using borax powder. Do a Google search for: make silly putty.

Anyhow, there is one approach to a speed regulator. The rest of the mechanics "Are Left To The Reader." :oldbiggrin:

Have Fun!... and please keep us updated on your project, it sounds like a fun one.

Cheers,
Tom
 
  • #4
sophiecentaur
Science Advisor
Gold Member
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Raspberry Pie?
(Only joking)
 
  • #5
anorlunda
Staff Emeritus
Insights Author
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We are also only limited to mechanical clocks and no electrical components.
Thanks for the reminder. In today's world we are accustomed to software-based solutions that make things like that trivially easy. We forget how difficult it was to be flexible using mechanical solutions.

Is this a challenge posed to ME students?
 
  • #6
Krion
2
0
Welcome to PF.

I think you need to keep it simple.
1. A pendulum and an escapement wheel.
2. A 12 tooth bicycle chain pinion on the escapement shaft.
3. Adjust the pendulum length to one pinion tooth per second.
4. A weight hanging on a length of bicycle chain drives the escapement shaft.
5. The signal is triggered when an extra-long roller pin passes over the top of the pinion. The distance between three long pins in the chain programs the period. It all stops when the weight reaches the floor.

Also, consider a loop of chain with only one extra-long roller pin. It will regularly pass over the pinion, with a period determined by the number of links in the chain loop. A separate weight would be required to drive the escapement shaft.
If more than three signals were not permitted, then the weight would have to be caught after three and a half periods.
That is very helpful. Thank you so much!
 

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