How to make this, clock that can speed up or slow down

Thread Starter

rzzyf

Joined Oct 11, 2023
4
I want to make a clock that can speed up or slow down based on the position of the a piece that can be rotated around on the same clockface. when its at the top, the clockhand will spin fast, and vise versa, and when it's in the middle section its medium speed. is it possible? how to do it?

IMG_20231010_172246.jpg
 
Last edited by a moderator:

LesJones

Joined Jan 8, 2017
4,172
Use the rotation of the speed control to drive a crank. Have a connecting rod between the end of the crank and sliding potentiometer. the length of the crank would need to be a bit less than half the travel of the potentiometer. You could use a normal rotating potentiometer with a longer crank than the crank than the first crank.
Another solution would be to use an absolute position encoder (Such as a grey code encoder.) and use the output value to control the speed. If for example you used an 8 bit encoder you would use bit 7 to invert the value from bit 0 to 6.

Les.
 
Last edited:

BobTPH

Joined Jun 5, 2013
8,664
I presume you are seeking an electronic solution, not mechanical, since this is an electronics forum

Way too many possibilities.

Does the slider have to be able to move through the entire circle, or can it have stops on both sides, like an old fashioned volume control?

Does it need continuous variation, or are a few steps OK? If so, how many?

How many hands, your drawing shows only one?

What range of speeds?

What experience do you have?

analog circuits (opamps)?
motor speed control?
stepper motors?
sensors?
digital logic?
microcontrollers and programming?
 

Thread Starter

rzzyf

Joined Oct 11, 2023
4
I presume you are seeking an electronic solution, not mechanical, since this is an electronics forum

Way too many possibilities.

Does the slider have to be able to move through the entire circle, or can it have stops on both sides, like an old fashio
ned volume control?

Does it need continuous variation, or are a few steps OK? If so, how many?

How many hands, your drawing shows only one?

What range of speeds?

What experience do you have?

analog circuits (opamps)?
motor speed control?
stepper motors?
sensors?
digital logic?
microcontrollers and programming?
I did some research, and found that electrical would probably work best, but Im completely unfamiliar with it.

I would prefer that the slider be able to move the whole circle, with the speed changing depending on the position of the slider. I think around 6 speeds(sections) would be sufficient.

Im not sure what I would need to make this happen, but Im willing to learn
 

Thread Starter

rzzyf

Joined Oct 11, 2023
4
Use the rotation of the speed control to drive a crank. Have a connecting rod between the end of the crank and sliding potentiometer. the length of the crank would need to be a bit less than half the travel of the potentiometer. You could use a normal rotating potentiometer with a longer crank than the crank than the first crank.
Another solution would be to use an absolute position encoder (Such as a grey code encoder.) and use the output value to control the speed. If for example you used an 8 bit encoder you would use bit 7 to invert the value from bit 0 to 6.

Les.
Use the rotation of the speed control to drive a crank. Have a connecting rod between the end of the crank and sliding potentiometer. the length of the crank would need to be a bit less than half the travel of the potentiometer. You could use a normal rotating potentiometer with a longer crank than the crank than the first crank.
Another solution would be to use an absolute position encoder (Such as a grey code encoder.) and use the output value to control the speed. If for example you used an 8 bit encoder you would use bit 7 to invert the value from bit 0 to 6.

Les.
I tried drawing out what that would look like, please correct me if it doesn't look right:
IMG_20231012_011617.jpg
Im completely new to electronic engineering, so Im not completely sure how a potentiometer works. Do I connect it to the clock hand? how would it power the clock and does it need batteries??
 

MisterBill2

Joined Jan 23, 2018
17,814
Given that we were given no hint as to what sort of clock mechanism is involved it is unlikely that much detail can be provided. So really it is a poorly posed question, given with no context.
A reasonable guess is that the clock has some sort of electric motor drive that is regulated by some sort of stable frequency reference. So the mechanism of changing the speed would be to change the frequency of that reference, That can be a simple voltage controlled oscillator circuit.
The second guess is that the clock rate is intended to be manually adjustable rather then to depend on the indicated time. That makes the task much simpler. The face with the numbers would be some translucent material so that light would pass through, and the manually placed marker would block some portion of the light passing through, with the variation detected by a photo-resistive cell on the other side of the face. The variable resistance then will adjust the voltage to the variable reference oscillator.

A much more interesting version would adjust the speed based on the position of the hour or minute hands of the clock. That could be a bit more complicated as far as sensing goes.
 

LesJones

Joined Jan 8, 2017
4,172
I think your drawing shows my first suggestion. (It is like the cranksaft, connecting rod and one piston of a car engine.)
As MisterBill2 says you have not provided enough information. Do you want to just change the speed by a few PPM ? (like the trimming capacitor on the crystal in a quartz clock) Or do wou want a wide range of speed such as 1 ms per rev to 1 rev in 100 years ? The potentiometer wil give an output to a circuit that will control the speed of the motor which would be driving the single hand shown in your first post. You will need to give us information on the motor that you plan to dtive the hand.

Les.
 

MisterBill2

Joined Jan 23, 2018
17,814
I think your drawing shows my first suggestion. (It is like the cranksaft, connecting rod and one piston of a car engine.)
As MisterBill2 says you have not provided enough information. Do you want to just change the speed by a few PPM ? (like the trimming capacitor on the crystal in a quartz clock) Or do wou want a wide range of speed such as 1 ms per rev to 1 rev in 100 years ? The potentiometer wil give an output to a circuit that will control the speed of the motor which would be driving the single hand shown in your first post. You will need to give us information on the motor that you plan to dtive the hand.

Les.
Much more fundamentally, the TS has not mentioned what variety of drive mechanism is inside that clock. Is it a mains powered synchronuse motor? Or one of those electronic drive escapements? Or a battery wound mechanical movement like was used in automotive car clocks in the era before electronic digital clocks? Or some other type? My scheme will work with most clocks driven by a constant frequency oscillator., although the frequency range will need to be different for different types.
It does seem like an interesting project,good for a lot of laughs in some venues.
How about a clock that slows down at noon so that lunch time is perhaps stretched to 75 minutes from the standard 60 minutes? And then it runs faster so that by 3 PM it is correct? That could be a great selling product in some areas.
 
Top