at first glance the clock hanging on your wall might not seem special but you'll be surprised to learn just how complex this tiny machine really is let's explore how a clock really works first the clock hands are driven by an intricate mechanism called The Clock movement hidden just behind the clock face this is where the magic of precise timekeeping happens inside the Clock movement we'll find a series of Gear wheels these gears maintain the precise ratios needed to move move each clock hand at exactly the right speed they're driven by a special levette type stepping
motor which is key to keeping everything perfectly in sync stick around till the end and I'll explain how this motor ensures precise timekeeping but first let's take a closer look at how the gear system works first a 12 Toth gear directly connected to the motor rotates in 180° steps every second completing 30 turns per minute this gear drives a 48 Tod gear let's calculate the RPM of the second gear it rotates at 7.5 turns per minute interestingly this second wheel is a compound Gear with a smaller 8 Toth gear attached which also rotates 7.5 times
per minute this smaller 8 Toth gear drives another 60 Toth gear if we calculate its RPM we find that it completes one full rotation per minute the second hand is connected to this gear allowing it to tick precisely every second this 60 toothed gear is also a compound Gear with a smaller eight Toth gear attached that rotates once per minute the minute and hour hands are geared down in a similar way altogether seven gears work in harmony to keep the clock running smoothly now let's dive into the motor that powers all these mechanisms the levette
type stepping motor this Unique singlephase Motor is commonly used in electromechanical clocks though levette's design has inspired many variations Beyond clocks here's how it works like any motor the levette type motor has two main parts a stater and a rotor the rotor is a round magnet attached to a gear wheel like this the stator consists of a wire coil wound around a metal piece the coil receiv receives an alternating current pulse every second from the circuit when powered the metal piece becomes magnetic as the current alternates the magnetic poles switch as well when the rotor
is placed in the middle of the stator it aligns its poles with the magnetic field with the alternating magnetic poles the rotor can align with two positions let's call them A and B but how do we ensure the rotor always rotates in the same direction rather than just oscillating back and forth the key lies in the clever design of the stator's geometry made from ferromagnetic metal the stator natur natur Al attracts the rotor's magnetic poles even when the coil isn't energized if you look closely at the stator's shape around the rotor magnet you'll notice it's
uneven this uneven shape causes the rotor to rotate slightly aligning itself to minimize the distance between its magnetic poles and the stator there are two such stable positions these new positions which we can call C and D are slightly offset from the earlier A and B positions if you try to change the rotor's angle it will always return to one of these rest positions as soon as the force is removed now let's try to explain the rotation here we have not energized the coil and hence the rotor is resting at position D but when we
energize the coil like this the magnetic field created by the coil moves the rotor to position a due to the initial offset it will move to the position a via the anticlock wise rotation and when after energization of the Stater has declined now the stator is just a piece of iron so the rotor moves further until it meets the rest point C again we are energizing the coil from opposite polarity same as earlier due to the initial offset it will move to the position B via the anticlockwise rotation again after energization of the stator has
declined the stator is just a piece of iron so the rotor moves moves further until it meets the rest point D now the motor has completed the one rotation anticlockwise we can repeat this process and make sure the motor always rotates in One Direction you may notice that the coil doesn't need to be continuously powered it only requires two small pulses for each cycle which significantly extends the battery life but how are these precisely timed pulses created that's what we're going to explore next if you look closely at the clock circuit you'll notice a small
cylinder-shaped component this is the crystal oscillator a crystal oscillator is responsible for timee keeping in the clock it works similarly to a tuning fork when you strike a tuning fork it vibrates at a specific constant frequency regardless of how hard it's struck since this frequency is within our hearing range we can hear it however the vibration eventually Fades away to keep it vibrating continuously you'd need to strike it repeatedly at the same frequency as I mentioned earlier the vibration of a tuning fork has a constant frequency meaning each Cycle takes the same amount of time
we can adjust the duration of each cycle by changing the length of the Fork's prongs if we could generate an electrical pulse with each vibration cycle we'd have a perfect timekeeping signal for a clock but how can we get an electrical pulse from a tuning fork we can solve this problem using Peto electric materials Peto electric materials can generate electrical pulses when they are bent if we oscillate a Peto electric strip it produces electrical pulses with a constant frequency but these pulses Fade Away over time not only that when an external voltage is applied to
Peto electric materials they change shape so we can fabricate p Electric strips to bend like this when voltage is applied inside an oscillator there is a pizo el electric strip shaped like a tuning fork it is wrapped with two conductors when we connect a battery to these terminals the pazo electric material bends as soon as we remove the power the material starts to oscillate generating electrical pulses with a constant frequency however these pulses fade over time to maintain continuous pulses we need to turn the power on and off at the same frequency much like striking
a tuning fork repeatedly with a hammer manually controlling this is Impractical so instead we use the electrical signal generated by the oscillator to drive the switch this is done through an amplifier which boosts the oscillator's signal as a result we get a continuous constant frequency electrical clock signal ideal for precise timekeeping but due to size and Fabrication limitations the frequency of a crystal oscillator starts in the kilohertz range in clocks we typically use a 32.768 kerz oscillator meaning it produces exactly 32,768 oscillations every second this number is significant because it equals to the 15th power
of two why is this important this involves a bit of digital Electronics but don't worry I'll keep it simple we use D flip-flop circuits to count the number of Cycles generated by the oscillator if we send the oscillator's pulse into a d flip-flop the output will show a pulse at half the frequency of the input signal the time it takes to complete one cycle has doubled meaning the frequency is haved now if we take the output of the first flip-flop and feed it into another it will again have the frequency the this process repeats with
each flip-flop cutting the frequency in half in a clock circuit we use 15 flip-flops in sequence and by the 15th flip-flop we get a clock pulse with a frequency of exactly 1 Hertz one pulse per second this is how the high frequency oscillator is scaled down to a precise 1 second pulse for timee keeping let's summarize all these systems the crystal oscillator generates a precise 32,00 , 768 HZ electrical signal the counter circuit made of flip-flops reduces this signal to a 1 Herz Square wave the motor Drive uses the 1 Hertz pulse to control the
levette type stepper motor providing the alternating pulses required for its movement finally the motor spins keeping the clock's hands moving precisely the timing of the motor's rotation is entirely dependent on the signal generated by the oscillator which is the Beating Heart of the clock this whole system flip-flop counter motor drive and oscillator feedback is integrated into a single circuit ensuring precise timekeeping and that's how a clock works even though it might seem like a simple device there are many complex mechanisms working together to keep everything running smoothly I hope you enjoyed the video and learned
something new that's all for today if you think my contents are valuable to the world you are welcome to join my patreon community like And subscribe to Professor mad for more interesting videos
