Hello, I have a, lets call it an art project, I want to make. I have some electronics experience, but no circuit design experience. What I want to do seems so simple, but I'm not sure the best way to do it.

Essentially I want to take a cheap quartz clock mechanism and make the seconds hand tick more frequently, maybe 2 or 3 or 4hz (I would go faster but I want to keep the battery life decent). I'm not making a clock, so accuracy is not important.

I already have the clock I want to modify, it's a ticking style, not the smooth motion style clock, and runs off of a single AA battery. I poked around at the circuit and I can see that the IC has two outputs for the two sides of the motor and they pulse alternately to 1.5 volts at .5hz. The pulse width is very small, looks like a spike.

I've thought I could change the crystal, change the IC, or create a new circuit. I doubt I could find a crystal for my desired effect, and I'm not good at shopping for IC's, so I'm leaning toward building my own circuit, or having someone tell me what IC to use. As I'm researching circuit design I'm seeing a lot of stuff with 555 timers and things that require 5 volts. I would really like to use the clock in its original form, so that means having everything run off of 1.5 volts. Also, cost is a factor, if the first one works out I'd like to make multiples at a reasonable price.

Any recommendations on how I should proceed?

 

Hello, I have a, lets call it an art project, I want to make. I have some electronics experience, but no circuit design experience. What I want to do seems so simple, but I'm not sure the best way to do it.

Essentially I want to take a cheap quartz clock mechanism and make the seconds hand tick more frequently, maybe 2 or 3 or 4hz (I would go faster but I want to keep the battery life decent). I'm not making a clock, so accuracy is not important.

I already have the clock I want to modify, it's a ticking style, not the smooth motion style clock, and runs off of a single AA battery. I poked around at the circuit and I can see that the IC has two outputs for the two sides of the motor and they pulse alternately to 1.5 volts at .5hz. The pulse width is very small, looks like a spike.

I've thought I could change the crystal, change the IC, or create a new circuit. I doubt I could find a crystal for my desired effect, and I'm not good at shopping for IC's, so I'm leaning toward building my own circuit, or having someone tell me what IC to use. As I'm researching circuit design I'm seeing a lot of stuff with 555 timers and things that require 5 volts. I would really like to use the clock in its original form, so that means having everything run off of 1.5 volts. Also, cost is a factor, if the first one works out I'd like to make multiples at a reasonable price.

Any recommendations on how I should proceed?

I’d review your requirements. Your finding a solution that only requires 1.5 volts will be difficult, if damn near impossible.

 

I’d review your requirements. Your finding a solution that only requires 1.5 volts will be difficult, if damn near impossible.

Why do you say that? There are many MCU's that will function on that supply voltage. As an example, many members of the TI MSP430 family.

 

I’d review your requirements. Your finding a solution that only requires 1.5 volts will be difficult, if damn near impossible.

Well, if that's the case then what would you recommend?

Should I add another AA battery to get 3V, step it up to 5V to run the logic and then step it down to 1.5 to drive the clocks original motor? Or is there logic that runs at 3V? should I forget about the clocks motor and replace that too? I'm just trying to rotate a piece of paper, pretty slowly, so I'm mostly worried about efficiency, not torque or speed. What is the most efficient low voltage, low speed motor/driver setup? DC motor, stepper motor?

What really drew me to this idea is the impressive battery life of these clocks, I thought even if I cut it in half or quarter it it would still be pretty good, but if I have to replace all the components, that's out the window.

 

Well, if that's the case then what would you recommend?

Should I add another AA battery to get 3V, step it up to 5V to run the logic and then step it down to 1.5 to drive the clocks original motor? Or is there logic that runs at 3V? should I forget about the clocks motor and replace that too? I'm just trying to rotate a piece of paper, pretty slowly, so I'm mostly worried about efficiency, not torque or speed. What is the most efficient low voltage, low speed motor/driver setup? DC motor, stepper motor?

What really drew me to this idea is the impressive battery life of these clocks, I thought even if I cut it in half or quarter it it would still be pretty good, but if I have to replace all the components, that's out the window.

Rotating a piece of paper requires a bit of torque. What is this piece of paper. Have you successfully tried with the clock motor?

A clock motor rotates at 1 RPM, 0.08 RPM or 0.007 RPM, depending if you drive from the seconds, minutes or hours shaft.

Do you know how to program? You could code any speed you want on a stepper motor. I’d use the Arduino Nano or an ATTiny

CMOS logic gates can run from 3-15 volts. Like the CD4xxx series; there are others.

Model Railroading uses fast clocks for enhanced operation. Here is an article that uses a 555 circuit and two batteries. Perhaps it could give you some ideas.

 

Why do you say that? There are many MCU's that will function on that supply voltage. As an example, many members of the TI MSP430 family.

I wasn’t aware of any. But that’s good!

 

1.5 volts? No, an AA alkaline battery is 1.5 volts new, but end of power is 1.0 to 0.9 volts. So you need a circuit
which can run down to there...

Or perhaps not. I have a wall clock and tried to run it of off 1 AA NiMH battery which is about 1.25 volts and it
sometimes stopped. Investigating I found it really needed about 1.4 volts to run reliability. My kludge
uses 2 eneloop AA NiMH in series and an emitter follower to drop the voltage to about 1.5 volts.

PS: I don't trust AA alkalines, too many leak these days, sometimes unused in the new packaging....

 

Well, I might have answered my own question. Did some searching around on Mouser ( they have a really nice search and filter tool) and I found the Texas Instruments TLC552CN. It's basically a dual 555 timer with a minimum supply voltage of 1V and low power draw. Now I just need to research and come up with the circuit to make it do what I want. There's a lot of info out there on 555 timers, so I'm hopeful I can figure it out, but if anyone has recommendations I'm all ears.
Since this is a consistent pattern, I probably don't even need two independent timers, and could use the TI TLC551CP, with some kind of a flip flop to make the two alternating outputs.

 

One flip flop is all that would be needed. I’d use a CD4013 wired as a toggle flip flop. It has two outputs: one of which is the negation/ opposite of the other.

 

One flip flop is all that would be needed. I’d use a CD4013 wired as a toggle flip flop. It has two outputs: one of which is the negation/ opposite of the other.

I'm trying to learn what flip flops are, it sounds like one side will always be high and the other side low. But for my circuit I only want very short pulses to the motor, and most of the time both outputs should be low, so I'm not sure if a flip flop is the right thing to use?

 

Well, I might have answered my own question. Did some searching around on Mouser ( they have a really nice search and filter tool) and I found the Texas Instruments TLC552CN. It's basically a dual 555 timer with a minimum supply voltage of 1V and low power draw. Now I just need to research and come up with the circuit to make it do what I want. There's a lot of info out there on 555 timers, so I'm hopeful I can figure it out, but if anyone has recommendations I'm all ears.
Since this is a consistent pattern, I probably don't even need two independent timers, and could use the TI TLC551CP, with some kind of a flip flop to make the two alternating outputs.

One thing you need to get a handle on is how critical the shape and duration of the pulse that goes to the clock motor is. For instance, would the clock function properly if, instead of a short pulse every second, it received a 50% duty cycle waveform with a 1 Hz frequency? If so, then life becomes much simpler. If not, then you need to determine the minimum and maximum pulse widths that will result in a reliable one-second advancement of the clock. Depending on what that turns out to be, a 55-based solution might be more than adequate, though if you are thinking ahead to keeping cost and manufacturability down when you start to make "many" of these (for what ever value constitutes "many" in your case), then an MCU-based solution has a lot of attractions and will likely result in the lowest-power solution. But there's nothing that says that the initial prototype can't be 555-based and then the improved "production" model can't be MCU-based.

 

One thing you need to get a handle on is how critical the shape and duration of the pulse that goes to the clock motor is. For instance, would the clock function properly if, instead of a short pulse every second, it received a 50% duty cycle waveform with a 1 Hz frequency? If so, then life becomes much simpler. If not, then you need to determine the minimum and maximum pulse widths that will result in a reliable one-second advancement of the clock. Depending on what that turns out to be, a 55-based solution might be more than adequate, though if you are thinking ahead to keeping cost and manufacturability down when you start to make "many" of these (for what ever value constitutes "many" in your case), then an MCU-based solution has a lot of attractions and will likely result in the lowest-power solution. But there's nothing that says that the initial prototype can't be 555-based and then the improved "production" model can't be MCU-based.

So I haven't done any experimenting because I don't have any kind of signal generator yet, but all that's happening with this clock motor is alternating the polarity of an electromagnet causing a simple magnet with a gear attached to rotate 180 degree's, and that gear drives another gear into 1/60 of 360 degrees. So I don't think the pulse width matters for the clock to function, but having 50% duty cycle would use a lot more power and drain the battery faster, and I want to keep the battery life as long as possible. Now how much difference in battery life it would make, I have no idea, probably worth experimenting.

I'm still trying to figure out if I need the dual timer 555 or if I could get a single timer 555 and somehow split the pulses into two alternating outputs?

I was thinking that the 555 timer would the lowest power consumption option, and cheaper. The mouser page for the TLC552CN shows the operating supply current as 340 micro amps, google shows the arduino nano power consumption of 19 milli amps.

If the initial prototype works well I'm thinking I would make 10 of them.

 

Hello, I have a, lets call it an art project, I want to make. I have some electronics experience, but no circuit design experience. What I want to do seems so simple, but I'm not sure the best way to do it.

Essentially I want to take a cheap quartz clock mechanism and make the seconds hand tick more frequently, maybe 2 or 3 or 4hz (I would go faster but I want to keep the battery life decent). I'm not making a clock, so accuracy is not important.

I already have the clock I want to modify, it's a ticking style, not the smooth motion style clock, and runs off of a single AA battery. I poked around at the circuit and I can see that the IC has two outputs for the two sides of the motor and they pulse alternately to 1.5 volts at .5hz. The pulse width is very small, looks like a spike.

I've thought I could change the crystal, change the IC, or create a new circuit. I doubt I could find a crystal for my desired effect, and I'm not good at shopping for IC's, so I'm leaning toward building my own circuit, or having someone tell me what IC to use. As I'm researching circuit design I'm seeing a lot of stuff with 555 timers and things that require 5 volts. I would really like to use the clock in its original form, so that means having everything run off of 1.5 volts. Also, cost is a factor, if the first one works out I'd like to make multiples at a reasonable price.

Any recommendations on how I should proceed?

CMOS 555 can run at 1.5V so this would be your best option. Far too difficult to use a microprocessor unless you have experience with coding.

 

If the TS can determine the frequency of the crystal, the simple change will be an external oscillator module at a higher frequency. four terminals power,common, and output. Get one that runs on 3.3 volts and add a second battery in series just for the oscillator module. A series resistor to avoid over driving the oscillator circuit and the fast clock is running.

 

I'm trying to learn what flip flops are, it sounds like one side will always be high and the other side low. But for my circuit I only want very short pulses to the motor, and most of the time both outputs should be low, so I'm not sure if a flip flop is the right thing to use?

Right… in that case a flip flop as I commented on won’t work. Sorry.

 

So I haven't done any experimenting because I don't have any kind of signal generator yet, but all that's happening with this clock motor is alternating the polarity of an electromagnet causing a simple magnet with a gear attached to rotate 180 degree's, and that gear drives another gear into 1/60 of 360 degrees. So I don't think the pulse width matters for the clock to function, but having 50% duty cycle would use a lot more power and drain the battery faster, and I want to keep the battery life as long as possible. Now how much difference in battery life it would make, I have no idea, probably worth experimenting.

I'm still trying to figure out if I need the dual timer 555 or if I could get a single timer 555 and somehow split the pulses into two alternating outputs?

I was thinking that the 555 timer would the lowest power consumption option, and cheaper. The mouser page for the TLC552CN shows the operating supply current as 340 micro amps, google shows the arduino nano power consumption of 19 milli amps.

If the initial prototype works well I'm thinking I would make 10 of them.

That's the supply current for the IC -- you also have to take into account the current for the external components.

The output of a 555 can have pretty low duty cycles. I don't know off the top of my head what the lowest practical duty cycle is, as it's been a long time since I've worked with them. The data sheet might give some indication of the limits.

 

Coupling a square wave to the coil via a capacitor will create a positive pulse on the leading edge and a negative pulse on the trailing edge. The value of the capacitor controls the width of the pulse. You might be able to make that work. I think it would be easier with excess voltage, so, maybe power it with 3V.

 

A CD4060 using a 32Khz Xtal will give you 2Hz upwards, but it needs a 4.5V supply..

 

A CD4060 using a 32Khz Xtal will give you 2Hz upwards, but it needs a 4.5V supply..

A 74HC4060 will run at 2 volts!