This sounds like the most elegant and simplest solution. What do you mean when you say 'The limit switch would be capacitively coupled to the 4060 RST pin', what does 'capacitively coupled' mean?
Connect it via a small capacitor, so it just gives a short pulse, when the switch is made. The reset pin will still need a pull-down resistor and so will the switch.
Its got to be capable of driving out of the limit, and shouldn't consume any power at the limit position. Therefore use a NC limit switch to ground with a pullup resistor. When it reaches either half-turn position, a peg on the mechanism operates the switch, so its output goes high and it no longer draws current. Use a pulldown resistor on RST at least 20x the switch pullup value + a Schotty clamping diode, anode to Gnd to stop RST going negative when the switch recloses. It will probably also need a small capacitor across the switch to prevent contact bounce when the switch recloses resetting the timer and stopping the motor for another 15 minutes, and 47 ohms directly in series with the switch to limit the capacitor transient discharge current to under 100mA!
Another approach that may be easier to implement is to use a SPST limit switch to connect either a delayed Qn, or a pulldown to RST. The delay (which could be as simple as series R, C to ground) provides time for the motor to drive out of the limit position before the limit reset circuit is reactivated, so contact bounce on opening doesn't re-reset it.
Well if I were to do it I would use the programmable controller which I have available to me. But I do understand such an approach is quite expensive if you have to buy the components. I am thinking of using a thru beam photoelectric sensor which looks thru the hour glass. The sand would block the sensor and the motor doesn't run. When the it's empty the motor will rung and turn the hour glass around until the full part block the sensor again then the motor stop. That way I use the hour glass itself as the timing device.
I like the stepper motor approach. There is no need for limit switches, just count steps. Whether the forward-reverse approach or forward-forward wouldn't matter.
Since the stepper approach, with no limit switch, requires counting, a uC is just about required.
Have we settled on a torque requirement?
https://www.pololu.com/category/120/stepper-motor-drivers
I've put together a quick LTspice sim of my reply #27 suggestion, using a behavioral model of the 4060's RST and Qn pin timings, showing its immune to vicious switch bounce.
Its got a few extra parts - a BAT54S dual series Schottky diode, a 10K resistor and a 1nF capacitor for RST input ESD protection, and also to terminate the RST pulse cleanly when Qn goes low. I've also shown how junkbox BJTs could be used to drive the O.P's motor, though it would be much simpler to drive a low Vgs threshold MOSFET direct from the 4060, with only a 1K series gate resistor to limit the transient 4060 output current.
I've put together a quick LTspice sim of my reply #27 suggestion, using a behavioral model of the 4060's RST and Qn pin timings, showing its immune to vicious switch bounce.
Its got a few extra parts - a BAT54S dual series Schottky diode, a 10K resistor and a 1nF capacitor for RST input ESD protection, and also to terminate the RST pulse cleanly when Qn goes low. I've also shown how junkbox BJTs could be used to drive the O.P's motor, though it would be much simpler to drive a low Vgs threshold MOSFET direct from the 4060, with only a 1K series gate resistor to limit the transient 4060 output current.
Woow, this is great Ian! I opened the sim but honestly the details are above my understanding.
I understand the schematic in general, and I think i could build it since I have most of the parts:
-BAT54S dual series Schottky diode: in only have zenner diodes, 1N4001, 1N4148, 1N914 and Germanium diodes
-found an appropriate NC/NO switch (can operate as both) (
https://kagi.com/proxy/12-Pieces-Red-Button-Metal-Long-Lever-Arm-Micro-Limit-Switch-Home-LOT.jpg?c=D7u0yXs99oGy9xkm-57YOw_yiy23Lp8lOir26GxuiRppPXbbcSMFyMxCHS_RT3nDYW4553c2Q7MyVHuV0-2bAIakCIPW-Xc8XLcQblY92hD_f0dmwI47OvHF0ZzW3w5g1iTl2cd8gLXtWr0XNNA6TDuW1M5MtaWnH20xutvHjm2P3A4bUwWCJnEyGMExgyD7Can I use only half of the SPDT switch from the schematic, and use a NC switch connected to Gnd?
Would the circuit be simplified if i'd replace the transistors with 1 MOSFET? I have IRFZ44N (N-channel, Vgs threshold 2-4 (min-max)) and IRF540N (N-channel, Vgs threshold 2-4 (min-max))
As you don't have Schottky diodes for the input clamping, use 2x 1N4148, but add an extra 10K resistor between the junction of the two diodes and the RST input pin.
Although the switch was drawn in the sim as two individual NO and NC halves (because LTspice doesn't come with a SPDT switch component), in real life it *MUST* be a single break-before-make SPDT switch (or one pole of a DPDT switch), so there is absolutely no possibility of both sides being on at the same time, even momentarily. If it did it would short the charged capacitor, damaging the switch and loosing the RST pulse. You've found a suitable SPDT switch, so just use it, COM towards the RST pin.
If you are unlucky, 4V is too high a threshold voltage, as there isn't much margin between that and the lower limit of your nom. 5V supply voltage, so the MOSFET channel may not enhance enough to pass the motor current. However, odds are its quite a bit lower, so its worth trying the IRFZ44N at 4.5V, source to ground, gate strapped to +4.5V, your motor between its drain and +4.5V, and check the voltage drop drain to source across the MOSFET. It should be under 0.1V with the motor running normally, which means you can use that MOSFET. If its higher, switch off immediately, before the MOSFET overheats.
I like the stepper motor approach. There is no need for limit switches, just count steps. Whether the forward-reverse approach or forward-forward wouldn't matter.
Since the stepper approach, with no limit switch, requires counting, a uC is just about required.
Have we settled on a torque requirement?
https://www.pololu.com/category/120/stepper-motor-drivers
How do you know the motor's position when it's powered on? There are no limits so it's not as though it can be driven to a stop.
I agree about using a microcontroller. I'd use the old PIC12F509, purely because I have a load in stock.
I've put together a quick LTspice sim of my reply #27 suggestion, using a behavioral model of the 4060's RST and Qn pin timings, showing its immune to vicious switch bounce.
Its got a few extra parts - a BAT54S dual series Schottky diode, a 10K resistor and a 1nF capacitor for RST input ESD protection, and also to terminate the RST pulse cleanly when Qn goes low. I've also shown how junkbox BJTs could be used to drive the O.P's motor, though it would be much simpler to drive a low Vgs threshold MOSFET direct from the 4060, with only a 1K series gate resistor to limit the transient 4060 output current.
Very good, but the wait time is off by a factor of 60. Run the oscillator at 9.1Hz and use the Q14 output to for a half period of 15 minutes.
If there's ambiguity, add a line to the NC switch to make it's clear it's normally closed.
As you don't have Schottky diodes for the input clamping, use 2x 1N4148, but add an extra 10K resistor between the junction of the two diodes and the RST input pin.
Although the switch was drawn in the sim as two individual NO and NC halves (because LTspice doesn't come with a SPDT switch component), in real life it *MUST* be a single break-before-make SPDT switch (or one pole of a DPDT switch), so there is absolutely no possibility of both sides being on at the same time, even momentarily. If it did it would short the charged capacitor, damaging the switch and loosing the RST pulse. You've found a suitable SPDT switch, so just use it, COM towards the RST pin.
If you are unlucky, 4V is too high a threshold voltage, as there isn't much margin between that and the lower limit of your nom. 5V supply voltage, so the MOSFET channel may not enhance enough to pass the motor current. However, odds are its quite a bit lower, so its worth trying the IRFZ44N at 4.5V, source to ground, gate strapped to +4.5V, your motor between its drain and +4.5V, and check the voltage drop drain to source across the MOSFET. It should be under 0.1V with the motor running normally, which means you can use that MOSFET. If its higher, switch off immediately, before the MOSFET overheats.
Ian, I have followed your advice and modified the circuit. I created a model for the CD4060 with all the pins as they are laid out, but there are a few pins which I dont know where to connect.
See attached my very unprofessional LTSpice schematic. Please correct it and modify it accordingly to make a complete circuit. Thanks!
@Zero999,
Agreed on using a MCU - if you've got the toolchain ready to go a PIC12F509 makes as much sense as any. The XC8 compiler does a reasonable job of hiding the horrors of the Baseline PIC architecture, so you don't even have to suffer wrangling MPASM assembly code like we had to back in the 90's!
Yes, the wait time was off deliberately. If I'd done the sim with the real ratio between the wait time and the other timings, (and the real 4060 oscillator frequency and division ratio) the run-time would have gone through the roof due to LTspice calculating at least two timesteps per clock edge, and as I disabled waveform compression to permit zooming in on the switch bounce transients and the 'runt' RST pulse, the already ridiculous >21 MB .raw (results) file size would have bloated even further, possibly to the point of crashing the waveform viewer.
I *SHOULD* have drawn a SPDT switch symbol and created hierarchical schematics for the switch + associated control sources and the behavioral 4060 'lite', but that's starting to turn into a full project rather than a quick 'freebie' proof of concept. The switch bounce part of the simulation is something I've previously posted here and it literally took me under five minutes to grab it, delete the bits I didn't want and add a NC switch model.
@vranghel,
You *MUST* use a SPST SPDT changeover switch to trigger the RST circuit at the desired stopping point(s). A simple switch to Gnd as you have shown will *NOT* work at all - the motor wonts stop till the timer output pin goes low again after another 15 minutes!
Take the output from Q14 (pin 3) not pin 4. You'll also need two resistors and a capacitor, values chosen according to the formulae in the '4060 datasheet for aa frequency of 9.1Hz, connected to pins /CLK, Rext and Cext as per the RC oscillator circuit in the datasheet. That should give you the required 15 minute delay.
I would also recommend a 100nF decoupling capacitor across '4060 acroos pins 16 (Vdd) and 8 (Gnd), and a 1K resistor in series with the MOSFET gate.
@vranghel,
You *MUST* use a SPST changeover switch to trigger the RST circuit at the desired stopping point(s). A simple switch to Gnd as you have shown will *NOT* work at all - the motor wonts stop till the timer output pin goes low again after another 15 minutes!
Take the output from Q14 (pin 3) not pin 4. You'll also need two resistors and a capacitor, values chosen according to the formulae in the '4060 datasheet for aa frequency of 9.1Hz, connected to pins /CLK, Rext and Cext as per the RC oscillator circuit in the datasheet. That should give you the required 15 minute delay.
I would also recommend a 100nF decoupling capacitor across '4060 acroos pins 16 (Vdd) and 8 (Gnd), and a 1K resistor in series with the MOSFET gate.
@Ian
I have made the changes to the circuit you suggested.
I have used the resistors and capacitor values from here
https://www.gadgetronicx.com/how-to-build-24-hours-timer-circuit-cd4060/ and a variable resistor, and with output Q14, i should be able to adjust the timer from 8 min to 20 min.
However, I do not understand what do you mean about the switch: 'SPST changeover switch '
Are you saying that how the switch is wired in is incorrect, or that the type of switch i'm planning to use (
https://kagi.com/proxy/12-Pieces-Red-Button-Metal-Long-Lever-Arm-Micro-Limit-Switch-Home-LOT.jpg?c=D7u0yXs99oGy9xkm-57YOw_yiy23Lp8lOir26GxuiRppPXbbcSMFyMxCHS_RT3nDYW4553c2Q7MyVHuV0-2bAIakCIPW-Xc8XLcQblY92hD_f0dmwI47OvHF0ZzW3w5g1iTl2cd8gLXtWr0XNNA6TDuW1M5MtaWnH20xutvHjm2P3A4bUwWCJnEyGMExgyD7) is the wrong one, or both??
I'm sorry for all these questions, i'm a beginner.
I have attached the adjusted circuit.
+1 for relays to control the motor.
Probably one that flip polarity and one that is just simple on/off. (It's safer than the alternative way to do it, which could end up shorting the input by mistake)
Setup a 555 timer configured to toggle its output state every 15min.
If 555 output is low the direction relay is one way, if high it's the other way.
Then you just need to handle the limit switch cut-offs.
Use a 3rd relay to combine both limit switches into one pseudo switch that changes depending on 555 output / direction.
Now use that pseudo switch to control the motor on/off control relay.
When the 555 output changes it will change which limit switch is controlling the motor on/off relay and flip the motor direction at the same time.
The newly selected limit switch wont be tripped so it will start moving in that direction until it reaches it. etc..
In my head that sound like it should work.
3x relays and 1x 555 timer.
@vranghel,
You *MUST* use a SPST changeover switch to trigger the RST circuit at the desired stopping point(s). A simple switch to Gnd as you have shown will *NOT* work at all - the motor wonts stop till the timer output pin goes low again after another 15 minutes!
Take the output from Q14 (pin 3) not pin 4. You'll also need two resistors and a capacitor, values chosen according to the formulae in the '4060 datasheet for aa frequency of 9.1Hz, connected to pins /CLK, Rext and Cext as per the RC oscillator circuit in the datasheet. That should give you the required 15 minute delay.
I would also recommend a 100nF decoupling capacitor across '4060 acroos pins 16 (Vdd) and 8 (Gnd), and a 1K resistor in series with the MOSFET gate.
@Ian
I have made the changes to the circuit you suggested.
I have used the resistors and capacitor values from here https://www.gadgetronicx.com/how-to-build-24-hours-timer-circuit-cd4060/ and a variable resistor, and with output Q14, i should be able to adjust the timer from 8 min to 20 min.
However, I do not understand what do you mean about the switch: 'SPST changeover switch '
Are you saying that how the switch is wired in is incorrect, or that the type of switch i'm planning to use (https://kagi.com/proxy/12-Pieces-Red-Button-Metal-Long-Lever-Arm-Micro-Limit-Switch-Home-LOT.jpg?c=D7u0yXs99oGy9xkm-57YOw_yiy23Lp8lOir26GxuiRppPXbbcSMFyMxCHS_RT3nDYW4553c2Q7MyVHuV0-2bAIakCIPW-Xc8XLcQblY92hD_f0dmwI47OvHF0ZzW3w5g1iTl2cd8gLXtWr0XNNA6TDuW1M5MtaWnH20xutvHjm2P3A4bUwWCJnEyGMExgyD7) is the wrong one, or both??
I'm sorry for all these questions, i'm a beginner.
I have attached the adjusted circuit.
Just use a SPST switch: normally closed to 0V and normally open to +V.
I'd just use 620k for both timing resistors and 100nF for the capacitor. The capacitor needs to be non-polarised and 10µF is quite a big value for such a capacitor.
Here's a more detailed explanation of how the type of oscillator used in the 4060 works and how to calculate the component values. When the two resistor values are the same F = 0.559/(RC). If you really need to add a trimpot, reduce the value of the resistor going to pin 10 of the 4060 to 390k and put your 470k trimmer in series.
https://www.onsemi.com/pub/Collateral/AND9983-D.PDFPresumably this doesn't need to be accurate. If you need precision timing, the only sane way is with a microcontroller using a crystal for the clock. An RC oscillator won't be stable enough, even with a trimmer.
Sorry for the confusion: 'SP
ST changeover switch' was a typo, which should have been 'SP
DT changeover switch'.
To use your preferred switch, connect its NC pin to Gnd, NO pin to junction of R1+C1 in your "hourglass circuit.asc", and its C (com) pin to the left end of R2. Arrange two pegs on the mechanism to trip the switch, one for each hourglass orientation, that approach the switch from the hinge end of the lever actuator so they slide over it without catching on it.
R1+C1 provide a delay to allow the motor enough time to drive the peg off the switch actuator when the motor starts, before re-enabling the limit switch to RST circuit. Unless the speed is high enough that it coasts off the actuator, past the switch when it stops, Zero999's suggestion of simply switching Vcc to RST will *NOT* work. I looked at capacitively coupling it to allow the motor to restart, but it was difficult to avoid any switch bounce on opening resetting the 4060, and stopping the motor for an additional 15 minutes just after the switch open.
@PSI: Build your 50% duty cycle 15 minute 555 timer, then report back to us what type of capacitor you used, and how much off the ideal design RC values you had to go to compensate for leakage current!
Then see how temperature sensitive it is . . .
Sorry for the confusion: 'SPST changeover switch' was a typo, which should have been 'SPDT changeover switch'.
To use your preferred switch, connect its NC pin to Gnd, NO pin to junction of R1+C1 in your "hourglass circuit.asc", and its C (com) pin to the left end of R2. Arrange two pegs on the mechanism to trip the switch, one for each hourglass orientation, that approach the switch from the hinge end of the lever actuator so they slide over it without catching on it.
And silly me just copied it, without thinking.
@PSI: Build your 50% duty cycle 15 minute 555 timer, then report back to us what type of capacitor you used, and how much off the ideal design RC values you had to go to compensate for leakage current! Then see how temperature sensitive it is . . .
It's possible, but won't be anywhere near accurate. Use it in Schmitt trigger mode, with pin 5 tweaked to give several RC time constants.
If you need precision timing, the only sane way is with a microcontroller using a crystal for the clock
The 4060 has the option to use a crystal if you want accuracy.
If you need precision timing, the only sane way is with a microcontroller using a crystal for the clock
The 4060 has the option to use a crystal if you want accuracy.
But there's a limit to the range of crystal frequencies available and you'll need a butt load of ICs to get the desired delay. The 4521 is a better choice, having 24 stages, which would give a period of 512 seconds, with a 32768Hz crystal, but another IC would be required to get 15 minutes. A microcontroller is a more sensible approach.
Yes, we can't get there in one 4000 series chip as the 214 max division ratio isn't enough to get a 32768 HZ crystal down to the required 30 minute period (15 minutes on). The best it can do is 2 Hz on Q13. Even if you cascade it with another 4060 or 4020 you'll need to add logic to the first one to reset it early to 'bump' the 8 Hz Q11 output clocking the second counter up to the required 9.1 Hz. Unfortunately Q10 isn't available so the required terminal count of binary 1110 0001 0000 cant easily be implemented. If it was, it could be done by diode logic. The easiest workaround is to go to a 100Hz crystal, take the output from Q13 with a terminal count of 10 1010 1110 1000, for a clock that is 212 pm fast. Ideally it would be 10 1010 1110 1010, but again Q1 isn't available so we cant get it down to only 30 ppm fast. Seven diodes and a pullup resistor later, the first 4060 will be outputting very close to the correct frequency.
Of course a MCU is the sane choice as it facilitates the use of arbitrary integer division counts, allowing the final accuracy to be as good as the crystal.
Alternatively, go to an auto scrapyard and harvest a few windshield motors.
Add limiter switches in series with the motor, to turn it off after each half turn, then add a 15 minutes timer to override the limiters for a short while, just enough to start a new spin. Give it a steampunk look so it won't need a case to hide its internals.
But there's a limit to the range of crystal frequencies available
How times have changed,don't seem that long ago that for a reasonable amount of cash,you could get a crystal "grown" to whatever exotic frequency you required
But there's a limit to the range of crystal frequencies available
How times have changed,don't seem that long ago that for a reasonable amount of cash,you could get a crystal "grown" to whatever exotic frequency you required
I didn't know that. What was the lowest frequency you could get? For a period of 30 minutes and a 24 stage counter. F = 2
24/(60*30) ≅ 9320.676Hz, but I've not seen a crystal below 10kHz before and 20kHz is currently the lowest frequency I could find.
@PSI: Build your 50% duty cycle 15 minute 555 timer, then report back to us what type of capacitor you used, and how much off the ideal design RC values you had to go to compensate for leakage current! Then see how temperature sensitive it is . . .
It's possible, but won't be anywhere near accurate. Use it in Schmitt trigger mode, with pin 5 tweaked to give several RC time constants.
True, but does it really need to be that accurate, given the application?
I guess only the OP can decide.
Just use a SPST switch: normally closed to 0V and normally open to +V.
I'd just use 620k for both timing resistors and 100nF for the capacitor. The capacitor needs to be non-polarised and 10µF is quite a big value for such a capacitor.
Here's a more detailed explanation of how the type of oscillator used in the 4060 works and how to calculate the component values. When the two resistor values are the same F = 0.559/(RC). If you really need to add a trimpot, reduce the value of the resistor going to pin 10 of the 4060 to 390k and put your 470k trimmer in series.
https://www.onsemi.com/pub/Collateral/AND9983-D.PDF
Presumably this doesn't need to be accurate. If you need precision timing, the only sane way is with a microcontroller using a crystal for the clock. An RC oscillator won't be stable enough, even with a trimmer.
@Zero999
For the RC oscillator, using same timing resistors, 620k and 100 nF for the cap, i'd get a delay of 17 minutes (from pin 15 (Q10))
It doesnt need to be accurate at all. I have added the resistor and trimmer values you suggested in the schematic.
Sorry for the confusion: 'SPST changeover switch' was a typo, which should have been 'SPDT changeover switch'.
To use your preferred switch, connect its NC pin to Gnd, NO pin to junction of R1+C1 in your "hourglass circuit.asc", and its C (com) pin to the left end of R2. Arrange two pegs on the mechanism to trip the switch, one for each hourglass orientation, that approach the switch from the hinge end of the lever actuator so they slide over it without catching on it.
@Ian
Disregarding what the actual symbol looks like in the schematic, is the switch wired in correctly, if I will use the previously shown switch in NC mode? Since i will only be using 2 pins of the switch to achieve the NC operation, does it matter which way are those 2 poles placed in the circuit? I'd say no.
Does the overall circuit look ok?
Thanks!
Attached the circuit LTSpice and a pic of the circuit