4 x manual set timer for pump control

[Cribey]

Hi All,

Total Newb here in respects, but have soldered boards before and have an extremely basic understanding of electronics.

I am would like to design a pump timer with 4 separate settable pot timers;

• 1 timer On for X seconds
• 1 timer On for Y seconds
• 1 timer On for A seconds
• 1 timer On for B second
  
• 1 purge button (pump on until I take my finger off the button)

All timers are to power ON the same 12VDC (0.3A Max) pump for a set (by trimpot) amount of time. The setting of time I will change using a trimpot for each, from 0-20 seconds.

I also want to be able to adjust the speed of the motor as well. PWM??

I am having trouble deciding what the best approach is to this. I want it to be super simple and not use Arduino. I am thinking 555 timers, trimpots, resistors, a few relays and caps.

Can someone please let me know what they think is the best solution to this? I want to be able to purchase all the components and solder it together myself.

Can I buy 4 of these (https://www.ebay.com.au/itm/1PC-12-...155802?hash=item3aab300b9a:g:uFoAAOSw~OdVbI52), plus a PWM and a on/off swith all connected to the pump?
Will this not work???

Thanks

 

[spec]

Hy Criby,

Welcome to ETO. I see you are from Oz: care to put your location in your user window on the left of your posts. It helps us to know you location so we can establish your mains voltage and component accessibility.

To answer your question: if I have correctly interpreted your requirements, yes, what you want can be done fairly simply.

On an initial evaluation, I would think it best to use a PMOSFET to switch the pump on and off and, as you suggest, use pulse width modulation to control pump motor speed.

One 555 timer could be used to control pump duration and another 555 timer could be used to control pump speed.

To set the pump duration a four-way rotary switch would be used and to control the pump speed a rotary potentiometer would be used.

Manually turning the pump on would be done with a simple push button switch.

Here are some questions:

(1) Is there just one pump?

(2) What starts the pump operating?

I would do you an outline circuit for discussion right now but I am a bit busy at the moment, but you are bound to get some advice from other ETO members too.

I may be able to post a circuit in eight hours-time.

spec

 

[Cribey]

Hi spec. Many thanks for your detailed reply - very much appreciated.
I've gone ahead and updated my profile to include my location. Good suggestion -yes in Australia, Melbourne.

Thanks for your answer to my questions. Great help.

I would like to press a switch (and release) and the pump is activated for X seconds. Press a second switch (and release) and the pump is active for Y seconds. Press another switch (and release) and the pump is active for A seconds. Press another switch (and release) and the pump is active for B seconds. Press another switch and the pump is active until I release the switch.
I would also like to control the speed of the pump, I think with a PWM is best.

Can I purchase a timer circuit to run (as programmed by a trimpot) for 0-20 seconds? I will purchase 4 of these, some switches and a PWM to run the circuit.

Thoughts? Links? Ideas? Advice?

Thanks in advance

 

[ChrisP58]

Welcome to ETO Cribey.

A few questions to make sure you get what you want.

Do you want the timers retrigerable? That means, will the time period restart if the button is pushed before the end of the cycle. Example. if button X is pushed once to start a 20 seconds cycle, but is pushed again at 15 seconds, do you want the pump to run for 20 seconds or 35 seconds?

Do the timers need to be interlocked? Meaning, if one timer is already running, it will prevent another timer from starting and extending the pump run time.

 

[Cribey]

Do I want a SINGLE SHOT One Shot Momentary Interval circuit?

Or

Power-ON Open delay Relay Timer Delay Switch Circuit Module?

Or something entirely different??

 

[Cribey]

Hello ChrisP58 . Sorry I didn't see your message come through before I posted again.

I would like a press of the timer button to be non-retriggerable. So the same and other buttons don't trigger another timed event. One press, one event, everything else is locked out until the timer ends.
If this is too complex to achieve, then I can live without it as the other buttons won't be pressed when one of the timer buttons are pressed/triggered.
I could haves 4 separate timers hooked up to the one pump if that's the easy solution??? With a PWM of course.

Thanks!!

 

[spec]

Hi spec. Many thanks for your detailed reply - very much appreciated.
I've gone ahead and updated my profile to include my location. Good suggestion -yes in Australia, Melbourne.

Thanks for your answer to my questions. Great help.

I would like to press a switch (and release) and the pump is activated for X seconds. Press a second switch (and release) and the pump is active for Y seconds. Press another switch (and release) and the pump is active for A seconds. Press another switch (and release) and the pump is active for B seconds. Press another switch and the pump is active until I release the switch.
I would also like to control the speed of the pump, I think with a PWM is best.

Can I purchase a timer circuit to run (as programmed by a trimpot) for 0-20 seconds? I will purchase 4 of these, some switches and a PWM to run the circuit.

Thoughts? Links? Ideas? Advice?

Thanks in advance

Hy Criby,

Thanks for putting your location in your user window and for further information on your pump control system.

Four timer modules with initiating push buttons for for each pump duration would be relatively straight- forward using the timer modules that you describe which use a relay to switch the pump motor. The problem is that a relay would not really be ideal for PWM speed control, but a MOSFET would be ideal.

I will give your requirements some thought.

spec

 

[Cribey]

Hi spec , many thanks for your reply.

This is the pump I have ordered and would like to control: https://www.ebay.com.au/itm/2619703...ad2e1e9bda6&bu=43046401518&cp=1&sojTags=bu=bu

So which circuit would suit what I am trying to acheive?
Single-shot (monostable) or Power-ON Open delay MOSFET Timer Delay Switch Circuit Module

Looking forward to hearing your thoughts on this spec. Really looking forward to ordering the circuits/parts and getting it all hooked up.

Cheers.

 

[spec]

Hy again Criby,

Here is an outline schematic to indicate the topology and complexity of the circuit that I suggest for your pump controller. Note that the circuit has not been analyzed in detail or optimized. It may even have gross errors but that does not matter at this stage. I will sort all that if you are interested in this approach.

spec

Obsolete: see schematic in post #17

 

[spec]

Hi spec , many thanks for your reply.

This is the pump I have ordered and would like to control: https://www.ebay.com.au/itm/2619703...ad2e1e9bda6&bu=43046401518&cp=1&sojTags=bu=bu

So which circuit would suit what I am trying to acheive?
Single-shot (monostable) or Power-ON Open delay MOSFET Timer Delay Switch Circuit Module

Looking forward to hearing your thoughts on this spec. Really looking forward to ordering the circuits/parts and getting it all hooked up.

Cheers.

No sweat Cribey. Our posts crossed.

spec

 

[Les Jones]

Hi spec,
I don't think the timer modules linked to in post #1 will work in your circuit. I am assuming the 3 connetor terminal strip is the relay change over contacts and the 2 connector terminal strip is the power to the timer. (It does not seem to have a trigger input.) Also the data on the timer does not make it clear if the relay actuates when power is applied and switches off after the time period or if the relay actuates after a time delay then stays on. Also Cribey wants an interlock so that buttons do not opperate during the time period. If you can get timers as drawn in your circuit the power to the push buttons could be via a pull up resistor. If you added another 4 input diode OR gate to the timer outputs with its output connected to the bottom of the pull up resistor then tis would disable the buttons during the time period.

Les.

 

[spec]

Hi spec,
I don't think the timer modules linked to in post #1 will work in your circuit. I am assuming the 3 connetor terminal strip is the relay change over contacts and the 2 connector terminal strip is the power to the timer. (It does not seem to have a trigger input.) Also the data on the timer does not make it clear if the relay actuates when power is applied and switches off after the time period or if the relay actuates after a time delay then stays on. Also Cribey wants an interlock so that buttons do not opperate during the time period. If you can get timers as drawn in your circuit the power to the push buttons could be via a pull up resistor. If you added another 4 input diode OR gate to the timer outputs with its output connected to the bottom of the pull up resistor then tis would disable the buttons during the time period.

Les.

Hy Les,

I always appreciate your helpful suggestions. All that you say is quite right, but as I said, the circuit posted in only an outline to show the scope and principle.

I also agree about the trigger inhibit when a timer is active, but thought it best to leave it out for a concept type circuit.

If the OP is interested in this approach I will do a more thorough and detailed design.

By the way, does the PWM look OK to you?

spec

 

[Les Jones]

Hi spec,
The PWM circuit looks OK. I was just going to suggest using an LM317 variable regulator to control the motor speed as it only consumes 0.3 amps. It would not matter that the minimum output would be 1.25 volts as the motor probably will not run on less than about 3 volts. I have recently bought **broken link removed** which is similar ad it needs about 4.5 volts for it to start. Interestingly it is just a normal brush motor not an electronic commutated one as stated in the advert. The one I received also has the brushes fitted rotated by 90 degrees. (The curvature on the end of the prushes is at right angles to the axis of the commutator.) Also it is not a gear pump. It is a variation on a swash plate pump but uses silicon rubber bulbs (5) instead of pistons and cylinders.

Les.

 

[Cribey]

This is way over my head. I can purchase components and follow a design (pretty much) to solder together on a breadboard. Or I can purchase circuits that you reccommend and put them together as required too.

Thank you so much spec and Les Jones. Truly remarkable...

I don't mind if the buttons don't have an interlock, as I wont be pushing other buttons once a button has been pushed.

I'm interested to move forward with whatever you guys reccommend

So so grateful. Thank you.

 

[spec]

Hi spec,
The PWM circuit looks OK. I was just going to suggest using an LM317 variable regulator to control the motor speed as it only consumes 0.3 amps. It would not matter that the minimum output would be 1.25 volts as the motor probably will not run on less than about 3 volts. I have recently bought **broken link removed** which is similar ad it needs about 4.5 volts for it to start. Interestingly it is just a normal brush motor not an electronic commutated one as stated in the advert. The one I received also has the brushes fitted rotated by 90 degrees. (The curvature on the end of the prushes is at right angles to the axis of the commutator.) Also it is not a gear pump. It is a variation on a swash plate pump but uses silicon rubber bulbs (5) instead of pistons and cylinders.

Les.

Hi Les,

Thanks for giving the PWM a once over.

Like I have said before, you are a clever fellow; using a voltage regulator would be a much simpler approach.

Also thanks for the pump link.

spec

 

[spec]

This is way over my head. I can purchase components and follow a design (pretty much) to solder together on a breadboard. Or I can purchase circuits that you reccommend and put them together as required too.

Thank you so much spec and Les Jones. Truly remarkable...

I don't mind if the buttons don't have an interlock, as I wont be pushing other buttons once a button has been pushed.

I'm interested to move forward with whatever you guys reccommend

So so grateful. Thank you.

OK Cribey,

Don't worry we will sort out a good circuit for you.

spec

 

[spec]

Hy again Cribey,

Here is a more complete circuit:

spec

Issue 3 of 2016_08_02

​

NOTES
(1) Hopefully this circuit, takes into account Les' comments about the functioning of the timer modules.
(2) The circuit has lock out
(3) The legend inside the timer module symbols got lost when going from a schematic to png image. Starting at the top and going clockwise the pins are: 12V, NO, W, NC, 0V.
(4) The PMOSFET is not defined. Many PMOSFETs will do this job. I will define a PMOSFET.
(5) All capacitors are through hole (not surface mount), ceramic X7R dialectic +- 10% or better 16V min working voltage except C1 which is polypropylene or polyester +-10% or better, 16V minimum
(6) Change R19 to 470R
(7) Change Q3 t0 BC337
(8) Change Q4 to BC337
(9) Fit a 100R resistor between Q4 collector and N1 pin 2

 

[spec]

Hy Les,

I have just been looking at using an LM317 to control the pump motor speed. Unfortunately the drop out voltage, from the data sheet is 3V which means that worst case the pump motor may only see 9V max sp perhaps stay with the PWM approach. Of course a Low Drop Out (LDO) regulator would solve that problem.

Just thinking out loud, but wouldn't PWM be better for starting a motor at low power as it gives the motor a 'kick', providing the PWM frequency is a low enough that is. I have chosen a nominal frequency of 10Hz.

spec

 

[spec]

Hy again Cribey

Here is another version of the pump controller. This one is simpler because it embodies Les' method of pump speed control, only using a low drop out (LDO) voltage regulator.

spec

Obsolete: see post #23 of 2016_08_02

 

[Les Jones]

Hi spec,
You make a valid point about the high dropout voltage of the LM317. I did not think about the voltage drop so Your PWM solution is much better than my suggestion. I don't know of any variable LDO regulators and even an LDO regulator would have some volt drop. I think your new circuit (Post #17) should work using the timer modules linked to in post #1 providing the relay is energised when power is applied and de energise after the delay period. (I think this will be the way they work.) The way you have connected the override button (S5) would run the motor at full speed when pressed. If Cribey wants the speed control to function with the override button then you could add a fifth diode to the diode OR gate and connect the push button between +12 and the anode of the diode. Another way would be to connect the override button between emitter and collector of Q3. I don't know if PWM would be better than a variable voltage source at starting the motor at low speed settings.

Edit.
spec I see you have found a variable LDO regulator wet a dropout voltage that may be good enough for Cribey's application. (It would be interesing to now what it was being used for.)

Edit 2
I've just been looking at your circuit in post #19. The way you have Q2 shorting out the speed control pot would mean that the regulator would still be outputting 1.25 volts when the speed post was shorted. It would probably be better to use the enable pin to shut down the regulator output.

Les.