Can someone please help! - 12v timer switches

[Ste663]

Les, this is the pump I'm using for testing my concept.

**broken link removed**

 

[Les Jones]

That is a centrifugal pump so it can't be reversed. When the pump is stopped there will be very little restriction to the airflow so you could add another pump. You would connect the input of the original pump to the input of the extra pump. The extra pump would be powered when the valve was being driven to the open position by timer 3. I think these pumps take between 5 and 10 amps so you need to check the current rating of the relays on the timers.

 

[Ste663]

That's a great idea Les. I will get on ordered ASAP..thank you

 

[Ste663]

Morning Les. So with your alternative solution I don't need any diodes?

 

[Les Jones]

Not with your existing configuration with one pump. If you add the second pump you would still need one diode on the NC relay connection of timer 3. If the diodes arrive early then there is less work in adding them as all you would have to do is remove the wires from the NC connections of timers 2 & 3 an connect a diode. (Neither solution has an advantage over the other.) It would be interesting to know if the valve continues to take current when it has reached its position but as you have no test equipment you have no way to confirm this. I know that some mains voltage valves used on central heating just leave the motors stalled at the end of travel.

Les.

 

[Ste663]

It works! Thanks for your help Les. Just got one last problem - is there a way of powering them all (1,2,3 timers) at the same time and then using the 'ch1' on the timers to start the cycle? and, if so, is there a way of once the cycles been pressed it has to complete it's cycle before you can select (inflate or deflate) another cycle?

 

[Les Jones]

Do you have any more information on the modes of operation of the timer than that given on the ebay advert ? Wiring it up in the second way I suggested may allow you to interrupt the sequence. I will have to think carefully about how to deal with the situation if you interrupt the the sequence when the valve is part way through its travel.
Les.

 

[Ste663]

The instructions are on the bottom of this page - **broken link removed**

Thanks Les.

 

[Les Jones]

I miss read your message #26 I thought you wanted to be able to interrupt the sequence rather than prevent interruption of the sequence. Are you still planning to use the three position switch or change to push buttons ? The wording about the modes of operation are not clear enough for me to understand exactly how it behaves in each mode. We need a mode where the relay is actuated when the CH1 signal goes from low to high and stays high until the end of the delay setting. We also need to know what happens to the relay if the CH1 signal goes low again before the end of the delay time. The whole project would be much easier to do using a micro controller (a PIC chip or Atmel AVR device) if you can write simple programs in assembly language. If you are more into programming in "C" an Arduino board would be a good solution. Why do you want to use the CH1 input rather than initiate the timing by applying power to the timers. If we used two relays which were each energised initially by a push button then held on until the end of the timer output we could use a normally closed contact on the relay in series with the other push button to disable it until the end of the timing sequence. When you say it works which solution are you referring to, the diodes or re wiring the switch ?

 

[Les Jones]

I think this circuit should do what you want.

You will need 2 double pole double throw relays with 12 volt coils and contacts with a current rating suitable for the current drawn by the pumps. (Only one pump will be running at a time.) You may need the timer functions setting to function 1 for timer 1 and function 2 for timers 2 & 3
Les.

 

[Les Jones]

I think there may be a problem with the above diagram. Can you post the T1, T2 and N setting for all 3 timers and which colour wire closes and which colour wire opens the valve in your original diagram. (Just for reference of others following this thread I have been told that timer 1 is set to function 8 and timers 2 & 3 set to function 7 there is also a better explanation of the way these timers work in this youtube https://youtu.be/qfvSTyVYUqs )

 

[Les Jones]

Here are two possible solutions that seem to fit the requirements. (If my understanding is correct which it may not be as I do not understand the choice of timer functions 7 & 8)
This uses the original trigger method of applying power to the timers. All timers set to function 1
D3 and D4 could be omitted if the push buttons can handle the current taken by the pumps.

This uses the CH1 input to trigger the timers. All timers set to function 9

After designing these two circuits I realised that there is a small problem (With both circuits.) If the inflate button is pressed after timer 2 has timed out and before timer 1 has timed out timer 2 would be re triggered. This could be eliminated with a small relay activated by timer 1 with a set of contacts (NC) in series with the inflate button.

Les.

 

[Ste663]

Hi Les, sorry for the late reply but I've been away all weekend..thanks again for all your help. Here's the info you requested and I've taken a pic of the set up if this helps any -
Timer 1 - T1 10seconds - T2 1second - nx setting 1
Timer 2 - T1 0.1 seconds - T2 7 seconds - nx setting 1
Timer 3 - T1 0.1 seconds - T2 9 seconds - nx setting 1

 

[Les Jones]

After looking at the small problem I described in post 32 I realised that it would only occur in the version that uses the CH1 inputs. (The second diagram.) Will either of these solutions do or do you need it to works with the current way the timers are set ?

 

[mbarazeen]

if you have soldering skill, the entire functions can be done using a 1s time base or only one timer and some other electronics.

 

[Ste663]

I'm sure that will be perfect Les. I'll try it in the next couple of days and report back...are the switches I need classed as 'momentary switches'?

 

[Les Jones]

Yes.

 

[Ste663]

Sorry Les but I've just read post 34 again - will the timers still open and close as they do now?

 

[Les Jones]

The way timer 1 is configured for function 8 does not fit in with my understanding of how the inflate function should work. (this is from your original diagram.) This is the sequence of events as I understood them. You set the switch to inflate. Timer 1 starts its timing of about 11 second and sets the NO contact high which starts the pump. timer 2 also starts is timing and drives the valve into the open position which causes the item to be inflated. Timer 2 then switches off causing the valve to close. Timer 2 continues to drive the pump for another few seconds until the vale is closed. (So the air can not escape through the valve before it is fully closed. The way timer 1 is configured when you set the switch to inflate there is a 10 second delay and then the pump starts and runs for 1 second. If T1 and T2 were the other way round it would make sense as it would not matter if the pump delayed starting for 1 second while the valve opened. This all assumes that the timer in the Youtube is exactly the same as yours. If you do need the 10 second delay before the pump starts then neither of the two diagrams in post 32 will work as they rely on the NO contact on timer 1 to close almost as soon as the inflate button is pressed so that power is supplied to the timer (Via the NO contact.) until it switches back to the NC contact. The 0.1 second delay on timer 3 would just mean that the deflate button would have to be pressed for at least 0.1 of a second. (It would probably be pressed for longer than that anyway.) Have another look at the Youtube description of function 8 to see if it ties up with the way your timer behaves.