4 x manual set timer for pump control

[spec]

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.

It was still a good idea and I have used your voltage regulator approach in a new version of the pump controller in post #19. Luckily I found a variable voltage very low drop out regulator (around 300mV) which should be fine.

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.)

Hmm, you have got me thinking now about how those timers 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.

Yes, I have done various circuits, some with speed controlled override, but but I figured that the purge function would be carried out at full pump speed.

Edit.
spec I see you have found a variable LDO regulator with a dropout voltage that may be good enough for Cribey's application.

It has a very low dropout voltage. It is a 3A part which is £1.40 from Digikey. There are also 1.5A (£1.67), 5A (£5.52), and 7.5A (£11.40) parts, but the IO differential is only 26V on the whole family.

(It would be interesting to now what it was being used for.)

I am always messing with power supplies and keep a library of spec sheets for interesting/useful parts- bit of an anorak really.

spec

 

[spec]

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.

Another good idea.

That will also allow a simpler gating arrangement- I think.

spec

 

[spec]

Hy Les

Issue 2 of pump controller version 3 with your suggested mod. This had greatly simplified the circuit and improved the performance.

spec

 

[Cribey]

Amazing work spec and Les Jones . Thank you both sao much for your time , support and input.

Can I purchase 4 of these: **broken link removed**

Hook them up in parallel, and add a button to those circuits to have the purge feature.

Then use this to control the pump speed: **broken link removed**

I don't want to take away from all your hard work, thought and commitment to my request. But will this approach work?

I'll wait until you both reply to move forward and take a direction on the build.

Thanks.

 

[spec]

Hy Cribey,

Good idea about using those modules. Why build when you can buy ready-made and for such a good price too.

I will give your approach some thought, but in principle I can't see a problem.

spec

 

[Cribey]

Any further thoughts on this??

Cheers

 

[Cribey]

Parts ordered. Excited for the build. Thanks for all your help and support!!

 

[Cribey]

Hi All,

I finally made the build but am having problem getting the motor pump to run.

I purchased:

• 4 x thse timers: **broken link removed**
  
• 1 x this pump: https://www.gearbest.com/other-consumer-electronics/pp_399925.html

I am using the DC power source that came with the pump (9V, 1A), and the lights and timers click on and go off, but I cannot get the pump to turn on.

When I connect the power source directly to the pump it does work.

I have tried all possible combinations with the outputs to the pump from the relay.

Any thoughts?

 

[spec]

Hi Cribey,

Nice to hear from you.

Good choice of timer modules from what I can tell from the eBay advert; I haven't seen Micro Controller Unit (MCU) based timers before. Which actual timer modules did you buy?

In your picture I can only see two wires going from the motor to the timer relay output and my initial thought is that:

(1) The the power supply 9V should be connected to the Wiper (W) of the relay (looks like the center terminal).

(2) The black motor wire should be connected to the 0V of the 9V Power Supply Unit (PSU)

(3) The red motor wire should be connected to the relay Normally Open (NO) terminal (looks like the right terminal on your picture). Or, possibly, the relay Normally Closed (NC) terminal, depending on how the timer works.

Hopefully, you should then get the pump to run.

spec

 

[spec]

You should really connect two IN400x (where x is any number) rectifier diodes to the motor to protect the relay contacts:
(1) Diode 1: cathode to motor red wire. Anode to motor black wire
(2) Diode 2: anode to motor red wire. Cathode to PSU 9V

spec