Hi there community,

thank you in advance for any help as I am going desperate with this project
I am somehow of a self learner (safey first always a priority) thus some theory along with a lot of trial/error is how I develop my passion for electronics as my professional life does not allow me too much time to go deeper on a sustainable way of study the subject.

The ideia is to feed the 555 astable circuit (example that I´m using is attached) with a 12V solar panel.

The timer is working the way it was projected so "I got that going on for me" . The objective is to activate a dimmer circuit of an universal motor (withdrawn from a old washing machine) connected to the 220v electrical network in order to make a watering system for my vegetables garden.

The Dimmer circuit (example of what I am using is also attached) is also working, but the problem is that I cannot make it to be activated by the 555 timer circuit. So both circuits work but only on a segregated way. When I connect the 555 timer output (3rd pin) to the gate of the Triac (Diac also connected on that gate) I lose the ability to control the on and off of the universal motor dimmer, meaning the motor is always running.

As I have a big garden I would like to have this dimmer option in order to control the motor speed when I only need to water some parts of the garden.

Any advice for the option presented or any other that may mean to use a different approach would be forever appreciated!

I would prefer to avoid commercial options as I wanted to have the feeling of bulding something by myself in order to have that magical feeling of creation

 

This application note may help you.

 

You can implement the 555 circuit with a MOSFET and a Bridge Rectifier feeding the motor. So instead of AC across the motor feed the AC into a bridge rectifier and put the motor on the DC side with a MOSFET control on the Drain terminal. You can isolate the MOSFET Gate pin from the 555 with an opto coupler.

 

As I have a big garden I would like to have this dimmer option in order to control the motor speed when I only need to water some parts of the garden.

How are you controlling or limiting to 'some parts' of the garden?
The Universal motor operates in a run away condition.
If you start to restrict the output of a Universal motor, the load decreases and the rpm rises for a given voltage.
Depending on how you are doing it, you may be working at cross purposes.
For Triac control, see Fairchild AN-3006
Max.

 

This application note may help you.

Hello Alec_t,

thank you very much for your input. I´ll give it a look for sure

Best Regards

 

You can implement the 555 circuit with a MOSFET and a Bridge Rectifier feeding the motor. So instead of AC across the motor feed the AC into a bridge rectifier and put the motor on the DC side with a MOSFET control on the Drain terminal. You can isolate the MOSFET Gate pin from the 555 with an opto coupler.

Hi there Dodgydave,

highly appreciated your input

I think I got the idea, but if I could have something more tangible (i.e draw on how to make the connections) it would be a blast as I am a self taught and can´t yet "see on my mind" the tangible parts of your suggestion

Nevertheless, thank you very much for your input

Best Regards,

 

How are you controlling or limiting to 'some parts' of the garden?
The Universal motor operates in a run away condition.
If you start to restrict the output of a Universal motor, the load decreases and the rpm rises for a given voltage.
Depending on how you are doing it, you may be working at cross purposes.
For Triac control, see Fairchild AN-3006
Max.

Hello Max,

thank you for your observations and time

The limitations of the water in some parts of the garden will be made with taps alocated to the hose network system. Thus meaning, all the taps are open then I will need more pressure on the hose network system thus I need more pressure/speed on the motor. Some taps closed thus less pressure/speed on the motor. This is the idea. The timer only comes on the picture to "help" me on the times I am not at home.

I will give it a look on your Triac control suggestion.

Best Regards,

 

Hi there Dodgydave,

highly appreciated your input

I think I got the idea, but if I could have something more tangible (i.e draw on how to make the connections) it would be a blast as I am a self taught and can´t yet "see on my mind" the tangible parts of your suggestion

Nevertheless, thank you very much for your input

Best Regards,

Here is a sketch using an optocoupler Moc8204M, Choose R to enable the get the Fet to turn on probably around 10K , choose a MOSFET with high voltage D/S , best solution is to use a simple light dimmer, but as Max says, universal motors don't work well under load with reduced voltage..

 

Here is a sketch using an optocoupler Moc8204M, Choose R to enable the get the Fet to turn on probably around 10K , choose a MOSFET with high voltage D/S , best solution is to use a simple light dimmer, but as Max says, universal motors don't work well under load with reduced voltage..

Uau Dodgydave,

thank you very much for your time dedicated to my personal challenge. Your sketch made it much more clear.

Thank you very much