softer start for dc motor

[Redge2]

I have a dc motor that comes from a 18V corless drill. I made a small waterpump that will pump maybe 10minutes at a time 5times a day maybe 20 days a year.
I use the motor to drive the pump. The problem is it has a very thin shaft and becuase it starts at full speed immidiately when it starts, it breaks may attachement to the waterpump. It draws 1.12 amps at full speed,I use a 12v battery to drive it. Is there a simple electronic circuit I can build to cause it to get to full speed in maybe .5 seconds or 1second instead of immidiate full speed? So that there is not so much force on my attachment mechanism?
It does not have to be variable, just soften the initial start every time.

 

[Nigel Goodwin]

The obvious answer is a small PIC driving a suitable FET (needs to be a LOT bigger than 1.12A) with PWM. The software in the PIC simply needs to slowly increase from zero to full power over however long you want it to take, easily adjustable in the software.

Or if you don't have PIC stuff, an Arduino would be a simple choice, as it's a complete system rather than just a chip.

There's an example you could work from here:

PWM Control using Arduino-How to Control DC Motor and LED using PWM

In this article learn PWM generation and control using arduino. Learn how to control DC motor speed using PWM and learn to control LED brightness

www.circuitstoday.com

But that uses a small motor and a small transistor, you would need a decent size FET in it's place.

 

[Redge2]

Thank you Nigel i will look at it