Circuit to surpress voltage ramp up

[MagnetronMan]

I have a problem, I have a 12v 5a supply. when power is put into the circuit the rate at which the motor increases to fast. I needed a circuit to automatically introduce a gradual ramp up once the motor is switched on.

I am revisiting my college days and everything is hard to remember.

Was under the impression of using a simple resistor and capactior circuit? Will this work.
Should it be series or paralell and what values of components do i need.

Please help, kinda promised my boss i would sort it.

 

[duke37]

Anything in parallel with the motor will use power and will not affect the motor speed unless you are mistreating the PSU with exessive overload.

You could put a resistor in series with the motor and then by-pass it with a relay after a short time.

You could put a FET in series wih the motor and gradually turn it on with a resistance and capacitance. This is the prefered option.

You do not say the time scale that you are interested in, the fet solution could be used for times from a few milliseconds up to minutes.

These methods control the current into the motor and the rate of speed increase will depend on the load. If you want a more defined speed increase, then you will need voltage control which will be more complex.

 

[TBennettcc]

Are you working with AC or DC?

What is the current draw of the motor? If it's AC: Is it a squirrel-cage motor? Does it have a start capacitor?

 

[MagnetronMan]

ok

ok you have answered my problem, it is an error where the motor is switched on, just a gradual increae up to full power, no specific time. just a nice curve relative to voltage is fine.

what value components will i need? i think the FET is not required just the resistir and capacitor should do?

The supply is AC and does not have a start capacitor. it is a small inductive motor.