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How to increase adc value softly

Started by Amod, Dec 21, 2022, 02:49 PM

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I want to increase adc value softly( just like soft start).



The ADC is an input, you can't increase it as it is not an output, or I misunderstood something?

Did you mean the DAC value? Which device, can you please elaborate your question?


Sir,i want to make soft start for my dc drive.


Is the motor supply DC or AC? How big is the motor, what is the motor voltage and what is the resistance across the terminals? The resistance helps to work out the starting current.

Variable DC drive using DAC needs a quite complicated amplifier, much better to use pulse width modulation. It can be done using software but a PIC with HPWM module is better.


DC motor is self magnet.only armature voltage is to be applied.
We need 0 to 180vDc to make speed variable.Iam using two thyristor to make dc voltage variable.

I tried using PWM to to trigger thyristors but it didn't work.

Kindly help with a suitable circuit for firing two thyristor using pulse transformer.
Iam using 16f877A.

Motor takes 5 amp maximum.

Iam converting 230V Ac to


Ok, so how will you set the speed, using a potentiometer or digital?

First you need zero crossing circuit then calculate the delay needed to control the speed.

How far have you got with the project.

I will try to help more but I am not at my main computer


I will set speed by 10k potentiometer.

I have only sucessful generating PWM controlling by potentiometer.

John Lawton

As has been said, you need to generate pulses to fire your thyristor (or triac) using phase control. This means you trigger a delay timer from the AC power zero crossing pulses using a circuit like the one I provided here:



A program for zero crossing detection will help me a lot.


Is it the same supply for the motor and for the PIC




Still working on your problem.

The zero crossing was easy, now i am working on the output timing.


Quote from: See_Mos on Dec 28, 2022, 11:17 PMStill working on your problem.

The zero crossing was easy, now i am working on the output timing.