Zohar,
If you read the link in post #9 you will find that it uses the same basic principle as Dave has described.

Les.

 

Reading it now.
(opened it before, but it was held aside..)

Thank you

 

Again do read what you post? When a motor especially a DC motor starts to stall, it demands more current not less. You continue to mislead people.

Maybe you should read what you post!

https://physics.stackexchange.com/q...rs-draw-current-even-when-they-are-not-moving

 

Here is one method, with an oscillator and comparer using a LM358. .

View attachment 165033

My guess is that if a single op-amp can produce something like a saw-tooth /triangle wave, the second op-amp may act as a comparator to give a voltage controlled PWM. The transistor, as mentioned, just amplifies that to power the motor.

That is a typical circuit using 3 op-amps (two to produce the triangle/saw-tooth wave). I was not aware of the single op-amp saw-tooth/triangle oscillator.

 

There are dedicated chips to produce PWM..
Which can save the designer of the circuit to implement it, using components like this..

 

There are dedicated chips to produce PWM..
Which can save the designer of the circuit to implement it, using components like this..

True, but if you are making several million for export, every 1% is $10,000 x "several" to take home. Hence the use of old chips with no discernible difference in performance.

 

Maybe you should read what you post!

https://physics.stackexchange.com/q...rs-draw-current-even-when-they-are-not-moving

Like I said go back and read the link you posted. An electric motor draws its highest current when under load, when it is getting full voltage and something(load) is slowing it down. And at it's start it is not turning is just like when it is under load. You do understand that a motor under load is a motor not turning its proper RPM don't you?

 

Here is one method, with an oscillator and comparer using a LM358. .

View attachment 165033

In my opinion, you can do without a stabilizer when powering the drill from a voltage not exceeding 20 volts. The nominal potentiometer can be increased.

 

What don't you understand !? Because it demands more current, we have a regulation to reduce it!

Don't keep trying to convince me of something that YOU believe that is just not true. Spend the time trying to understand and learn.

 

Fake news-DT

 

Fake news-DT

Explain?