Hello, I have an idea to make the impuls function on a makita brand cordless screwdriver.
It is very handy to unscrew old bolts, or to drill to shiny surfaces like tiles.

Unfortunatelly the impuls is metabo "inovation" - if you can call pulsed power to the motor inovation. It is available on few cordless drills, and I have one of them that's when I understool how handy this is.

You can see a video here how the impuls function works
http://www.youtube.com/watch?v=86l4Ft_xAr0

Is is possible to design a simple circuit with power fet, etc to pulse the power to the motor?
I'm sure a power fet, capacitor to select pulse cycle lenght and some other parts would make this doable for DIY project.

 

Watched the video. I don't see how this is beneficial in any way. I seems like the guy is just making up reasons why it is beneficial as he goes along. I am an automotive fabricator by trade, and this just seems gimmicky to me.

 

Hello, I have an idea to make the impuls function on a makita brand cordless screwdriver.
It is very handy to unscrew old bolts, or to drill to shiny surfaces like tiles.

Unfortunatelly the impuls is metabo "inovation" - if you can call pulsed power to the motor inovation. It is available on few cordless drills, and I have one of them that's when I understool how handy this is.

You can see a video here how the impuls function works
http://www.youtube.com/watch?v=86l4Ft_xAr0

Is is possible to design a simple circuit with power fet, etc to pulse the power to the motor?
I'm sure a power fet, capacitor to select pulse cycle lenght and some other parts would make this doable for DIY project.

"Impuls" seems like ultra-slow PWM.

 

Watched the video. I don't see how this is beneficial in any way. I seems like the guy is just making up reasons why it is beneficial as he goes along. I am an automotive fabricator by trade, and this just seems gimmicky to me.

I don't know how it seems it really helps, it is patented so other manufacturers do not want to pay for a patent so they do not have this feature. Before I got the Metabo LTX I have damaged many screws by using regular type makita, bosch screwdriver. At the end I needed to drill the screw head and use pliers to remove it (from wood etc.)

The Pulsating action makes it easy to unscrew:

1. screws with damaged head (rusted etc.)
2. crews with flat type head

It also helps at drilling holes into tiles or surfaces where drill bit can slip. It's not a gimmick.

 

I agree that there are circumstances where pulsed output is helpful. Even using the torque control can be useful to take out stubborn screws.

It should be easy to implement, a 555 and a mosfet could do the trick.

 

The Pulsating action makes it easy to unscrew:

1. screws with damaged head (rusted etc.)
2. crews with flat type head

It also helps at drilling holes into tiles or surfaces where drill bit can slip. It's not a gimmick.

I don't see how the pulsing magically gives a screwdriver bit better traction on a questionable screw head, or keep a drill bit in place. But either way, this would be really easy to implement using a 555 as your pulse generator and a FET or something that could handle the motor load.

 

I have made this other schematic myself by googling some MOSFET motor control examples and 555 timer circuit. However my simulator just blows everything up ;/ could somebody simulate this?

 

The schematic looks good to me, except that I don't know what D2 is for. And I don't use simulation software, but I think I have all the parts to breadboard the circuit. What is the pulse rate range you have designed for?

 

D3 and R3 combined make the MOSFET turnoff veeerrry slow. How about moving the switch?
Also, the diode needs to be across the motor, not across the MOSFET.
You should also add a series gate resistor, as close to the MOSFET as possible, to prevent oscillation.

 

The schematic looks good to me, except that I don't know what D2 is for. And I don't use simulation software, but I think I have all the parts to breadboard the circuit. What is the pulse rate range you have designed for?

D2 is to protech the MOSFET as described here
Simple Power MOSFET Motor Controller

http://www.electronics-tutorials.ws/transistor/tran_7.html

I would be grateful if you could breadboard this The pulse range is 2 a second so thats 2hz maybe 4hz

 

D3 and R3 combined make the MOSFET turnoff veeerrry slow. How about moving the switch?
Also, the diode needs to be across the motor, not across the MOSFET.
You should also add a series gate resistor, as close to the MOSFET as possible, to prevent oscillation.

Yes the diode across the motor before the switch did the trick now the back EMF does not spike and blow the MOSFET on my circuit.

Your circuit works fine except I want to turn off the 555 timer when pulse is off the batteries would be dead if left on forever.
My switch position is not optimal, perhaps there is a better place ?
Perhaps the screwdriver switch would turn off the 555 timer, because i off state the drill is off so the real switch is not like in diagram it can be off (neutral position)

 

I built the breadboard (without the switches) and it functions fine with an LED on pin 3 of the 555 and another LED on the drain of the IRLZ44. However, when I connect the motor, the pulse rate from the 555 runs full speed. I am guessing noise on the Vcc.

 

Yes the diode across the motor before the switch did the trick now the back EMF does not spike and blow the MOSFET on my circuit.

Your circuit works fine except I want to turn off the 555 timer when pulse is off the batteries would be dead if left on forever.
My switch position is not optimal, perhaps there is a better place ?
Perhaps the screwdriver switch would turn off the 555 timer, because i off state the drill is off so the real switch is not like in diagram it can be off (neutral position)

Every drill I have seen has a power switch and a forward/reverse switch. You have added a function, so it seems like you would need another switch.
Of course, most also have a speed control built into the trigger, along with the power switch. Not sure how you would incorporate that into the impulse function. It seems like you would want to control the impulse rate, but I don't know how you could do that, and still maintain the speed control function when impulse mode is off.

 

If memory serve me right, the drill speed control circuit utilises a SCR to control its pulse width.

So, maybe the 'impuls' function could be added to control the SCR's gate.
Requiring no further mod...

 

If memory serve me right, the drill speed control circuit utilises a SCR to control its pulse width.

So, maybe the 'impuls' function could be added to control the SCR's gate.
Requiring no further mod...

I'm not sure what SCR is but I wonder has somebody some example (all drill switches are the same more or less).
If modded externally the warranty would not be void so that is a plus for external mod.

 

Of course, most also have a speed control built into the trigger, along with the power switch. Not sure how you would incorporate that into the impulse function. It seems like you would want to control the impulse rate, but I don't know how you could do that, and still maintain the speed control function when impulse mode is off.

When you push the switch you vary the speed and torque (how many amps go to the motor), the MOSFET 555 timer circuit would simply turn on or off the battery pack that would result in pulsing action like in the video.

If you want slow pulsing you push the switch just a little bit, if you want strong pulses push some more. I would not like to modify the switch if possible because of warranty issues and because the switch is sealed on most models very hard to take it apart without damage. Some are filled with epoxy so once you open it you find out that all the work was for nothing.

I'm sure fitting SMD style parts for 555 timer and a singe MOSFET in any size screwdriver is possible. You can't use dre drill in pulse mode unless in specific conditions arise that means you will not use it for long periods of time - no overheat to the MOSFET, but small heatsink should be used I think.

 

I built the breadboard (without the switches) and it functions fine with an LED on pin 3 of the 555 and another LED on the drain of the IRLZ44. However, when I connect the motor, the pulse rate from the 555 runs full speed. I am guessing noise on the Vcc.

Hmm, what could be done to make the circuit work then?

 

Hmm, what could be done to make the circuit work then?

I added a .1 μF cap across the power pins of the 555 and put 2000 μF across the motor leads, which helped some, but not enough. Separate power supplies would work, but that's not practical.

 

I added a .1 μF cap across the power pins of the 555 and put 2000 μF across the motor leads, which helped some, but not enough. Separate power supplies would work, but that's not practical.

Perhaps something like ADR125 (ADR3450) would help.
http://www.analog.com/en/special-linear-functions/voltage-references/adr125/products/product.html

 

Perhaps something like ADR125 (ADR3450) would help.
http://www.analog.com/en/special-linear-functions/voltage-references/adr125/products/product.html

I don't think it's a regulation problem, but rather the motor is inducing noise on the power supply that is causing the 555 to reset and otherwise operate erratically.