[tyutyi]

Thank you Phil for your fast reply.

I'll try to change the things, that you adviced.
I will post if these modifications helps or not.

Thanks again.

[lynx]

Hi!


I build the circuit what linked Tyutyi. Tyutyi ploted, I build.
Changed this parts:

potmeter 10k -> potmeter 1k
FET's resistors 4 x 2.2k -> 220Ohm
get out 2 x 1N4007
get out R14(2.7k) -> envelope
on the potmeter middle stick and GND among 100nF capicator (ceramic)

test power supply's
motor: DC 16V/20W
circuit: stabled DC 5V/3W

test
On a potmeter middle stick od REF 0-1.3V controllable.
But the motors current not changed! Twirl potmeter, current stable DC 1.3A.

Any idea?


Thanks, and sorry my bad english!

Lynx

[lynx]

up

[ggg]

There are some things that aren't the best in the circuit. The 74F08 isn't the best to drive the mosfet, a 74AC is a better choice. The 2.2K gate resistor is awfully high. You can compare it to my unipoar circuit: http://pminmo.com/l297unipolar/l297unipolar.htm

Phil

Phil, I did your 297unipolar driver, with a gate resistor of 47ohm. The problem I have it's like the chopping don't work well. Sense resistors(0.22 -3w) start to heat when I try to drive 3.6Amp 1.4ohm motor at 35vcc.
Do you think I have to add a mosfet driver like totem-pole?
Could Rsense's filter cause problems?

[pminmo]

I would need to see the physical layout, copper routing and schematic to look for the issue. I would first suspect the physical routing of the pcb.

[naren309]

Dear Pminmo,

i have made your unipolar stepper controller using fet. but fet IRL640 get very hot and burn. i am also using heatsink. the motor works fine with good torque but fets get very hot and burn within 5 minutes. i am not using any fast recovery diodes. i am using 0.5 ohm resistor 5 watts and motor is 140oz
can you please help me.

naren

Assuming your using the L297 to control unipolar steppers, you will need to use and logic similar to my circuit here:
http://pminmo.com/l297unipolar/schematic.pdf

More info here:
http://pminmo.com/l297unipolar/l297unipolar.htm

You would be using the BDX's in stead of the Mosfets. Add 270 ohms from the and gate outputs to the base of the bdx's. Emiiters wired the same as the source of the mosfets.

[pminmo]

Look through the appropriate threads on my bulletin board: http://pminmo.com/phpBB2/ If you still have a qustion post it there for an answer. That way it helps the next person that might have the same question.

[tyo]

Assuming your using the L297 to control unipolar steppers, you will need to use and logic similar to my circuit here:
http://pminmo.com/l297unipolar/schematic.pdf

DEAR PMINMO, your schematic shown R9 and R10 = 10 K, and C9 and C10 = 220pF...
what is use for.???
i got this link where to unable use these Resistor.(page 72)

CNC robotics: build your own ... - Geoff Williams - Google Buku

(sory for my bad english):cheers:

[pminmo]

Noise filter on the current sense lines.

[tyo]

thanks Mr. Phill that's important to reduce the noise.... hmm..hmm...
and.. my second question....
it's about oscillator...as your picture attach, you use RC network on 51K and 100pf... what the advantage between use 22K and 3,3nF..??
I've measured it using an oscilloscope, but the frequency is not stable ...( i use 22k and 3,3pF).
Where should I put the probe?? whether the pin 16 or pin number 1 ..???

my regard --ty0--

[pminmo]

thanks Mr. Phill that's important to reduce the noise.... hmm..hmm...
and.. my second question....
it's about oscillator...as your picture attach, you use RC network on 51K and 100pf... what the advantage between use 22K and 3,3nF..??
I've measured it using an oscilloscope, but the frequency is not stable ...( i use 22k and 3,3pF).
Where should I put the probe?? whether the pin 16 or pin number 1 ..???

my regard --ty0--

I just went with a different frequency.