The main benefit of Gecko's is the microstep to full step morphing, plus they're small!
I've got 2 G251s in my lathe, and can't fault them.
I did think about getting the G540, but it wouldn't of fitted in the control housing, and I already had the SmoothStepper and C23 break out board so didn't really need any of the additional features of the G540. If I was to start from scratch, I probably would go for the G540, as it does most things you need (inputs/outputs/0-10V speed control) in one plug and play package. Just add power, a parallel cable, some steppers and resistors, and you're good to go.
If you do still consider the G540, look at the GC-02 and GC-04 connectors from www.homanndesigns.com, as they make wiring even simpler!
Also, the Gecko customer appreciation sale must be about due, so if you're not in any hurry, keep an eye out to get the drives even cheaper than what the UK importer charges
The Following User Says Thank You to m_c For This Useful Post:
I'm just reading about the 540's and doing a side by side with the Kinco 2M880N (that was top of my list...)
I don't know what "microstep to full step morphing" is, or if there is any advantage of "256 microsteps", my reading list just got a bit longer!
I wonder if the gecko's use vector current control, like the 2M880N, bet they don't...could be wrong.
To me it's obvious - get the 2m880N as that's about 50% higher voltage than the gecko which should have a much greater affect than the rest of it.
No point in using 256 microsteps ... that high wont help with accuracy (only cheating yourself if you think the resolution is 256th of full step resolution). As long as the driver does up to about 10 microsteps that's fine.
More info on microstepping here, here and here:
Other websites are available ...
Your blood pressure can go down as well as up if you choose to read them ...
Last edited by Jonathan; 19-09-2011 at 09:41 PM. Reason: Numerous
Thanks Jonathan, lol, I got as far as "Magnetic backlash" and decided I need far more coffee than I've had already! I'll leave it for tomorrow! :-)
I'll certainly keep an eye open for the sale! Thanks for your help!
I'll compare with PM752 driver as that's what I have. Copied from Gecko site:
3.5A 50VDC maximum PM752, 75V & greater current
Digitally filtered STEP, DIRECTION and DISABLE inputs same
3.3V and 5V logic compatible inputs Same I think, can go higher with resistor. Also if you accidently pop one with 75V it's easy to replace the optoisolator :naughty:
300 kHz maximum step pulse frequency same, but who needs more than about 50kHz anyway
Top settable Adjust trimpot None
Power LED indicator same
No user settable jumpers PM752 has internal jumpers for motor direction and something else I can't remember ... not much use really
20 kHz switching frequency I'm pretty sure PM752 is much higher, will check it with scope tomorrow
Mid-band resonance compensated Probably none
Microstep to full step morphing at higher speeds Probably none
Small size Nobody cares
Four layer PCB That just means they weren't good enough to make it 2-layer
Discrete all N-channel MOSFET full bridge design same
14A rated power MOSFETs PM752 mosfets are 33A and 100V, so will almost certainly have lower Rds and therefore power dissipation.
3.5mm 12 position connector with screw type terminal Pluggable, which in my opinion is better
Recirculate mode while the motor is stopped, reducing motor heating Probably none
70% current when stationary 50% on PM752 so possibly lower power dissipation - possibly not due to the above, can be changed with a bit of effort
Maybe I should have compared with a different Gecko, but you get the idea.
One more for your reading list:
Looks like vector control is one up from resonance damping.
Last edited by Jonathan; 19-09-2011 at 11:42 PM.
'The application of advanced vector control algorithm greatly reduces noise and vibration of the motors during operation, '
The link I gave in my previous post explains it better. In particular this is interesting:
'The motor operates in continuous mode rather than conventional stepping mode.The audible
noise and resonance effects associated with conventional stepping mode are effectively
That sounds alike to the Gecko - although it's not full stepping at higher speeds it's applying a sine wave to each phase, so operating it like a 'normal' motor not stepper motor. Bound to be quieter and more efficient for obvious reasons.
I'm intending to implement vector control on the stepper driver I'm designing/prototyping.
The formula you are probably using to say they are 20V over-spec (32*sqrt(L)) is almost certainly an oversimplification / guideline. I think the fact my real life experience with these motors shows the temperature is fine at 75V says it all.
Last edited by Jonathan; 19-09-2011 at 11:54 PM.
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