Gecko G250s VS. G540

[noisillator]

If I buy three Gecko G250s, will they provide the same functionality with Mach3 as three channels of the G540? I don't need spindle speed control or a fourth axis.

[jalessi]

Noisillator,

You will need a BOB (breakout board) other than that the G250 with provide the same stepper motor functionality.

The G540 has a charge pump, the G250 does not.

There are a few breakout boards that have a charge pump.
It is a nice safety feature.

If you don't want to use IDC cables or connectors you may want to consider the G251 instead of the G250.

The G250 has a IDC header.

The G251 has a screw type terminal.

Jeff...

[noisillator]

Originally Posted by jalessi Noisillator, You will need a BOB (breakout board) other than that the G250 with provide the same stepper motor functionality.

Who sells those? I don't see them on the Gecko site.

If you don't want to use IDC cables or connectors you may want to consider the G251 instead of the G250.

Screw terminals are a little easier, of course, but I can work with either type. Are these two driver boards essentially the same otherwise? The G251 is said by Gecko to be a "miniarized version of the G201," whereas the G250 is described as "the drive that forms the control interface of the G540." Because of this, I just assumed there were differences other than the connector interface.

[ger21]

The G250 and G251 are the same drive. The G251 is a G250 with a heatsink and screw terminals. The G540 uses the G250, as they plug directly into the motherboard.

[jalessi]

Noisillator

If you decide to use the G250's be prepared to spend some serious money for a breakout board unless you can make your own.

http://www.candcnc.com/EZPlug250-5.htm

I would use the G251 and one of these.

http://www.kelinginc.net/KL-DB25.pdf

Jeff...

[Jeff-Birt]

Also keep in mind that the G540's built in BOB is optically isolated. Optical isolation is a necessity in my book. It is also plug and play. A great value really. Everyone I have sold has made the new owner very happy.

[phomann]

Originally Posted by noisillator If I buy three Gecko G250s, will they provide the same functionality with Mach3 as three channels of the G540? I don't need spindle speed control or a fourth axis.

Hi Have a look at this thread here. I've done a schematic for a 4 axis system that uses G251s. You may find it useful.

Engineering Note for a 4 Axis G251 Controller

Cheers,

Peter.

[noisillator]

Originally Posted by jalessi Noisillator If you decide to use the G250's be prepared to spend some serious money for a breakout board unless you can make your own. http://www.candcnc.com/EZPlug250-5.htm I would use the G251 and one of these. http://www.kelinginc.net/KL-DB25.pdf Jeff...

Well, the G250s would actually fit my situation better. In fact, after reconsidering the G250s VS. the board from HobbyCNC, I now realize I have an old power supply that could be modified if I use the G250s. The supply is in a steel case with a fan on the back, and two sides of the case have large, finned heatsinks mounted. All the controller circuitry would fit inside the case, and the G250s could mount directly to the existing heatsinks (with appropriate insulators).

The thing is, this supply isn't a good fit for the HobbyCNC board. It was originally a commercial design specified at 13.8 VDC at roughly 40A. I inspected the transformer this evening, and its centertapped secondary measures about 33.5 VAC without a load. That means it can produce either 24 VDC using a full wave rectifier, or 47-48 VDC with a full wave bridge. The lower voltage isn't enough for either controller, but 48V is just right for the Geckos. That means this supply could narrow the cost difference for me between the two systems. Aside from that, it's been hangin' around the house for nearly 10 years. I've just been waiting for the chance to turn it into something useful.

Thanks for the tip on the Keling KL-DB25 BOB. $25 and it's even opto-isolated!