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Forum: MechMates already cutting Sat 21 June 2014, 21:13
Replies: 382
Views: 225,107
Posted By Richards
Steve Stallings at PMDX designs break-out boards...

Steve Stallings at PMDX designs break-out boards properly. He uses a 10k pull-up resistor on critical inputs. His 10k plus an external pull-up is equal to 5k, which is very close to the 4.7k value...
Forum: MechMates already cutting Fri 20 June 2014, 17:19
Replies: 382
Views: 225,107
Posted By Richards
Pete, I'm sorry about the quality of the image....

Pete,
I'm sorry about the quality of the image. I use Eagle, which exports the image. As far as I know, there are no controls to darken the image. The resistors on the diode side should be sized...
Forum: MechMates already cutting Fri 20 June 2014, 12:10
Replies: 382
Views: 225,107
Posted By Richards
Fox, I agree that your schematic will work, but...

Fox,
I agree that your schematic will work, but I also know that it will not work forever. Thirty-nine years of experience building process control computers lets me know that attaching multiple...
Forum: MechMates already cutting Thu 19 June 2014, 09:00
Replies: 382
Views: 225,107
Posted By Richards
Here's a schematic that shows the use of...

Here's a schematic that shows the use of opto-couplers that have PNP (sourcing) inputs. The 7408 chip shows how I would connect the 4N27's outputs. Each output goes to a single input. On the 7408,...
Forum: MechMates already cutting Wed 18 June 2014, 06:09
Replies: 382
Views: 225,107
Posted By Richards
A 4N27 can sink very little current. It's rated...

A 4N27 can sink very little current. It's rated at about 30% efficiency, which means that if you size the resistor on the diode side to allow 10mA to pass, the transistor side will only sink about...
Forum: MechMates already cutting Mon 16 June 2014, 08:54
Replies: 382
Views: 225,107
Posted By Richards
All grounds should be connected together. In...

All grounds should be connected together. In other words, don't isolate one power supply from another.

Solid State Relays require a minimum load to work properly. If the load is too light, they...
Forum: MechMates already cutting Fri 26 February 2010, 09:30
Replies: 382
Views: 225,107
Posted By Richards
I need to clarify something. (It's probably...

I need to clarify something. (It's probably already been written by me or by someone else, but I have almost zero short term memory, so please put up with my rambling.)

The PK296A2A-SG7.2 motor...
Forum: MechMates already cutting Fri 26 February 2010, 06:18
Replies: 382
Views: 225,107
Posted By Richards
I think that we all agree that reducing the...

I think that we all agree that reducing the current going to the motor allows you to use a higher voltage; however, (there's always a 'however') a stepper motor is not a resistive load. A resistive...
Forum: MechMates already cutting Thu 25 February 2010, 14:44
Replies: 382
Views: 225,107
Posted By Richards
John, The laws of physics are not something...

John,
The laws of physics are not something that we can change to suit our needs. If a motor has an inductance rating of 2.2mH or higher, it can be used with a power supply whose MAXIMUM voltage is...
Forum: MechMates already cutting Thu 25 February 2010, 13:33
Replies: 382
Views: 225,107
Posted By Richards
John, We're dealing with the laws of physics,...

John,
We're dealing with the laws of physics, particularly Ohm's law.

Heat (Watts) is Amps (current) X Voltage. Run a few numbers and you see that heat (Watts) increases as the square of the...
Forum: MechMates already cutting Thu 25 February 2010, 11:24
Replies: 382
Views: 225,107
Posted By Richards
John and Ries, You both posted while I was...

John and Ries,

You both posted while I was working on my other post.

Geckodrive is in the middle of redesigning its stepper drivers. They have released the G250x (which is now included in the...
Forum: MechMates already cutting Thu 25 February 2010, 11:14
Replies: 382
Views: 225,107
Posted By Richards
Gerald, I agree. Voltage is the...

Gerald,

I agree.

Voltage is the parameter that mostly affects speed and current is the parameter that most affects torque.

When we look at the heat that a motor produces, one thing that is...
Forum: MechMates already cutting Thu 25 February 2010, 08:40
Replies: 382
Views: 225,107
Posted By Richards
I've come late to this thread, but I'm a little...

I've come late to this thread, but I'm a little concerned about the power supply and the motors.

The KL34H260-42-8A motor has 1.65mH inductance when wired bipolar parallel or half-coil. 32 X...
Showing results 1 to 13 of 13

 
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