# Thread: Hobbycnc ez driver board + Mema 23 at 5v each?

1. ## Hobbycnc ez driver board + Mema 23 at 5v each?

I think I have just got confussed in worry on this one

I bought the hobbycnc ez driver board kit and I dont want to damage it by doing a daft mistake (cant see all the info I need on the site).

I was going to run 36v through it but now now I dont need to as I have Nema 23 motors rating at 5v each so I was woundering

if I placed 24v in as there is a 24v fan out how would I work it so the motors get only 5v each?

sorry for maybe such a daft question as I am not to fully sure on how the power out works on the boards, I take it splits the volts into 3 some how (ie. say 30v would go 10v each motor)

hope someone can shed some light on this for me,

extra question why am on it do you know where there is any infomation about the limit switch idea on the board? (like diagrams etc)

2. Doh scrap that about the power needed I just found my answer as I carried on looking lol that allways happens after 2 hours of looking then asking sorry.

but if some one could point out about the limmit switch bit that would be great?

Answer for my question for some one else if needed:

I will be placing 36v as I planned at the start as the stepper motors should take it and work better, the board can take a max of 36v and my PSU is around 35. something volts so should be good.

well that the short answer on what I read but if some one think I am wrong please say as I dont want to be wrong for me and others

3. ## Re: Driver Voltage Concern w/ 5v Stepper

Hi. Here's the basic idea behind what's going on that they don't come out and explain. This driver board (and apparently most "stepper" drivers (vs. "servo" drivers)) supply voltage to the stepper coils as a pulse. The "effective or working" voltage (technically the RMS voltage (vs. peak) but don't worry about that) across the coil is approximately equal to the ratio of the time the voltage is on vs the time it's off (it's actually closer to ((on/off)*.707), but that only concerns the designers).

Anyway, if the pulse is on 50% of the time and off 50% of the time, then the average voltage across the coil is approximately half the supply voltage. (36V supply yields 18V effective voltage across the stepper's coil.) 33% on to 66% off is 1/3 the supply voltage = 12V and so on. (Again it's actually less than that, but you get the idea.)

These circuits change the voltage by varying the width of the on to off part of the pulse which is actually called Pulse Width Modulation (changing the pulse width of on vs off). A circuit that does this (like a CNC driver board) turns the voltage on and off to make the pulse. This is also called "chopping" the supply voltage (cutting it on or off rapidly). So the driver is called a chopper driver.

Sorry if this is more than you asked for, but this is the magic behind why you don't burn out a 5V motor with a 36V supply and a chopper driver board. The chopper driver drops the effective or working voltage across the coil to a safe range. One of the advantages to hitting the coil with a higher than rated voltage is that it responds a lot faster than it would if you were pulsing a 5V supply to the coil.

Best regards,

Scott

4. You still trying to figure out the limit switches?

#### Posting Permissions

We are the largest and most active discussion forum from DIY CNC Machines to the Cad/Cam software to run them. The site is 100% free to join and use, so join today!