7i96S PSU

This is a hobby robot project with mostly Nema 17, so I was targeting 5 & 25 vdc, on a budget.

Hobby Robot

rodw wrote:

You have to be careful here. I have a 12v/5v Meanwell power supply (in a frame) that is useless for this because the 5v side needs a load on it for the 12v side to work. The required load far exceeds the power draw of a Mesa card. It was suggested I add a ceramic resistor but the generated heat and power consumption made me scrap the idea.
 

Good catch Rod.  It's been a few years, and I completely forgot I had to add a resistor to get the 12 & 24v outputs to work.

Having said that, the PSU (with resistor) has been in (mostly) daily service with no issues.

Just thought I would upvote the din rail MDR-10-5 and also mention the NDR-120-24v as a possible option for
the drivers depending on the max current requirements for your motors.

Using din rail power supplies can help to keep things more compact and tidy.

(I bought a MDR and a couple of the SDR (an upgraded NDR) series for the mill I am currently building and
really liked how much more convenient they were compared to the computer PSU I was working with initially.)

If you can get by on just 12v/5v, the computer PSU could be an option on a budget, I had one laying around so
my build started out using one, but it mostly got replaced by the mean well supplies I upgraded to. Keep in mind
that some hardware does not like to have input power supplied through a switch, it may not be the most practical
to have all of your power supplied from one source...

There's nothing wrong with using one of those little step down converters from Amazon just to power a Mesa card. I had pins soldered to one that went straight into the screw terminal connector of a 7i96, probably going on 3 years now supplied from the same 24v power supply.

Make sure you get one that you can solder a pad to fix the output voltage to 5v, those little trimmer pots are horrible.

At a glance a MDR and LRS Meanwell have similar specs with the LRS being cheaper.  Din rail mount is nice, but I'm trying to keep cost down.  

Any technical reason not to use a RS or LRS PSU for a Mesa board and Raspberry Pi?

Largest difference between the MDR and the RS or LRS is probably the arrangement of the input/output terminals.
(opposite sides vs same side) So wiring layout would be somewhat different. I don't have any of the LRS or RS so I
can't make much of a direct comparison, but looking at how similar the specs are, the price point on the LRS/RS is
a compelling point of consideration.

MDR is DIN rail and has power factor correction. LRS is the aluminum frame enclosed type with no PFC. LRS is pretty much the same as RS but it's physically smaller, usually a bit thinner.

I always use LRS or HDR series depending on where I have to stick it. PFC is more efficient but it doesn't matter that much unless your driving motors. If you have a 24v supply for steppers you'll probably want PFC, the 5v supply it's upto you but if it's a major cost difference I wouldn't bother. All of Meanwell's supplies are good, even the cheap ones.