Thread: Bipolar Microstep 48 volt 5Amp /phase, 4 axis board

**contactirfu** · 09-10-2007, 03:51 PM

How's the board coming up Kreutz.

Whats more.....

**kreutz** · 09-11-2007, 03:02 AM

Originally Posted by contactirfu

How's the board coming up Kreutz.

Whats more.....

I think I will be able to complete and test the first prototype next weekend. Good News!! My friend had a very promising job interview.

Regards,

Kreutz.

**contactirfu** · 09-11-2007, 04:21 AM

Originally Posted by kreutz

I think I will be able to complete and test the first prototype next weekend. Good News!! My friend had a very promising job interview.

Regards,

Kreutz.

Great News! On second thoughts are you hinting that this project might not be taken up for production.........

Just Kidding...

RGD
Irfan

**kreutz** · 09-16-2007, 03:22 AM

SMD component holder.

Thanks, Pminmo!! Here is my version of your device. I couldn't have done it without your help.Today I realized I still needed to order a few more parts before reflow...

**David_Web** · 09-16-2007, 03:10 PM

That is reely nice :idea:
Yep that was a pun. :violin:
Great to see things moving.

**pminmo** · 09-17-2007, 02:04 AM

Originally Posted by kreutz

SMD component holder.

Thanks, Pminmo!! Here is my version of your device. I couldn't have done it without your help.Today I realized I still needed to order a few more parts before reflow...

looking good....

**cephjedi** · 09-17-2007, 03:37 PM

Neat stuff, Kreutz!

To the uninitiated, it looks like you're weighting down spools of candy buttons with a shaved computer motherboard.

Good Luck to your friend on that job lead! That's great news, I hope it pans out. In the "really really late to the fire" category: Over the weekend I was thinking about your project and your friend's situation and wondered if you considered taking pre-order deposits.

I bet more than a few of us forum subscribers would be willing to pony up a good faith deposit to get one of your first run. CNC zoners are by and large so cool I doubt there would be any additional pressure to meet any deadlines- I certainly wouldn't harp on you. If anything, it buys you time and helps with the cash flow both for your friend and the project.

Cheers, Jim

Looking forward to the completed controller as well as first reviews! (can't get that super fast spinning stepper video out of my mind!)

**kreutz** · 09-17-2007, 07:39 PM

...Over the weekend I was thinking about your project and your friend's situation and wondered if you considered taking pre-order deposits...

That was never an option. I have to rely on my free time, and, as you see, it can't be taken for granted in my current job, so I would have felt really uneasy if I had done that.

Even if my friend gets a new job, I will finish this project, please, be patient.

Regards,

Kreutz.

**kreutz** · 09-17-2007, 08:52 PM

Some of the more than 350 parts (this size) on the 4 axes board.

Note: The penny is there for size reference only.

**cephjedi** · 09-17-2007, 08:57 PM

I do understand. No pressure from me! Take your time and get it the way you want it.

Speaking of which: I'm tinkering too much with my machine. I scored some great linear bearings on eBay and can now rebuild my my machine as a moving-gantry design, greatly opening up my work area. Which means I will probably start cutting parts for a Joe2006 model. They tell me the first step with CNC addiction is just admitting I have a problem....

Cheers, Jim

**cephjedi** · 09-17-2007, 08:58 PM

Ha! Don't sneeze!

-J

**kreutz** · 09-17-2007, 09:01 PM

Originally Posted by cephjedi

I do understand. No pressure from me! Take your time and get it the way you want it.

Speaking of which: I'm tinkering too much with my machine. I scored some great linear bearings on eBay and can now rebuild my my machine as a moving-gantry design, greatly opening up my work area. Which means I will probably start cutting parts for a Joe2006 model. They tell me the first step with CNC addiction is just admitting I have a problem....

Cheers, Jim

The real addiction shows when you haven't even finished the machine you are working on, and you are already thinking about the next one...

**kreutz** · 09-18-2007, 09:15 PM

Most of the missing parts already arrived. There is one on back order supposed to arrive this week. Even if that one is not here by the time I do the reflow soldering, it will be easy to solder manually later.

**kreutz** · 09-19-2007, 01:17 PM

I began to investigate what the costs associated with professionally assembling the SMD boards are. Looking for a less than 200 boards run, probably about 50 - 100, depending on costs.

So far I have a couple of quotes, but I still think we can get a better deal. Otherwise, I will have to split the board in two, an SMD interface board, and a "through-hole" power stage board. That way it is going to be easy to test the SMD board after assembled, and will also reduce the PCB cost a little more because it doesn't need to be a 2 Oz Cu PCB, although is going to add two more connectors and a multi-wire cable (I am thinking about using a 40 pin IDE hard drive drive cable between the boards...)

**contactirfu** · 09-19-2007, 03:17 PM

Originally Posted by kreutz

I began to investigate what the costs associated with professionally assembling the SMD boards are. Looking for a less than 200 boards run, probably about 50 - 100, depending on costs.

So far I have a couple of quotes, but I still think we can get a better deal. Otherwise, I will have to split the board in two, an SMD interface board, and a "through-hole" power stage board. That way it is going to be easy to test the SMD board after assembled, and will also reduce the PCB cost a little more because it doesn't need to be a 2 Oz Cu PCB, although is going to add two more connectors and a multi-wire cable (I am thinking about using a 40 pin IDE hard drive drive cable between the boards...)

Kreutz,

Probably I can get a few quotes from India, and also quotes to get them professionally assembled here. Might cost much more cheaper!

What Say!

RGD
Irfan

**david_geng** · 09-19-2007, 10:07 PM

Originally Posted by kreutz

Using a TVS is a simple and effective way to protect against very short time, low repetition rate, high energy surges. Each power mosfet internal diode has a clamping voltage and some capacity to withstand medium energy (in the hundreds of mJ) short time surges too, but aren't as fast, the Snubbers have double function of limiting dV/dt, and limiting the peak surge voltage during the reverse recovery time interval after turning off the mosfet with an inductive load, helping to control the voltage spike before clamping occurs, in the worst case scenario, while dissipating part of that energy.

The problem with a TVS only protection, in our case, is that the power IC published absolute maximum voltage is too near the working voltage (52 volts and 45-48 volts respectively), TVS are not designed to withstand long time over-voltages (and clamping voltages have a tolerance range), then there is the dv/dt issue that is also easily solved with the snubber.

For discrete H bridge output, I would opt for the TVS and mosfet's gate resistance controlled dv/dt.

The energy fed back into the power supply when quickly decelerating a motor (capacitor voltage increases due to this additional energy), is best controlled by de-rating the working voltage and/or using a power dump load if it becomes an issue. For low inertia loads I use a 300 ohm 15 Watt resistive load continually attached across the power supply capacitor's terminals.

Hi,

Maybe the battle for this reverse current problem has been finished already. I just wondered if it would be possible to have the MCU detecting such higher voltage and drive the low size MOSFETs.

Just a thought.

David

**kreutz** · 09-20-2007, 01:23 AM

Originally Posted by david_geng

Hi,

Maybe the battle for this reverse current problem has been finished already. I just wondered if it would be possible to have the MCU detecting such higher voltage and drive the low size MOSFETs.

Just a thought.

David

What is usually used to get rid of that extra energy is a comparator with the input peak voltage, if the capacitor voltage is higher than a preset level over the input peak voltage, then a mosfet is activated and excess energy is drained using a power resistor connected between the capacitor + bus and the drain of the mosfet (mosfet source connected to Ground). You can use a couple of A/D channels on the MCU (connected as differential input) to do the same thing too (then the MCU will control the Mosfet), if you have extra cpu bandwidth available.

**kreutz** · 09-20-2007, 01:51 AM

Originally Posted by contactirfu

Kreutz,

Probably I can get a few quotes from India, and also quotes to get them professionally assembled here. Might cost much more cheaper!

What Say!

RGD
Irfan

I will appreciate that.

4 axes Board data (still subject to changes):

Dimensions are 10 inches x 5.130 inches board. 459 total components. 60 different component part Numbers: 45 different SMD components (1 high density SMD < 20 mils between lead's centers) + 15 different through-hole components. Smaller SMD size 0603. No BGA components.

Regards,

Kreutz

**kreutz** · 09-26-2007, 02:48 AM

Assembling the Prototype

It took us (my wife and I) two hours to populate all the SMD components on the board, after applying the solder paste with the stencil. The whole board took less than 5 minutes to reflow using my modified Toaster Oven.

Even the high density SMD package soldered perfectly. No re-work required. After taking a break, I began to solder the through-hole components. The L6203s are not soldered yet, I placed them on the heat sink, then, on the board, just to show how it is going to look after finished.