[kreutz]

I played a bit with those long time ago. The problem with nichrome wire is that it needs special soldering flux which is chemically aggressive , so pcb must be cleaned very well otherwise there could be problem with joint due to corrosion. Or may be nichrome wire can be screwed to the pcb pad - that is another alternative . But info on the connection time stability must be found in order to know what to expect from this type of connection when product is aging.

That is why I told you to use an spot welder.

[mugabe]

Hmm, are you sure that nichrome can be welded to copper without problem? Is there need for material compatibility? Some dual metal joints can act as semiconductors or thermopiles .

[kreutz]

Hmm, are you sure that nichrome can be welded to copper without problem? Is there need for material compatibility? Some dual metal joints can act as semiconductors or thermopiles .

They will act as a thermocouple, but thermocouple voltages are in the microvolt range and won't interfere.

The good thing about spot welding is that it works better with high resistivity metals, because the technology uses electric current and contact resistance (plus pressure) in order to create heat and melt the contact area under the electrodes. You can weld nichrome to the wires used for battery leads (better than pure copper wires because they are already plated).

[H500]

37 - 44 cents per part is not that cheap i think , in fact those are nothing but piece of nichrome with copper coated steel leads attached.
Just curious can same nichrome from heaters be used instead ? The only question is how to solder/attach them to achieve soldering joint connection stability over the time.

They're cheap compared to the 15FR100's

It looks like copper wires welded on a metal strip.

[mugabe]

if i am not wrong, typical tempco for thermocouple is 40 uV/C . If taking self heating of resistor and assuming 50 C degree working temperature range - we get 2 mV of thermo voltage. using 0.1 Ohm for up to 6 A current will provide 0.6 V voltage drop . Looks like acceptable as it is less than 1 % of current measurement range.

[David_Web]

We need daily updates!!!
Nah just kidding. How is it going?

Is there a low voltage limit or will it work with nearly any bipolar or unipolar stepper that is wired as bipolar?
Any minimum current?
Can the current be adjusted steplessly or does it have fixed steps?
I can't remember if I read this or not but will it have current reduction feature that kicks in after a short while of inactivity?
Or would that be unnecessary and just add unwanted complexity and cost.

[kreutz]

We need daily updates!!!
Nah just kidding. How is it going?

Is there a low voltage limit or will it work with nearly any bipolar or unipolar stepper that is wired as bipolar?
Any minimum current?
Can the current be adjusted steplessly or does it have fixed steps?
I can't remember if I read this or not but will it have current reduction feature that kicks in after a short while of inactivity?
Or would that be unnecessary and just add unwanted complexity and cost.

Hello;

There is a maximum voltage of 45 volts and a minimum voltage of 15 Volts on the Motor's power supply, there is a maximum voltage of 18 volts and a minimum of 8.5 volts, at the +12 volt input, being monitored actively, if any of the voltages are out of limits, the outputs are immediately disabled, and Emergency Stop triggered.

The same occurs for Currents over 6 amps. Over-temperature is controlled by the L6203 internal circuit to a maximum of 150 degrees (Celsius), it has 15 degrees hysteresis...

Current could be continuously adjustable from 0.2 to 5 Amperes (Peak) for each channel. There is an automatic current reduction after 1 second inactivity.

The prototype boards are already here but I really haven't had time to begin working on them.

Thanks,

Kreutz.

[David_Web]

Thanks

I have browsed through a lot of drivers. They are ether way too expensive or is only cheap fullsteppers. (been there, done that and ended up with a broken board, luckily i just bought 1)
Yours seems to be the only alternative and at such a nice pricepoint and with all needed features I don't see how I can do anything else but to wait for it =)
Do you consider adding a jumper or similar to disable currentreduction on z axis, I think my motors will hold the load with no problem, even at reduces current. However it might be a problem for others.

I still have to construct the rest of the machine so don't worry about time for me. I value reliability over quick delivery.

[kreutz]

Thanks

I have browsed through a lot of drivers. They are ether way too expensive or is only cheap fullsteppers. (been there, done that and ended up with a broken board, luckily i just bought 1)
Yours seems to be the only alternative and at such a nice price point and with all needed features I don't see how I can do anything else but to wait for it =)
Do you consider adding a jumper or similar to disable current reduction on z axis, I think my motors will hold the load with no problem, even at reduces current. However it might be a problem for others.

I still have to construct the rest of the machine so don't worry about time for me. I value reliability over quick delivery.

I decided to incorporate automatic current reduction as a non user configurable feature because of the way the automatic torque compensation works.

During the micro-step phase of the speed range, step current tables use the peak current value set up by the user so the r.m.s. value of the current sinus-wave is equal to the motor's r.m.s. maximum value or Full-step current. When the speed reaches the intermediate morphing waveform stage, the peak current is internally modified on the tables, so to keep a constant r.m.s. value independent of the current form factor.

The same principle applies to the full wave part of the range. If you stop the motor on a micro-step corresponding with a peak current (1.4142 x Maximum r.m.s.) value on one of the channels, then the DC current value would be over the maximum (full-step) current, so it is necessary to reduce the current, and the automatic current reduction feature comes into play.

If a user wants to eliminate the feature, then it is necessary to use the non-torque compensated tables (commented in the source code) and recompile it, it is an easy task and I can provide the HEX files if it becomes necessary.

[David_Web]

Ah I see. I guess it won't be a problem most of the time as most people gear down or use a lower pitch for their Z

[kreutz]

Ah I see. I guess it won't be a problem most of the time as most people gear down or use a lower pitch for their Z

You can always use a reduction factor of 68% instead of 50% by changing two resistors. In that case The motor will stop with a current equal to the full step value and no damage will be done. It will get a little hotter only.

[vasko]

Where it is possible to take firmware for driver Mardus Kreutz

[kreutz]

Where it is possible to take firmware for driver Mardus Kreutz

PM me with your e-mail address, or go to Pminmo's site http://pminmo.com/ and look under Mardus-Kreutz.

[kreutz]

Guys;

I will be out of reach for the most part of the next 4 weeks. ON VACATION!!!
So far the assembly of the prototype boards is stopped due to my broken solder paste dispenser, I did not want to order a stencil just for a couple of prototypes.. .so, I ordered the parts to repair it and they will probably be here by Friday.

I will try to catch up on the weekend before leaving. I am sorry for the extra delay, I really need to rest for a while...

Thanks,

Kreutz.

[skullworks]

Dude, go clear your head. Enjoy!

[kreutz]

The parts needed to repair my solder paste dispenser came today.

[tiwanacote]

Have a beautifull vacations! enjoy!
Tiwanacote

[foxpt]

Nice artwork you make Kreutz!
Have a beautifull VACATION, enjoy !
Potential buyer here!

[Fish4Fun]

kreutz,

I am NOT a EE, but rather a long-time tinkerer. I am currently researching a driver very similar in specs to your design specs. In working with highly inductive loads and Mosfets in the past, I have used a TVS to clamp the reverse recovery and protect the Mosfets. I have found this method of clamping to be far easier to implement than more traditional snubbers. I am sure you have chosen not to use this method intentionally, I am just curious what the down-side to using a TVS clamp is.

Fish

[jeffs555]

Are you talking about "reverse recovery" or are you talking about clamping the reverse pulse caused by the collapsing field in the inductor? Reverse recovery is a characteristic of diodes, ie how long it takes them to go from conducting to non-conducting when the voltage is reversed. This can be a problem in bridge circuits, but I don't think that is what you are talking about.

If you are talking about clamping the flyback pulses, there is often no need for external clamps or snubbers for a bridge type drive using mosfets. Usually, the body diodes in the mosfets will clamp the pulses sufficiently. Also, many drivers use what is called synchronous rectification to reduce the power disipation in the diodes. Whenever a diode would be forward biased by flyback, that mosfet is turned on to eliminate the forward voltage drop in the diode.