Interesting new product from @Watterott_electronic ; a flyback diode package for stepper motor outputs - Protects the driver from transient voltage spikes due to motor induction. What are your thoughts on this little board?
Originally shared by Watterott electronic
New product - SilentStepStick Protector
The SilentStepStick Protector is an addon module for StepStick and Pololu A4988 compatible stepper motor drivers. The board provides flyback diodes (freewheeling diodes) for the motor outputs, so that they are also protected against induction voltages in the unpowered state of the driver.
It’s for those moments when you really need to push your axis around without actually jogging it. And for that, it’s probably going to do a good job of keeping your driver alive.
However, i think that if you’re smart enough to put a protective board like this in your printer, you’re probably also smart enough to not push your axis around that much.
Then again, at half the cost of a new driver, it’s a tough buy if you consider it “insurance”.
Hmm, I’d see it as an excellent additional part in a “new user kit printer” just for the added insurance factor. At 5eu a pop, it wouldn’t change the overall price of the kit too much. And would eliminate user error for those who don’t know to not push the printer platform around while the printer is off. (this includes curious parents and siblings and small children)
Are TMC2100s more susceptible to this than other drivers? I push around my carriages all the time with 4988s, 4982s, 8825s, and 6128s and never have any issues. As long as some passive consumer such as an LCD backlight or always-on fan is connected to use up the power being generated by the motors, the voltage shouldn’t rise enough to hurt anything.
Plus, the driver’s H-bridge ALREADY HAS flyback diodes built into it via the MOSFET body diodes. For example, the 8825 datasheet shows them in schematics (check pages 11 and 13 of http://www.ti.com/lit/ds/symlink/drv8825.pdf).
I guess this could be useful if you plan on unplugging your motors while the printer is running. But I’m not an EE, maybe I’m missing something.
I had no idea that moving the unpowered axis posed a danger to the drivers. Apparently, some high speeds are necessary to damage the driver, because I’ve never had driver problems, and haven’t been shy about pushing things around. Not really throwing things around, but moderate shoving.
I’ve moved axis’ quite quickly on our Deltas, and never blew anything up. I was able to move them quickly enough and long enough to have the raspberry pi that was attached to the azteeg boot up fully.
I use TMC2100s and I move my X and Y before every print to spread oil for my bushings. I haven’t killed a driver yet. But, I’ll probably buy them anyway because I like the speed of moving by hand.
@Ryan_Carlyle yes, every driver already has them internally, but they are also only body diodes, which are by far not as good as dedicated Schottky diodes.
We made some tests, how to get the TMC2100 drivers broken.
If you have a motor supply voltage above about 20V and if the supply voltage is disconnected when the motor is in motion then the drivers can be damaged very quickly.
@ThantiK just given me a great idea, old stepper motor, 3D printed handle, few diodes caps and a regulator to make a hand cranked raspberry pi!
Back OT, I’d welcome more protection built into the step stick or on a board with soldered drivers, but am not worried enough to buy them as an add on!
@Thomas_Sanladerer I am with you on the Schottkys being better. But I’m not convinced the body diodes are inadequate, except for extreme abuse scenarios. The driver chip manufacturers don’t recommend adding additional diodes or include them in the reference implementation schematics. They’re probably good to have, but I don’t see enough justification for the price OR the added failure points of the stacked sockets.
Frankly, if you’re unplugging wiring while the printer is running, my (harsh) opinion is that you SHOULD have your board damaged. It’s a valuable lesson in not doing dumb stuff with live electronics. Given the serious danger of loose wiring in heater/thermistor circuits, I’d say it’s a net win for a newbie to fry a $10 driver if he learns a valuable lesson and doesn’t burn his house down later.
