Flyback diode on sanguinololu heated bed control board.

Hey everyone.

I started getting uncomfortable with the mosfet and traces running my heat-bed on my Sanguinololu. So I made a small relay board to do the heavy lifting.
I have a couple of questions however.
I did a good hour long print last night. As expected it clicked on and off during heating. I checked my mosfet at the end of the print and it was cool to the touch, YAY.

I've read a bit about others that have made these, and it appears that people are using flyback diodes to protect the sanguinololu.

I've had people tell me that all the heating components are protected, and other say, the sanguinololu isn't protected.

Does anyone know on the 1.3a rev. or would you advise that I put a flyback diode in the circuit?

Is the only real risk the corrosion of my switch contacts (mechanical relay)?

If I do put a diode in place, will it cause the heater to stay on longer than necessary?


Thanks in advance!

-Mike




.

Flyback diodes have no influence as long as current is flowing. They mean to carry away current generated when coils are turned off. As a heated bed is no coil, they have nothing to do at all.

Nice you re-invented the SevenSwitch

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Thanks Traumflug!

I actually added one on the relay coil circuit just for safety.

I think I need to spend more time on the WIKI - LOL
The SevenSwitch uses a more pretty design and of course a MOSFET so no click-clack.
I'm going over your build guide now, for education!

Though I do enjoy re-inventing the wheel!

Thanks Again,
-Mike