Can someone explain how the heated platform control on the Extruder board works?

[randyzimmer]

Can someone explain how the heated platform control on the Extruder
board works?
I see the Mighty Board has the same arrangement, a dedicated K
thermocouple and heater outlet for the tool head and a little wimpy
plug-in for the heated platform. Is that (thermister?) on the platform
also considered a K?
What I want to do is run a different heat sensor than the one on the
MBI platform and control a relay to power some big heaters on a big
heavy platform but still use the existing electronics of the Extruder
board.

[Jamie]

The HBP sensor is a RTD/Thermistor - I want to say Pt100, but I'm not sure.  The parts list for it on Thingaverse and/or the Makerbot site
should have the exact specs.

If you stick with that type of temp measurement even if the sensor is bigger, it should be easy to use the existing
controls - just have the 12V output that would normally go to the heater trigger a 12VDC relay.  If you want to use
a different sensor (Thermocouple) you might be out of luck and have to use a separate temperature controller.

Cheers

Jamie

[John D'Ausilio]

You can use the N-channel FET on the extruder board to drive a
P-channel FET as big as you want (switches + instead of -)
It's a bit tough to convert a positive coefficient thermocouple into a
negative coefficient thermistor .. might be easiest to do it with a
small pic and a thermistor conditioner

> --
> You received this message because you are subscribed to the Google Groups "MakerBot Operators" group.
> To post to this group, send email to make...@googlegroups.com.
> To unsubscribe from this group, send email to makerbot+u...@googlegroups.com.
> For more options, visit this group at http://groups.google.com/group/makerbot?hl=en.
>