a couple of questions about add ons, fans, lights

i've tried to follow [hydraraptor.blogspot.co.uk]

to add the bed fan, but my melzi board looks different. where would i hook it up.

also . not sure i understand this sentence "
A plain MOSFET needs a series gate resistor to not exceed the maximum output current of the logic pin (and to prevent possible HF oscillation due source pin inductance),[...]"

as opposed to what? as opposed to the BTS134D that doesn't need that ?

_____

about the carriage add ons.
what goes in the two empty pins on the PCB marked PP? (is that the probe on wire 2? but it isn't used, is it)

also what happened to wire 8 ?

also, there are 14 wires coming in, and 15 pins, am i missing something ?

thanks

Edited 1 time(s). Last edit at 07/07/2014 01:53AM by avishalom@gmail.com.

There are CMOS logic-level-compatible MOSFETS that feature a built-in flywheel diode between Drain and Source.

These can be driven directly without the need for a series resistor although a pull-down resistor is advised to ensure the MOSFET is disabled until the microprocessor output is configured to drive a logic low level after reset.

Your Melzi should have a 10-way (2x5) pin header just above the USB connector (labelled JP16 on the circuit diagram). Pin 6 or pin 8 of this connector is usually used to drive the Bed Fan via the MOSFET.

Pin 8 of the 15-way D-type connector is not connected to the ribbon cable.

The two pins marked PP are intended for a Z Probe. One is connected to the thermistor ground. The other is currently unused and appears as a spare wire at the Melzi-end of the ribbon cable.

Regards,
Neil Darlow

Edited 1 time(s). Last edit at 07/07/2014 06:17AM by neildarlow.

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