Slightly puzzled.

A microcontroller output pin is wired through a 4k7 resistor to the
gate of an N-channel MOSFET (BUK477 or MTP3055).

The MOSFET source is grounded.

The MOSFET drain is connected to a 220R resistor, then a red LED, then
to 5V.

The micro is running PWM, at 1kHz, with a very small duty cycle.

My question; why does the drain voltage rise briefly as the gate
rises?  Why does it not rise if the LED is shorted?

http://dev.laptop.org/~quozl/DS1Z_QuickPrint105.png (with LED)
http://dev.laptop.org/~quozl/DS1Z_QuickPrint104.png (with LED shorted)

Legend;

- yellow is micro output,

- cyan is gate,

- purple is drain,

- blue is 5V nearby.

Circuit is on socketed breadboard with 70mm hookups.

--=20
James Cameron
http://quozl.netrek.org/
--=20
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