Hi,
I am using Nmos IRFZ44N and STP36NF06L as a switch, opening and closing a c ircuit with 5 volts power suply, a 82R resistor and two Red Leds in paralle l. But, I can't undestand why when I use it physically, with gate connected to ground (i.e. OV in the gate) the voltage drops are:
-OV in the resistor (Obviously, no current driving)
-10mV at the LED
-3.6 V from drain to source (which is connected to ground)
Where are the other 1.4V???
Any point will be welcome.
Thanks.
circuit with 5 volts power suply, a 82R resistor and two Red Leds in parallel. But, I can't undestand why when I use it physically, with gate connected to ground (i.e. OV in the gate) the voltage drops are:
Your voltmeter draws a small amount of current, so in order to measure the drain voltage, the LED has to be forward biased a little. Try measuring from the positive supply downward instead.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Or to put it another way, the node where the source and LED cathode come together in floating when the FET is off, and will float wherever the voltmeter pulls it.
-- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
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