Go Down

Topic: Transistors in parallel (Read 14120 times) previous topic - next topic

tomasi

Hi again.
dc42, a friend of mine gave away a dozen of these FETS. But I agree that logic level FETS are way better.Bought some logic FETs RFP30N06LE on sparkfun . Lets see what happens.
I put resistors as Grumpy Mike warned, and made a simulation. Here it is:



I will make a PCB today and test if everything works.Still confused about RDS(on) triode zones, saturation and stuff. Time and burnt fingers will teach. :)

cheers.

Grumpy_Mike

Quote
I put resistors as Grumpy Mike warned,

Better but you are still missing a base current limiting resistor for Q2. Put it between the collector of Q1 and the base of Q2.

What is C2 doing? It will cause the FET to be in the linear mode and so it will dissipate more power than if it was just used to switch.

dc42

#32
Nov 27, 2011, 06:56 pm Last Edit: Nov 27, 2011, 06:58 pm by dc42 Reason: 1
R2 is not needed, it is in parallel with R4. R3 is not needed either, provided R5 and Q1 are near the Arduino pin and not likely to pick up noise before the Arduino finishes running setup() . Aim for 10v or a little more at the gate of the FET, e.g. make R1 and R4 equal (1k each will do) to get about 14v. As Mike says, you don't want C2, and you need a resistor (10K will do) in series with the collector of Q1.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

GoForSmoke

You guys read metal better than I read code!

1) http://gammon.com.au/blink  <-- tasking Arduino 1-2-3
2) http://gammon.com.au/serial <-- techniques howto
3) http://gammon.com.au/interrupts
Your sketch can sense ongoing process events in time.
Your sketch can make events to control it over time.

Go Up