BAF 2015 Coverage

[2 picoDumbs]

dunno

don't have neither greenies to spare (for them ) nor time .... or will

is that curse or luck - not needing more than regular FW wattage frame ........

Yeah, I understand.
I love the ACA, but this one has balls, plus decent damping factor, so I am curious to see whether it performs to my liking as I suspect it should.

After that I'm just going to focus on completing all my dumb amp ideas.

 

[generg]

Maybe it is worth to make a chain of 4 x 0R2 resistors and coming nearer to the critical value in two steps or even more.....

 

[2 picoDumbs]

Yeah certainly one way to attack it.
I'll wait till I have measured Id vs Vgs curves.

 

[2 picoDumbs]

Measuring up first device.
Biased to 1.4A at room temperature. Now I'm watching it rise with temperature. It's at 1.82A at the moment and still rising.
I'll give it an hour to reach equilibrium before taking measurements.

 

[generg]

Good luck!!!!!


the beasts look so harmless....

))

 

[2 picoDumbs]

The beast stabilised at 2.13 Amps (at Vgs=4.75V, Vds=20V)
I've increased Vgs to 4.80V, I'll go back and check it later (need to sleep)

I'll repeat later with Vds of 27V to 28V.

https://www.youtube.com/watch?v=ncFCdCjBqcE

 

[2 picoDumbs]

I'm starting to think a biasing thermistor (similar to F5) could be useful to help stabilise the bias on the bottom device.

 

[generg]

Yes, I am astonished how much the heat increases the current over the time.....

and "Step by Step", I saw it....

what happened in the elevator..... big step.....))

I hope the IXFN140 did not see this movie and will, when you take your sleep, make the big jump.....

 

[generg]

Hi 2picodumbs,

Is the part still alive.....))

 

[2 picoDumbs]

Hi 2picodumbs,

Is the part still alive.....))

Yeah it's still alive.
Not to worry though I have 10 in total.
Had to sleep, only got 2 hrs sleep the previous night. I'll try and do more today.

Just a side note. These things are really excellent at transferring heat.

 

[tordnilsson]

Maybe a silly question, but is there " thermalgrease" between transistor and heatzink ?

 

[2 picoDumbs]

Maybe a silly question, but is there " thermalgrease" between transistor and heatzink ?

I have tried both.
These things are electrically insulated so no need to worry.

 

[tordnilsson]

Well, I ask because I think it is very important to secure a safe " heattransport" with these high currents and power.

 

[2 picoDumbs]

Yep. People should do what ever they feel comfortable with.
Safety is important.

 

[Michael Rothacher]

The point of the thermal grease is to improve the contact between the part and the heatsink, probably a pretty good idea here.

 

[tordnilsson]

Just to be sure, I do not mean electrical insulation, I know that these transistors are insulated but I am always using a small amount of thermalgrease between component and heatzink just to be absolutley sure that maximum heattransport is secured.
Sometimes is "strange behavior" in components and circuits depending on insecure heattransport and instabil/unlinear temperature variations.

 

[Zen Mod]

isn't that conditio sine qua non , whenever we have two mating surfaces , both heat conductive ?

 

[2 picoDumbs]

The point of the thermal grease is to improve the contact between the part and the heatsink, probably a pretty good idea here.

It's never a bad idea except if it is too thick.

I tend to derive the best solution through experimentation based on real data.

 

[tordnilsson]

A thin layer, just some 0.1 to 0.5 mm thick. I have sometimes just put on a small drop and pressed the component and pushed it around a little bit just to get the grease on the whole surface of component.

 

[2 picoDumbs]

Yep