Custom (very) Quark esc heatsink... - Page 6 - RC-Monster Forums

BrianG · 04.08.2007, 10:08 PM

Yeah, I've never thermaled before I added any extra sinking, but I thought it got too warm for my liking. I guess I'm just funny that way. :)

BTW: What's up CHC. Haven't seen you around a lot lately...

coolhandcountry · 04.08.2007, 10:18 PM

I think some times the driving styles effect the heat issues as well.

Not alot brian. Just figured i would show up and throw some input around. :D

BrianG · 04.08.2007, 10:43 PM

Quote:

Originally Posted by coolhandcountry

I think some times the driving styles effect the heat issues as well.

Not alot brian. Just figured i would show up and throw some input around. :D

I think you're right about the driving style. Of course, there are a ton of other factors as well.

While you're throwing input around, make sure it doesn't hit anyone. Someone can lose an eye that way! ;)

BrianG · 04.08.2007, 11:36 PM

The whole switching thing is a double edged sword. Too low and the motor speed suffers (not to mention erratic behavior). Too high and you have more losses due to having more switching pulses. By the sounds of it, they are actually decreasing the slew rate, which should cause things to heat up more. I'd be very interested to see how they do that! The only way I can see it working is if they use a tracking power supply, which I don't think is feasible/practical at anything close to the frequencies they are talking about.

I have no idea what kind of motor they have in mind. Personally, I think the motors we have now are pretty darn good since they approach 90% efficiency.

Just to clear things up; I'm not an electrical engineer, just someone with perhaps a less-than-healthy interest in this stuff. :)

Serum · 02:28 AM

I think he means slew rate.

The time it takes to activate a FET, and also important, the ripple it brings along in the signal.

'A transistor is a digital piece of hardware'

I don't think you get the basics of a transistor. because a transistor/FET is a analog as possible. that's what's causing the slew-rate. it's not an on/off operated thing. there are million steps in between.

Serum · 04.09.2007, 02:37 AM

another thing;

if it has got a 10W heat dissipation, and it's 96% efficient, the input power is 240W, a bl controller is more efficient than that.

zeropointbug · 04:01 AM

10 watts, no one said it was definitively 10 watts. The heat dissipation is totally dependent on power usage, does anyone have an EPA for RC MT? :005: :005:

So what is a transistor in half ON then? :032: A millions steps in between?

Serum · 04:39 AM

I missed the 'average' in the 10W part.

Since when is half on considered digital? if ON is close to 0 of internal resistance, and off is close to endless internal resistance, what is digital about that? The slewrate thing explains itself this way.
depending on the speed the signal is put on (and the speed of the transistor/fet) is one of the things that makes the controller more efficient.

Serum · 04.09.2007, 05:04 AM

perhaps it's not clear to you what this rise delay means;

The speed of a FET/Transistor isn't endless fast. Nor is it's steering signal. (not to mention the polution of the steering signal), this steering signal is obviously is needed to put a fett into full conduction. It simple takes time before the near 0 ohm (full conduction) status is reached. In this time, the FET isn't on it's ideal internal resistance, but the load (motor) stays the same. the fet is at highest efficiency at full conduction. During this 'travel' to full conduction it produces heat (since the internal reistance is getting smaller and smaller reaching full conduction). The speed in which a signal is able to rise, is explained in volts per micro seccond (slew-rate) This rising is done with a steering signal, this steering signal can not be perfect. once the rice took place on a short amount of time, there always is something as a sinus on top of the block-wave, (it's quite impossible to make perfect block-wave) you need the feedback from the signal to correct the errors in the blockwave. (this is the steering signal) not to mention the far from ideal load of a motor (induction) since a controller works on PWM, it's all about different lengths of 'blockwaves'

Now, decide for yourself; if a transistor was digital, would there be a lost? (digital is 0 and 1, and NOTHING in between, since a FET basicly is analog, you have got losses in switching it ON/OFF (1/0)

Hope this explains.

zeropointbug · 04.09.2007, 12:53 PM

MAybe 'digital' is a tittle much, but it can't really be called analog either though. Everything in this world takes time, that includes transistor switching, so, that does not necessarily make it analog because of this.
You know what I mean?

zeropointbug · 04.10.2007, 06:50 PM

Well i got the Arctic Silver adhesive in today, and went to my machinist, but he doesn't stock copper... bummer. So i am using aluminum instead, should work great still, might run a few degrees warmer though.

I'll post some more pics when I get the piece cut, and pasted on.

zeropointbug · 04.10.2007, 11:07 PM

Here is the results. Let me tell you, it was a tight fit! I should have lapped down the thickness of the alum. pad a little bit, the case ends were tight fit to go it, and the programming button was tight into the button pad (you might be able to see it in the pic. But i did a quick test running it on the table, the Quark gets a little very quickly unlike before where it took a while.... then I popped it onto the big heatsink and instantly was chilled back down to room temp.

I have a feeling this setup will work beautifully! ;)

Stay tuned, I am going to tap the copper heatspreader on the heatsink and use 3mm screws with the CF plate to secure the Quark down with pressure.

Serum · 04.09.2007, 01:00 PM

that's not the point right now; do YOU know what I mean?

zeropointbug · 04.09.2007, 01:26 PM

ya i know what you mean. That aspect of the FET is somewhat out of our control is it not?

Just thought of this.... how about a Quantum FET?! :005:

A FET utilizing Quantum Mechanical effects such as entanglement (non-locality), superposition! Who knows maybe we will have the perfect FET someday soon, zero switch on time, room-temp super-conducting... :017:

GriffinRU · 01:33 PM

Quote:

Originally Posted by Serum

that's not the point right now; do YOU know what I mean?

Rene, you are the man!

Zeropointbug, this little bit cost efficiency. And if you spent some time reading about FET's and how it works, then maybe you change your view point on digital and analog. Otherwise it is pointless even talking about any efficiency problems inside ESC...