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Old 06-09-2004, 02:37 PM   #16
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Default FETs

Those numbers do look good. I'm not sure about the difference between Silicon and Package Limited. It could be the configuration of the FET. If you notice in the diagram that that particular transistor can be configured to stand up or lay down. I do know that the Novak GT7 uses a lay down type transistor. It is in the TO-262 package. Alot of people think that it uses SMTs because of it's size. Maybe the lay down configuration can't handle as much current or heat as the stand up type. I'm not an expert on this subject, but several months ago I was looking for answers like you are and nobody would help. I started taking my ESCs apart and looking up the specs myself. When you are looking at the On-Resistance (ohms) rating of a transistor it is usually given at a 25 degree celsius (room temp.) rating. Most people don't realize that when the temp. goes up the efficiency and current handling go down.
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Old 06-09-2004, 02:43 PM   #17
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Quote:
Originally posted by SalvadoriRacing
yep...

it's the first cyclone.....the brake mosfets are damaged.....the brake simply stopped working.....

I hope he's using a Schottky diode on all of his motors. According to Novak burning up the brake FETs is usually caused by not using one. I recently installed the Novak Schottky module on my Cyclone '99 to make sure that doesn't happen to me. I took the 14 gauge wire off of it and soldered it inline on my motor leads about 1 inch from the motor. That makes changing and working on motors alot better and it's out of the way.
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Old 06-09-2004, 03:22 PM   #18
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thanks a lot tmeek.....


i'll try to find further informations about this mosfet.....
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Old 06-09-2004, 03:48 PM   #19
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The package limited number refers to the amount of current that can be run in the small pieces of metal that enter the device. So in other words, the silicon can handle 280 amps at 25 degrees C, but the package can't pass that much current. The GT7 does lay the FET's down, but it still has to pass the current through a small wire instead of two pieces of small wire. In my case I changed the FET;s in my Duster so that I could run hotter mod motors. Now I need to change the brake FET's because they get really hot.
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Old 06-09-2004, 05:03 PM   #20
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Default FETs

What soldering process did you use to change the transistors? Did you make any other changes to the ESC? Thanks for any info!
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Old 06-09-2004, 05:26 PM   #21
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thanks kufman!

so do you think the IRF2804 FETs will work greatly in my G9 both for forward and braka FETs??????
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Old 06-09-2004, 08:16 PM   #22
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I used a desoldering gun to remove the FET's. I don't have one, but where I work does and they don't mind me using stuff as long as I do it on my time.

Who make the G9? Is that a tekin or something? I haven't presonally tried the 2804's , but the numbers indicate that they would probably work well for both drive and break FET's.

I have to warn anyone that tries this procedure that you may kill the ESC with the heat from taking out the old FET's. I got lucky and I tried it first with a cheap speed control. If you do try it, be sure to buy the proper FET package. Old style ESC's use to-220 style FET's, where newer ESC's use D2pak or surface mount parts.

Have fun and good luck.
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Old 06-09-2004, 08:19 PM   #23
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yep....

it was made by tekin....

i have a friend who repairs ESC since 90's.....

he told me that here in Brazil he can get mosfets that drain more than 120 amps.....

this is why I'm searching for the FETs in USA......
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Old 06-10-2004, 10:14 AM   #24
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Default FETs

To tell you the truth it's not all about a high amperage rating. Manufacturers may pick a transistor that will handle 80 amps, but when they connect 6 of them parallel it gives a total rating of 480 amps. As most tech guys will tell you the numbers given for ESCs aren't "real world" numbers. 480 amps for more than a second or two would probably torch even the best ESCs. The numbers are usually inflated to increase sales. I've been told by tech support that when using 6 cells the most current draw you can expect to see might be 100 or so amps. That would be for a very short time though, maybe 1 second or less. Having a high current rating for that split second may be helpful if you have a sudden current draw, such as a shorted armature (which I had over the weekend). I'll give you one example of when having less is OK. I have a Tekin G-10 "Pro" ESC. The IRF7413 FETs are only rated for 13 amps of continuous current, but Tekin uses 20 of them on one board. This would give a total rating of 260 amps. This may not sound like alot compared to other ESCs, but that ESC feels like it has a higher power output than any other ESC that I've ever owned. The surge rating for that ESC would be around 1160 amps, but I doubt that I'll ever be running that much power. Hope this helps!
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Old 06-10-2004, 12:12 PM   #25
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my g9 has 9 mosfet......5 forward and 4 brake......

the resistance is 0,0007 ohms......

with the IRF2804 FETs the resistance goes down to 0,000459 ohms.....maybe 0,0004 , because I don't know is the mosfet resistance is 2,3mOhm or 2.0mOhm (the website shows 2.3 but the datasheet shows 2.0).....
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Old 06-10-2004, 02:25 PM   #26
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A .0007 on-resistance is really good even by today's standards. The G9, G-12cIII, Cyclones and many other ESCs are still capable of winning on any level. The G9 is setup exactly like my G-12cIII. According to the picture on the back of the box (G-12cIII without the case) there are 5 drive FETs (400 amp minimum rating ) and 3 brake FETs (120 amp minimum rating) and the single FET is a 6 volt, 5 amp BEC. Does the G9 work great? I have heard really good things about it. If you really want to change the transistors then go for it. Good luck and be careful!
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Old 06-10-2004, 02:54 PM   #27
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my g9 works well.....

i thought the single fet was a brake mosfet as well....

i've noticed a slightly advantage on the newest escs like the quantum and the gt7, this is why i'll try to make some mods on my speed insteado of purchase a new one.....
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