How to measure “drain-source on resistance” in order to identify a fake MOSFET Transistor. Do this test for your MOSFET and compare it to the datasheet.
I used your method to test some MOSFETs and it made me look like a fool. The gate did not get fully turned on by touching drain and gate together. I complained about MOSFETs being defective because I calculated Rds without turning the gate on enough. One should run a separate wire from the power supply + to the gate lead (it should be at least 3v above power source voltage) while testing to get accurate Rds measurements.
Great info. One correction: The current will decrease slightly with each MOSFET in the circuit, thus the resistance calculations will end up slightly higher. You need to measure the current separately for each MOSFET and then apply Ohm's Law.
@@HighestRank No, there would be the same amount of meter reads for each measurement, so no more error by meter rounding would happen. I'm saying he needs to measure the amps for each separate MOSFET test instead of before any are in the circuit. It's still only one amperage reading per calculation just as before, only now it includes the actual current flowing with the MOSFET instead of the current without the MOSFET in series.
Both Drain current and Vds should be measured at the same time. The voltage drop Vds can affect the Drain current unless a constant current source is used.
Doesn't really matter - his numbers are spot on. I just tested some fake IRF540Ns myself with a milliohm meter and got .070 ohms Rds on. His results are good, even if you think his testing methodology is flawed.
The Source Drain resistance varie according to the voltage from the gate. You can found different value according to this. Minimal is 3,5, but if 20 volts are applied you can divide this resistance.
What you're saying is that the fake FETs are simply turning on too slowly, or that the real FETs are turning on too quickly, or that the fake FETs should have been tested at 3.5v for turn-on, or that the real FETs should have been fed 20v to see if they could handle the max. G-input regardless of low Rds.
Hi Electrical Projects, I just stumbled your channel and I have to say I'm really fascinated by your quick tutorials towards building miscellaneous electrical parts as a guide for someone like me who doens't know squat about such areas of composition. I'm just wondering how would you create a device for turning something on and off, and on and off again in a sequence at specific time intervals? And could you possibly create a video for such a device?
Hi, if you need to turn something on and off repeatedly you can just build something like "flip-flop flasher circuit", it is simple, it uses two transistors, you can add to it a relay and control anything... but if you need precise timings then you probably need Arduino, or if you need to turn something on/off at a specific time then you need ESP8266 to sync time from the internet. There are many videos with "flip-flop flashers" so I don't see a reason to make a video about it... but I want to build a device that after pressing a button turns a light bulb on for 10 - 500 seconds, and then turns it off.
@@ElectricalPro what if I'm trying to create something that mimic a person breathing? So inhaling and exhaling? It could take the form of a plastic bag and then something inside it that puts out air and suck air at specific time intervals to mimic an person's breathing pattern. Or even use a air pump putting out air for say 15 seconds and then turn off to allow the garbage bag with holes or something to release the contained air inside for 15 seconds. And right afterwards turn back on. How would it be done?
I don't know about mechanics, but the air pump will probably make a lot of noise. I only know electronics, not mechanics. Electrically you can control anything with a simple flip-flop circuit and relays... but if you need a delay between inhaling and exhaling, do it with Arduino. With Arduino, you can make it more realistic because you can add some randomness, and for example make some of the inhalings longer, or whatever you want.
Hi thanks for this video I have an hoverboard with a most problem and I didn't find a real one just a fake. Mine is IRF9530N and the one I did find is IRF9530 Did the fake is dangerous? and can she broke my hoverboard? Thanks❤
At the beginging [from0,25 to 0,32min.] when you show the fake and real mosfet, i noticed that on the fake one, the token IRF540N WAS WRITEN WITH GREATER NUMBER, O.K, so i concluded perhaps wrongly, that this point could drive someone that this will be the indice of the fake one. Now the question is .Is that notice correct and definit ? or not. I ask this in purpose to avoid the measurements. Thanks in advance ,i will apreciate your answer.
Another good test is to recognise the source... not as in source pin but supplier source. Pretty well 100% of devices coming from Ali, or Chinese Ebay sites especially those masquerading as local etc are fakes.. but from places like RS, Farnel etc... 100% genuine.
Hi could I ask for your help on something please could you explain batteries in series switching parallel so I could change on parallel and run something on a higher vote
Hi, I think it is because I've used 1.75A... but in the datasheet, they used 16A. On 3:18 you can see a line "Id = 16A" (If I understand it correctly). I've tried higher current ( about 6A) and got much closer specs to the datasheet. It seems that on-resistance changes depending on the current that flows through MOSFET.
because the specs on the datasheet are for 3,5v source, and you applied 12v. When the grid is overvolted, the RDS significantly decrease, and will be better.
hmm but I have borh! One a few fake ones and I ordered also an oryginal one to compare! When you look at it it is like you say but they work in very similar way!! I haven't noticed any difference! For me and for my purpose fake and oryginal are almost the same! The oryginal one came in a safer package and has slitely better parameteres and stability etc. but for someone who starts with electronics they would be the same! I am saying only about this MOSFET because it can happen also that the fake one is a totally crap as well...
I have power inverter that went bad, I suspect mosfets. Theres 4 of them IRFP260M. Do any other letters on it matter or not? I have P514J? Cant find exact mosfets, only IRFP260M part, other letters dont match. What else could be wrong with it if not mosfets. It powers on, shows voltage, says for a sec it uses 500w, then goes to 0. Cant power anything. I checked with multimeter the outlet, voltage is all over the place. No blown fuses. Maybe transistors? Nothing blown. Caps all good, connection to bluetooth shows all good. No alarms.
bad traces(water damage), shorted windings in the miniature transformers(overheating), dry electrolytics which simply have died quietly and poly-metallized caps which can no longer heal themselves. Last might be a current-sensing shunt circuit with a cold solder joint or open resistor. I suspect that any discrete semiconductor shorts would have by now smoked themselves and stained the circuit board and cooked any components in the local vicinity...
I have the same situation testing a pair (fake marks IR) IRFP4768 from china measuring at 1A Ids gives on state 4.5V but it should be 0.0015V Rds(on)=15mohm. It is obvious that chinese products are made on cheap production for real packing.
Is not kake but out of specification. Manufacter produce a large quantity. They make a sorting. Like sergio leone😂 the good, the bad and the ugly... The last makes injure for borf Thank you
I have bought IRF9610 some years ago, and are now using them in a design, these mosfets can dissipate 20 watts. However I have a test setup where the URF does drive a other mosfet and have a idle current of 10 mA and a voltage of 30 volts over it, calcaulating this make that the mosfet does dissipate 0.3 watts, normally I think even without a heatsink it can easely be save, however I did need a heatsink for it because it did get very hot without, so here, I can tell it is a fake mosfet, A shame Chinese supplyers does sell so much fakes I think we need to sanction that country. Oke you let see how we can see what is real, and that is the type with solder on connections, and copper is visible on the sides of the mosfet metal for cooling. Regards.
There is a good chance to buy fake on aliexpress, I don't know about ebay. I bought mine in a local store. Try to find a store that buys MOSFETs directly from the manufacturer.
I tested a mosfet IRF3205 from China eBay and the result is 120 mVolt VDS , Ids 3.55A Rds 35mohm Vgs 12 v same results with other original bought from my local dealer... The datasheet 8 mohm for mine MOSFET IRF3205 is with very high pulsed current. Read all datasheet. Rds does not constant.... Change with Vgs current Vds... It is not so easy to measure...
PLEASE HELP ME ): I have a double battery ups and it's two MOSFETs are gone, It's because when i give too much load on my ups . And these are the MOSFETs prnt.sc/qwhbyd . Please tell me how can i change them Or If i buy any of irf3205 mosfet it's going to work or not ,,,,, prnt.sc/qwhfey
I brought 47N60C3 mosfets from China. They had Korea on some of them. Average source drain resistance 2.4 - 4 OHM no bull. I hope the Chinese find and execute such people, they are not worth the dust they are made off. Owe, they worked powering halogen bulbs but inductive circuit seem to fail in "on position"- much cursing! God - throw the cursing on their heads!
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