MOSFET Experiment

[sparkie21]

Great video, well explained. Thanks!

[AllAmericanFiveRadio]

Thanks sparkie21

[coxtube]

well done explained experiment, excellent video!!! :)

[AllAmericanFiveRadio]

Thanks coxtube

[asus3571]

great vid ? 4ya how important is cooling the mosfets on a motherboard

[AllAmericanFiveRadio]

Thanks asus3571

Keeping solid state cool is very important, the device must be within the temp range supplied by the manufacturer. Usually there is a limit as to how fast the temperature can change.

This was in the winter, in Michigan. An electronic computer telephone office was having problems because it was to hot in the equipment room. So some one opened up the outside doors to the equipment room and the office went down because it cold off to fast.

[asus3571]

@AllAmericanFiveRadio thanks lots reasone i was asking is because im into overclocking and wanted to know if place copper heatsins on all the mosfets of my board would be a good thing to do

[1957user]

So is that why a Heathkit VTVM has a switch on the probe to kick in the 1 meg resistor, to change from high to low impedance? And if so, why and when would you use the low impedance if the high is better? Now I understand that the low impedance meter draws more of a sample current as opposed to the high. Great!

Thanks (great video)

[1957user]

So is that why a Heathkit VTVM has a switch on the probe to kick in the 1 meg resistor, to change from high to low impedance? And if so, why and when would you use the low impedance if the high is better? Now I understand that the low impedance meter draws more of a sample current as opposed to the high. Great!

Thanks (great video)

[AllAmericanFiveRadio]

Thanks 1957user

Not sure. I would need to see the diagram of the HeathKit. It could be an active meter probe.

[3mustardMoNkEyS]

How different electrically are MOSFETs and JFETs? Or are they just different by internal construction?

And on the impedance multimeter testing, how'd the High Impedance meter still read 1.5+ Volts even after the voltage drop of the 33K resistor, did it just compensate for the resistance or what?

Thanks

[AllAmericanFiveRadio]

@3mustardMoNkEyS

There totally different.

I does not compensate. High impedance meters do not load down the circuit. Or another way to say it is that High impedance meters do not short out the circuit.

[MrHorsetail]

Rick, about how long will the gate stay charged to keep the mosfet turned on? Also, I have a irf630a and the data sheet says drain/source amperage is 9A @ 25c and 5.5A @ 100c. Is that ambient temperature, or the temperature of the surface of the transistor? I'd like to run a 6A motor @ 74F 25c. Would that work?

[AllAmericanFiveRadio]

Thanks MrHorsetail

The length of the charge depends on the CMOS and of course the the circuit it is in. You usually don't leave the gate open, I did it here so I could get maximum impedance.

Your circuit should work, but I would still use a Heatsink and a fan.

[man13preet]

explain please :

when it reaches high impedance, in order to switch it off, is it necessary to discharge the gate voltage or current?

price?

what is impedance?

uses and advantages?

[AllAmericanFiveRadio]

Yes. All transistors will need some kind of biasing. The biasing circuit depends on the type of transistor used and how you want the transistor to function.

From Radio Shack MOSFET IRF510 Transistor $1.99

Impedance, is the resistance, DC or AC, to electron flow. DC resistance is straight forward. AC resistance is frequency dependant. And you can have both at the same time.

High impedance will not load down what ever it is you are looking at. Low impedance shorts out the signal.

[IC742]

Very well explained, thanks for sharing the knowledge. Good Job !!

[AllAmericanFiveRadio]

Thanks!

[Wizard4592]

Very nice video, thanks.

[AllAmericanFiveRadio]

Thanks!

[Serpico261]

@AllAmericanFiveRadio

man ur just a genius, the way u explain things is just awesome. I teach sometimes electronics in school and as i saw this impedance vid, i thought, damn this is just a perfect idea, simple and clear!!

Thanks man!!

[AllAmericanFiveRadio]

Thanks.

I hope it helps.

[djbishop30189]

Clarity. I love it. Looking forward to your next videos. I have learned a lot.

[AllAmericanFiveRadio]

Thanks. That make me happy!

[ahonda55]

I am so thankful for you man, really i love this video, explains the point of low and high impdance very clearely.

Very good work.

Thanks a lot.

[AllAmericanFiveRadio]

Thanks. I thought about what to use for sometime. Had many ideas and some of them may work for future projects. Glad you liked the video and found it useful.

[Hammondlover2]

So theoretically, you could incorporate a MOSFET into an audio oscillator circuit in such a way that when the signal was stopped, the tone would fade away instead of stopping abruptly?

[AllAmericanFiveRadio]

Of course you would have to bias the MOSFET with in its range. MOSFET are voltage driven not current driven like junction transistors. So the biasing voltage for the MOSFET can be of a very high impedance.

[joernone]

Rick,

Once again, great demo and graphics.

Question: What 's the impedance of those two multimeters?

Thanks again.

Regards,

John

[AllAmericanFiveRadio]

Hey John,

The Simpson D.C. range is 20,000 ohms-per-volt. The Radio Shack is 10 meg-ohm.

Regards

Rick

[timjaz]

hi do u have any Schematics for the 2SA1943 i cant find any

[AllAmericanFiveRadio]

Try Google "2SA1943"

[AllAmericanFiveRadio]

I tried Googleing 2SA1943 audio circuit and found the Bee Power Amplifier MK II nanhifi May 2004. And some others too. Good luck.

[AllAmericanFiveRadio]

Try Google on this

"Super Class-A Amplifier Schematic with Toshiba 2SA1943 and 2SC5200"

I think this is what you are looking for.

[CoolDudeClem]

Very interesting and informative. I couldn't help noticing how similar to a tube it's circuit symbol looked. Is a MOSFET different to a FET, or is FET just a shortened name for it? If these were used in lets say an amplifier, would they be connected similar to how an ordinary NPN transistor would be?

[AllAmericanFiveRadio]

The Gate impedance is similar to a tube but MOSFETs can not handle the high voltage like a tube can. The Gate of a FET is not as high in impedance as a MOSFET. N-FETs are similar to NPN voltage requirements.

[jefferyb304]

It seems that a MOSFET could be used to like turn a Television on and off & ect . Am I correct ?

[AllAmericanFiveRadio]

They can be used almost everywhere. They are very a popular device

[rlewis1946]

Wonderful tutorial! Great teacher!!

RL Atlanta, GA USA

[AllAmericanFiveRadio]

Thanks.

[umajunkcollector]

jollly good show!

Thanks for a fine demo.

Don

[AllAmericanFiveRadio]

Thanks.