SissySIT

[pras1170]

I think that you need to mount THF-51S on some heatsink...

Radiating aluminum, right?

aluminum

I'm mimicking it. I haven't had electricity

Tomorrow, I will take out a piece of radiated aluminum at home and put it under the thf-51s, so it will be high

So are these pictures right?

Which other places need to be modified

 

[Ben Mah]

i have mesured my pair of TH51s and at 18V VDS i have one at 850ma for -1.92V gate bias and the other at 950ma

is it ok for the project ?

Unfortunately, ZM is "off the grid" (see post #262) but if you look at post #81, he says that anything between "-1 to -3V6 is adequate for SissySIT circuit".

Your measurements are slightly below the -1V, but close. ZM's post says that he will be away until Saturday, so hopefully he will be able to answer your question then.

 

[pras1170]

YES ang NO？

Unfortunately, ZM is "off the grid" (see post #262) but if you look at post #81, he says that anything between "-1 to -3V6 is adequate for SissySIT circuit".

Your measurements are slightly below the -1V, but close. ZM's post says that he will be away until Saturday, so hopefully he will be able to answer your question then.

Select 10V voltmeter
1 turn the 10V voltmeter with the pot to full 9V

2 now switch on power supply and turn the pot that the voltage goes down from 9V slowly

3 watch the ampere meter, when see 2A, stopp turning the pot and look at the 10V meter what ist the value….maybe 5V or 3V or 2V….or ……the SITs are all very different°

4. you write the value of voltmeter on the SIT or in a list… Or….

 

[Ben Mah]

Sounds right. When power supply is on and pot is to full 9V, current should be 0A. As 9v is reduced, current should increase from 0A, and yes, you write the value of Vgs when I=2A.

There will be different values of Vgs for different SITs. Since the 9V negative terminal is connected to the gate through the pot and 1K resistor and the positive terminal is connected to ground, Vgs is actually considered to be a negative value.

 

[juanitox]

Unfortunately, ZM is "off the grid" (see post #262) but if you look at post #81, he says that anything between "-1 to -3V6 is adequate for SissySIT circuit".

Your measurements are slightly below the -1V, but close. ZM's post says that he will be away until Saturday, so hopefully he will be able to answer your question then.

i have made new try with a stronger power supply and i get with -2.4V gate bias
1.83A with the first and 1.93A with the other so mine are not really matched

 

[generg]

You do not have two DMM (digital multi meter)!at your working place instead of the simple volt and ampere meters?

This is the material I prepared (the experiment has not officially started yet, because the voltmeter has a problem, it stays there all the time and does not return to zero. I will buy another voltmeter tomorrow to replace it) : according to # 81
Everybody take a look at it for me, right?
I have not turned on the power, everything is imitation state, has not officially plugged in power
Let's take a look. Is that right?

5 a current meter
9 v battery
10 v voltage meter

1 w 1 k resistor
10 k locator
24 v power supply
24V dc fan

 

[Ben Mah]

Watanabetomoaki has replied with an answer:

"The written numbers on them means Id (A), at Vds=25V Vgs=-1V aroun 25 degreeC."

As I mentioned in an earlier post, I have two THF-51Ss from watanabetomoaki that have 2.5 written on them. When I tested them at 24V and 1.8A, I measured Vgs of -4.46V and -3.54V respectively.

I just measured the one with Vgs = -4.46V again but with Vds 25V and Id = 2.5A to try to mimic watanabetomoaki's parameters. The result was Vgs= -4.28V.

Lowering Vgs even more raises Id even more, so I cannot replicate the Vds=25V, Vgs=-1V, Id=2.5A.

I wonder about the capacity of his power supply? Can it produce more than 2.5A? If it cannot, that is probably a good thing as testing at Vgs=-1V does not seem like a safe way to grade the devices.

I am in discussions with him and I have mentioned that testing at Vgs = -1V may not be a good thing.

 

[Ben Mah]

i have made new try with a stronger power supply and i get with -2.4V gate bias
1.83A with the first and 1.93A with the other so mine are not really matched

I should learn to read properly. I misread your earlier post that mentioned 850ma and 950ma, and 1.92V. In my mind I saw 850mV and 950mV, and 1.92A, and thus my erroneous comment regarding them being close to -1V.

Old age is scrambling my brain and eyesight.

 

[pras1170]

You do not have two DMM (digital multi meter)!at your working place instead of the simple volt and ampere meters?

This experiment was taken out of my shop by me, and I worked in the shop during the day, with less comprehensive tools

We'll do what we said yesterday, test it, and then publish the results

I don't have time to take it out and test it. I have time in the afternoon

 

[generg]

This experiment was taken out of my shop by me, and I worked in the shop during the day, with less comprehensive tools

We'll do what we said yesterday, test it, and then publish the results

I don't have time to take it out and test it. I have time in the afternoon

I understand pras1170, good success!

 

[pras1170]

Please take a look, I am right? Please take a look at the test process;
THF-51T OLD USED
THF-51S NEW NOS 2SK182ES NEW NOS

 

[pras1170]

The radiator forgot to pick up a radiator at home today
I put it at the door of my home last night, but I forgot to bring it when I went to work in the morning

Please forgive me

 

[pras1170]

old used THF-51T

The radiator forgot to pick up a radiator at home today
I put it at the door of my home last night, but I forgot to bring it when I went to work in the morning

Please forgive me

 

[pras1170]

Please help to see if this test is correct or wrong

 

[pras1170]

for THF51-S , body is drain ( no need for isolation for test , just keep heatsink electrically from other voltage potentials , other than + rail), fat protruding pin is source,while thin protruding pin is gate



again , any power N channel JFet , having ebough cojones , and having gate voltage in range of -1 to -3V6 is adequate for SissySIT circuit

if you sort your P channel mosfets , and use those with highish gate voltage (for -19 to -25V and Iq 1A8 to 2A) , in area of -4V5 , JFet can have even -4V gate voltage for intended conditions
have more questions , shoot

Copy the language of Zen Mod

And having gate voltage in range of -1 to -3V6 is adequate for SissySIT circuit

Did I do that?

 

[pras1170]

I can't see everyone's opinions, I can only go to sleep, see you tomorrow.

 

[generg]

I think you did well....!

Thank you, now you can form pairs for us!

And I see you use a DMM now for the gate voltage.

 

[juanitox]

pardonnez moi mon ami, i don't think mesuring at a VDS of 9V is correct for the
ZM amp , i thought it would be 19V VDS at 1.8A ..

but please use an heatsink or a piece of thick metal under your VFET

 

[pras1170]

pardonnez moi mon ami, i don't think mesuring at a VDS of 9V is correct for the
ZM amp , i thought it would be 19V VDS at 1.8A ..

but please use an heatsink or a piece of thick metal under your VFET

The battery is 9V, but the voltage can only be 9V. The drawing information I saw looks like this, I don't know if it is correct

 

[Ben Mah]

It looks correct to me. As generg stated, you are using the DMM for the gate voltage. That can be seen in one picture where it is displaying -9.00V, and then you lower it until 2A is shown on your ammeter.