Multi function tester TC-1

[djmiyta]

I got one of these recently. Problem is I don't know if any of the information is really relevant to me and pedal building.

I was hoping someone could help me decipher the readings I get from the tester then trying to compare that info to the data sheets but I'm really just pissing in the wind cause I don't understand what I'm looking at.

So for the hell of it I threw a bunch of mmbfj201 in the tester and wrote down the results two examples are below

Idss = 0.10mA Idss = 2.0mA
Id = 0.21mA Id = .73
@vg = 146mV @vg =503
Id = ,0.00 Id = 0.00
@vg = 591mV @vg = 1.11v

When I look at a datasheet I cannot find these parameters to compare to and really don't know what exactly I'm to compare. Anybody here able to school me in some of this or point me int the direction with a link ? I would really appreciate it.

 

[Cybercow]

Unfortunately, the TC-1 does not measure the Vgs(Off) parameter, which is one of the key parameters for JFETs.
J201s typically have a Vgs(Off) value of between -0.3V to -1.5V
Most of what I've encountered range between -0.65V and -1.20V

I use a Peak Atlas DCA75 for testing.

 

[djmiyta]

Thank you for the reply . Just to be clear the info I get from the multi tester is basically useless? I mean for matching Jfets and finding out other parameters of transistors and Jfets?

And yeah when I got this the DCA 75 was a bit too pricey for me hopefully sometime in the future

 

[Cybercow]

Thank you for the reply . Just to be clear the info I get from the multi tester is basically useless? I mean for matching Jfets and finding out other parameters of transistors and Jfets?

And yeah when I got this the DCA 75 was a bit too pricey for me hopefully sometime in the future

For JFETs, the TC-1 is insufficient IMO. The DCA75 is an excellent tool that displays all the needed parameters. But at ~200 zorkmids, it is a pricey tool.

GeoFex has an article for testing FETs.

And this circuit may also provide a far less expensive means of testing . . . .
(The readings I got from these were within about 10% when compared with DCA75 results,

 

[djmiyta]

Just finished working that exact one up. Hopefully you are able to answer a couple more questions
1 - For the Vp measurement it says to negate reading to obtain actual Vp. I'm unclear as to what that means
and
2 - reading x 10 to obtain actual IDss in mA does that mean whatever value I get gets multiplied by 10?

thanks again for the response

 

[Giorfida]

For JFETs, the TC-1 is insufficient IMO. The DCA75 is an excellent tool that displays all the needed parameters. But at ~200 zorkmids, it is a pricey tool.

GeoFex has an article for testing FETs.

And this circuit may also provide a far less expensive means of testing . . . .
(The readings I got from these were within about 10% when compared with DCA75 results,



View attachment 72963

That’s how I sorted my j201 for the Ultimatum build… also the inspiration to fork out the $$ for the DCA75

 

[Cybercow]

Just finished working that exact one up. Hopefully you are able to answer a couple more questions
1 - For the Vp measurement it says to negate reading to obtain actual Vp. I'm unclear as to what that means

To "negate the reading means to simply put a negative sign/symbol in front to it. Most NPN JFETs have a negative Vgs(Off) value.

2 - reading x 10 to obtain actual IDss in mA does that mean whatever value I get gets multiplied by 10?

TBH, I've never bothered with IDss values -unless they are outside of spec for the specific JFET.

 

[Feral Feline]

I got one of these recently. Problem is I don't know if any of the information is really relevant to me and pedal building.

I was hoping someone could help me decipher the readings I get from the tester then trying to compare that info to the data sheets but I'm really just pissing in the wind cause I don't understand what I'm looking at.

So for the hell of it I threw a bunch of mmbfj201 in the tester and wrote down the results two examples are below

Idss = 0.10mA Idss = 2.0mA
Id = 0.21mA Id = .73
@vg = 146mV @vg =503
Id = ,0.00 Id = 0.00
@vg = 591mV @vg = 1.11v

When I look at a datasheet I cannot find these parameters to compare to and really don't know what exactly I'm to compare. Anybody here able to school me in some of this or point me int the direction with a link ? I would really appreciate it.

Interesting.

The OP shows the two examples clumped together and hard to read, but when I quoted the OP it showed in the quote...
The examples are well-spaced apart, but...
revert back to clumped together when I post the reply.
A quirk of the forum software.



For anyone not aware, you can make tables in your posts.

Click on the vertical stack of 3 dots to the far right in the legend...



After clicking on the square mini-table icon, you can select the number of boxes you want by dragging your cursor down to as many rows as you need and across to get columns.

	MMBFJ201 #1	MMBFJ201 #2
IDSS mA	0.10	2.0
ID mA	0.21	0.73
@VG mV	146	503
ID	0.00	0.00
@VG mV	591	1110

Editing the table: while making or editing your post you can add rows or columns or delete rows or columns by clicking on the table.