Almost all the stuff is easy to build. I have to admit I learned a few things following and helping with it, and will be doing some experiments of my own eventually.

My experience is you don't smell toasted transistors, but the smell of burning flesh as you touch them is very distinctive.

 

It is true that i made changes in the data. I have obtained two circuits from you and three from another forum and i am going to test all five. I am highly thankful for your time and patience but it is very important that the lab keeps running so i am going to try every possible input that i received.
THANKS once again

 

I am sorry but i was nervous as my instruments were malfunctioning and we lose research funding in such cases.

Are all those who assisted you, in every forum, getting an "honorarium" or a fellowship for their efforts?

 

I've posted this one before, it requires a regulated power supply. A darlington would work better though. R1 set the total range.

Another way of doing it...

Thx a lot

 

I've posted this one before, it requires a regulated power supply. A darlington would work better though. R1 set the total range.

Another way of doing it...

Wendy's second circuit, the one using the three terminal voltage regulator, is an excellent choice that I have used in a wonderfully successful product 20 years ago. The regulated current was set to 100mA and it was rock stable. But for constant use there does need to be adequate heat sinking for the regulator. And it is important to have a reasonable source voltage.