Hi
We are performing an experiment where we need a circuit to produce a constant current of 10mA for 30s followed by a sequence of 10 pulses of 5sec duration, each pulse being 400mA. The pulse separation is arbitrary.The pulses are applied to an experimental resistive device, which has a nonlinear time dependent resistance. We expect that the voltage drive needed might be about 100V but the higher we can design, the better. However we expect the voltage drive will be maximum 200V.
Please give me some tips on how to proceed on this problem
Regards

 

I remember you.
You never said beans about how the last project worked out.
Good luck with getting help with this project.

 

I think in the post http://forum.allaboutcircuits.com/showthread.php?t=11560 i already mentioned that the two circuits worked wonderfully and the project is still going on and i am still working on it.

 

Actually, you did. My apologies.

That was a very long, and frequently frustrating thread.

I'm not willing to go through those kinds of gyrations again.

So, if you are holding back anything regarding the specifications, you better post them now.

 

My previous post was a rather critical state in my employment and i was in a state of urgency. Now things are more relaxed. You may give me only the key tips, i will be more than happy to do detailing based on that so that your time and effort consumption is minimum . I think all the specs are provided, but since this project is to perform a research in a chemistry lab and which is being done for the first time , i estimate the voltage drive needed is minimum 100 and maximum 200. If you have any questions, please let me know. Please give only key points and let me go ahead with the detail.

 

So, your sample will never fall below 500 Ohms?

Is your sample capable of dissipating 80W?

 

We might assume that sample resistance will be less than 500 ohms.
The sample may degrade if it is subjected to high power, but we need to demonstrate something first and get the first version of data, even if its a degraded sample. If we get some data, we will then think of moving to second version to make it still better. So we may assume the power dissipation is possible upto 80W and Resistance<500 ohms.

 

Good luck with that.