How Can I Develop an Adjustable Current Pulse Generator Circuit?

[kylecivicsi]

This is my first post, so a little background on me: I am a senior in EE at UofL, I am currently working for a company who has given me a larger project to complete (They kept me on part time while I finish school). I have not taken any analog or digital design classes, so I fear I am in over my head, so to speak.

One of the circuits I am working on takes an output from a uP, and converts it into a current puls over a pair of wires. The wires have a series of voltage pulses on them that is used to communicate to the uP, and the uP responds by inserting a current pulse during the 'low time' of the voltage pulses. The uP must be electrically isolated from the comm wires as well.

I am having trouble developing this circuit, as the current pulse must be adjustable from ~0-45mA and also from 0-40mS in duration. I have done some extensive google-ing and really have no idea where to start.

I suppose I was hoping one of you more experienced guys might have some ideas. Thanks in advance for any help you may be able to throw my way.

 

[stevenb]

This is my first post, so a little background on me: I am a senior in EE at UofL, I am currently working for a company who has given me a larger project to complete (They kept me on part time while I finish school). I have not taken any analog or digital design classes, so I fear I am in over my head, so to speak.

One of the circuits I am working on takes an output from a uP, and converts it into a current puls over a pair of wires. The wires have a series of voltage pulses on them that is used to communicate to the uP, and the uP responds by inserting a current pulse during the 'low time' of the voltage pulses. The uP must be electrically isolated from the comm wires as well.

I am having trouble developing this circuit, as the current pulse must be adjustable from ~0-45mA and also from 0-40mS in duration. I have done some extensive google-ing and really have no idea where to start.

I suppose I was hoping one of you more experienced guys might have some ideas. Thanks in advance for any help you may be able to throw my way.

Honestly, that sounds like too difficult a project to give a student that has not taken any digital or analog design classes. It's not clear why you are a senior and still have not taken at least a basic analog electronics class, but that is a side issue. Without even the basics, how are you expected to do this?

It would also be irresponsible for an experienced person to try and guide you over the internet. There are many questions an experienced person would ask about requirements and specifications, and going through a novice to translate is not likely to work efficiently, or at all.

You do have a good opportunity to learn something here, so I'm not recommending that you give up. However, somehow you need to work with an experienced person live, and preferably this experienced person should be at your company, since he/she will understand the full context of what you are doing.

There is one other thing you may want to consider. Possibly, this project may be a test situation that you are being placed in. Perhaps you will be judged on how you respond to difficult situations. If I were judging you I would hope to see you not give up, but I would also want to see you be honest about your present limitations. This basically means to seek help from the appropriate person with a positive attitude. See if you can find a guru in the company who responds well to compliments. Tell him/her you need some guidance from the "smartest, most creative and most experienced person available". But, be a little less obvious than that. Basically, do exactly what you tried to do in this post, but direct it at the right person. Later, once you have more information, you can direct some technical questions here, but make sure you are not releasing any proprietary information from your company.

 

[kylecivicsi]

Honestly, that sounds like too difficult a project to give a student that has not taken any digital or analog design classes. It's not clear why you are a senior and still have not taken at least a basic analog electronics class, but that is a side issue. Without even the basics, how are you expected to do this?

It would also be irresponsible for an experienced person to try and guide you over the internet. There are many questions an experienced person would ask about requirements and specifications, and going through a novice to translate is not likely to work efficiently, or at all.

You do have a good opportunity to learn something here, so I'm not recommending that you give up. However, somehow you need to work with an experienced person live, and preferably this experienced person should be at your company, since he/she will understand the full context of what you are doing.

There is one other thing you may want to consider. Possibly, this project may be a test situation that you are being placed in. Perhaps you will be judged on how you respond to difficult situations. If I were judging you I would hope to see you not give up, but I would also want to see you be honest about your present limitations. This basically means to seek help from the appropriate person with a positive attitude. See if you can find a guru in the company who responds well to compliments. Tell him/her you need some guidance from the "smartest, most creative and most experienced person available". But, be a little less obvious than that. Basically, do exactly what you tried to do in this post, but direct it at the right person. Later, once you have more information, you can direct some technical questions here, but make sure you are not releasing any proprietary information from your company.

Thank you for your response. There is only one other EE here (my manager obviously). I have no issues asking for his help (and do, all the time), the problem is that he is not the greatest at 'dumbing down' his ideas in a way that is understandable to me.

As far as the school work goes, I have taken a few analog analysis classes, but the issue is of course that those don't really teach you skills of building something from scratch. I'll save the rant on UofL's rediculous class structure though.

 

[schip666!]

I second the first reply...

But what is the difference between "Current" and "Voltage" pulses? Is the "current pulse" meant to be an analog signal? The description sounds sort of like I2C or SPI or other "modern" bidirectional serial buses, is there some new twist that is being developed?

For isolation, one usually uses an opto-coupler. But they are generally only for digital signals.