Do current sources stack with current?

  • Thread starter Thread starter ainster31
  • Start date Start date
  • Tags Tags
    Current Sources
AI Thread Summary
The discussion centers on the implications of adding a 3A current source to a circuit and whether current sources can be stacked in series. It is clarified that ideal current sources cannot be placed in series without causing contradictions, as they are defined to provide a specific current. In real-world applications, current sources have a compliance range; exceeding this range results in non-ideal behavior, where the current output may drop to the lower rating of any stacked sources. The conversation also touches on the analogy of voltage sources, comparing them to gravitational potentials, but this analogy is met with confusion. Ultimately, real current sources behave differently than ideal ones, and stacking them can lead to unexpected results.
ainster31
Messages
158
Reaction score
1
Consider the following circuit:

h_1390408792_3749447_6c069ce658.png


Now imagine that I add a 3A current source:

h_1390408821_1096865_026c3809ba.png


Is the following equation correct? $$I_1=I_0+3$$
 
Engineering news on Phys.org
No, I1 is by definition 3 amps. You cannot put ideal current sources in series just as you cannot put ideal voltage sources in parallel. Doing either one causes a contradiction.
 
phinds said:
No, I1 is by definition 3 amps. You cannot put ideal current sources in series just as you cannot put ideal voltage sources in parallel. Doing either one causes a contradiction.

What would happen in real life if I did add the current source? Will the circuit explode? Or will it just become non-ideal? Will it convert from current source to voltage source? How do voltage sources and current sources even work?

If we use the analogy of comparing electric potentials to gravitational potentials, are voltage sources like ladders or slides?
 
ainster31 said:
What would happen in real life if I did add the current source? Will the circuit explode? Or will it just become non-ideal? Will it convert from current source to voltage source? How do voltage sources and current sources even work?

Real current sources have a range of voltage that can be applied across them and still work. This voltage range is often called the "compliance" range. If you try to operate a real current source outside of this range, it no longer is a constant current source, and usually will put out less than the intended current.

If you stack 2 current sources that have different current ratings, generally the higher current one will go out of compliance, and will output only the current that the lower current source is rated at. Thus, both current sources in series are passing the same (lower) current.

You can see this for youself -- look up common circuits for a current sink and a current source. Then stack the two schematics and figure out what will happen... (fun exercise) :smile:

If we use the analogy of comparing electric potentials to gravitational potentials, are voltage sources like ladders or slides?

Sorry, I have no idea what that means.
 
ainster31 said:
What would happen in real life if I did add the current source? Will the circuit explode? Or will it just become non-ideal?

In real life, current sources are NEVER ideal so the question you seem to be asking (what would happen if I put ideal current source in series) doesn't make sense. Berkeman has explained what will likely happen if you put real current sources in series.
 
I see the circuit posted as a current source in series with a voltage source. There is no reason that cannot be done.
 
Hi all I have some confusion about piezoelectrical sensors combination. If i have three acoustic piezoelectrical sensors (with same receive sensitivity in dB ref V/1uPa) placed at specific distance, these sensors receive acoustic signal from a sound source placed at far field distance (Plane Wave) and from broadside. I receive output of these sensors through individual preamplifiers, add them through hardware like summer circuit adder or in software after digitization and in this way got an...
I have recently moved into a new (rather ancient) house and had a few trips of my Residual Current breaker. I dug out my old Socket tester which tell me the three pins are correct. But then the Red warning light tells me my socket(s) fail the loop test. I never had this before but my last house had an overhead supply with no Earth from the company. The tester said "get this checked" and the man said the (high but not ridiculous) earth resistance was acceptable. I stuck a new copper earth...
Thread 'Electromagnet magnetic field issue'
Hi Guys We are a bunch a mechanical engineers trying to build a simple electromagnet. Our design is based on a very similar magnet. However, our version is about 10 times less magnetic and we are wondering why. Our coil has exactly same length, same number of layers and turns. What is possibly wrong? PIN and bracket are made of iron and are in electrical contact, exactly like the reference design. Any help will be appreciated. Thanks. edit: even same wire diameter and coil was wounded by a...
Back
Top