Voltage Controlled Constant Current Source

[drago2187]

My project is to make a Voltage-Controlled Constant Current Source. I have found two solutions… This is first one

http://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=9018

Problem is last sentence: For the circuit shown, a maximum current of 20 mA is feasible for a maximum load of 1100 Ω. using higher-voltage op amps and larger power transistors can increase these values if cost isn't a concern.
Cost is not much of a problem, but obtaining those components is hard in Croatia. So that solution is out of the game!

Second solution is this one and I will try to make it work

http://www.priorartdatabase.com/IPCOM/000007013/

I am new in electronics and I need help with choosing components for this circuit. This is my basic problem

Specifications are: Ic is constant and max 100 mA, that current is controlled by U1 and U2. The load is variable from 0.5k to 2 kΩ. Second amp will provide constant current because it is connected like Current Source with Floating Load and first amp will provide control voltage.

Circuit works as it should in multisim file is hire

http://adria.fesb.hr/~dgabelic/VCCS.ms9

and the picture is in the attachment...

All help is more then welcome...

 

[berkeman]

My project is to make a Voltage-Controlled Constant Current Source. I have found two solutions… This is first one

http://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=9018

Problem is last sentence: For the circuit shown, a maximum current of 20 mA is feasible for a maximum load of 1100 Ω. using higher-voltage op amps and larger power transistors can increase these values if cost isn't a concern.
Cost is not much of a problem, but obtaining those components is hard in Croatia. So that solution is out of the game!

Second solution is this one and I will try to make it work

http://www.priorartdatabase.com/IPCOM/000007013/

I am new in electronics and I need help with choosing components for this circuit. This is my basic problem

Specifications are: Ic is constant and max 100 mA, that current is controlled by U1 and U2. The load is variable from 0.5k to 2 kΩ. Second amp will provide constant current because it is connected like Current Source with Floating Load and first amp will provide control voltage.

Circuit works as it should in multisim file is hire

http://adria.fesb.hr/~dgabelic/VCCS.ms9

and the picture is in the attachment...

All help is more then welcome...

Welcome to the PF. Coursework questions normally go in the Homework Help forums are of the PF, but for some projects, they can stay here in EE. I haven't decided yet whether to move this thread, but either way, you need to do the bulk of the work on it.

What is your main question exactly? If the simulation works, can't you just use the parts in the simulation, or is that whay you are saying that it is hard for you to get parts? What kind of opamps and transistors can you get?

 

[oswaler]

I would first commend you on your project to create a voltage-controlled constant current source. This type of circuit is commonly used in various applications, including electronic instrumentation and industrial automation.

Regarding the two solutions you have found, I would suggest that you carefully consider the limitations and advantages of each before making a decision. The first solution, using higher-voltage op amps and larger power transistors, may provide higher maximum current and load values, but as you mentioned, it may be difficult to obtain the necessary components in Croatia. In this case, you may need to consider alternative sources or adjust your project specifications to work with the available components.

The second solution, using the circuit from the prior art database, may be a more feasible option for you. However, as you mentioned, you are new to electronics and may need some help in choosing the appropriate components. In this case, I would recommend consulting with an experienced electronics engineer or seeking advice from online forums and resources.

When selecting components for this circuit, you will need to consider the specifications you listed: a constant current of 100 mA, a load range of 0.5k to 2 kΩ, and a voltage-controlled input. You will also need to consider the accuracy and stability of the components, as well as their cost and availability.

I would also suggest testing the circuit in a simulation program, such as Multisim, as you have already done. This will help you identify any potential issues or areas for improvement before building the circuit.

Overall, it is important to carefully consider your project specifications and the limitations of the available solutions before making a decision. With some research and help from experienced individuals, I am confident you will be able to successfully create a voltage-controlled constant current source for your project. Best of luck!