Help building a current booster

[chacedkirwan]

This is more of an electronics question than an arduino specific question, but I think the people here will be able to help me regardless. Plus, I want to incorporate arduino into this once I'm done.
I need help with a circuit I'm building. I created a version of this circuit that seemed to work before, but because of what seemed like bad connection I re-made it and now have a significantly larger issue.
I'm trying to build the Boosted Bidirectional Controlled Current Source in the LT1990's datasheet https://www.analog.com/media/en/technical-documentation/data-sheets/1990fb.pdf here. The issue is that my circuit does not follow the mathematical equation shown under the circuit and the current only seems to change when +V and -V are altered instead of the control voltage or sensitivity resistor. This is how I'm building it.

Here are the labeled and unlabeled versions of the circuit I made using tinkercad. To my knowledge, this should be correct compared to the diagram. If it's not, please let me know because the way I have it could be the problem.

Anyways, I continued to building it on a breadboard like this:

I'm only allowed to post 3 imbeds into this post, so I hipe this photo is good enough.I'm using 2N3904 and 2N3906 transistors.

This is the first problem I'm having, when I have the positive voltage come from the red and the negative from the yellow then the current is negative, which it shouldn't be. I know this can be solved by switching them, but I think that may be part of the problem because I have no idea why that could be the case. Part of why I know something is up with this is because the first time I made this circuit there was no problem having the voltages this way, which makes me think something is wrong with this version specifically.

When I do switch them, the current is not based on the relationship shown in the diagram. Using the resistor I am using (10 ohm) and the voltages I'm using (+2.5v, -2.5v, .1v), the only reason I can think of is that there are resistors in parallel somewhere that are lowering the current.

Please let me know if you have any input, or see something I did wrong, please help me out.

If you need any more information to help, please ask.

Thank you all!

[jremington]

The fritzing diagrams are very difficult to interpret, misleading and simply not useful. Please post a standard schematic diagram of the circuit.

[chacedkirwan]

if you want to see the schematic, I made it very clear that it is on the datasheet linked. Thank you

[jremington]

For help, post the schematic of YOUR circuit.

This, from the datasheet, bears little resemblance to the diagrams and photo presented above, which are uninterpretable.

Don't you agree that the schematic below is a very simple, easy to understand circuit?

In any case, do have fun with Arduino!

[EmilyJane]

post a schematic of your circuit if you want help.

[anon92864395]

Perhaps you could try this TinkerCAD feature
(I believe you are using tinkerCAD, but am not 100% sure)

(I know, it’s not exactly a good schematic, but it’s better.)

[EmilyJane]

OP's breadboard doesn't include a LT1990 rather it looks like they have tried to recreate one using a generic op-amp and a bunch of fixed and variable resistors.

Schematic required.

[JohnRob]

Your bread board has a bunch of resistors that aren't on the datasheet circuit. And your part layout is all over the place (not good).
Perhaps you should start with the exact same circuit as the datasheet, lay the parts out near each.
What are you V+ and V- values?

[PerryBebbington]

@chacedkirwan ,

I have moved your topic to general electronics, which is the category for general questions about electronics.