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1answer
87 views

High side current sensing

I want to sense 30 amps of current using op amp in high side. I know that there are many dedicated current sensing amplifiers for this purpose. But I'd like to try it with an op amp. I have tried high ...
0
votes
1answer
27 views

What is the predictable difference of the voltage drop between the V+ and V- lines on a shunt resistor?

I am making an electronic speed controller, and the half-bridge driver I am using has a built-in overcurrent protection feature. In order to utilize this feature, I have to supply the pin (a ...
0
votes
0answers
43 views

micro controller cant able to sense analog value (ADC input) from op amp output

I am trying to sense the current in my motor controller using shunt resistor and an op amp. Opp amp amplifies the voltage drop of the shunt resistor, multi meter shows the output voltage good. But ...
2
votes
2answers
83 views

Full wave rectification by opamp

I am trying to read a current waveform from a shunt resistor series with the power line. Using a full bridge rectifier, I got the following waveform: The waveform was sampled every 2 millisecond ...
6
votes
3answers
647 views

Current sense amplifier + op-amp buffer + ADC: Measuring down to 0 with a single supply

I'm thinking about current sensing with a high dynamic range (10 mA - 20 A) and using LTC6102 as a high-side current sense amp (the voltage would be 54.6 V max, a 13S6P Li-ion battery). ...
3
votes
2answers
1k views

Current measurement op-amp calculation

I am trying to measure the current using sense resistor method. Low Side Current Sensing method: I am using shunt resistor in the low side, there will be a voltage drop across the resistor. Since ...
1
vote
1answer
108 views

How does this Current Comparator Circuit Work?

I have a quick couple of questions about this circuit: The schottky diodes are obviously for minimizing slew delay but how exactly do they do this? If the non inverting input is tied to ground and ...
0
votes
2answers
166 views

Overcurrent Sensing

I am designing an overcurrent protection circuit. I am sensing current with a LEM sensor across a sensing resistor of 16.5 ohm. The voltage drop for maximum current is 2 V. In the next stage I am ...
4
votes
2answers
2k views

Simple Op-Amp setup for current sense has a strange working range

I am using a LM358D dual amplifier at the moment and my goal is to measure over-current on 2 motors. Before I'll be doing that, I made a test setup to test the equations and check the output signal of ...
0
votes
1answer
90 views

How to use a CT to measure overcurrent?

I plan to use a CT to measure the current on a resistor whose voltage will be controlled by two SCRs in antiparallel. The main function of the CT is to detect an overcurrent in the system to proceed ...
5
votes
4answers
1k views

High side current sensing with LM358

Basically I want to measure high side current through a 1 Ohm shunt with this configuration: The circuit works perfectly in a simulation. However on a bench it doesn't produce any meaningful output. ...
0
votes
2answers
163 views

How to choose current sense resistor and current sense Amplifier for precision sensing

While measuring current from 0A to 500mA with 10uA step, I am using current resistor, current sense amplifier, 16-bit ADC.How do I choose current sense amplifier and current sense resistor
1
vote
1answer
152 views

Use Raspberry Pi to power a low noise inverting amplifier with negative voltage input

I am looking to use a Raspberry Pi to power and read the current from a current-to-voltage converter. I am currently using two batteries to power the operational amplifier, as shown in the schematic ...
0
votes
3answers
127 views

Differential amplifier op amp problem

I am learning Differential amplifier, and it has been fun and smooth, but I encounter a problem here. This is a 10x Differential Amplifier setup, and the voltage drop across R5 (0.01 ohm) is 5mv, so ...
1
vote
2answers
228 views

op amp DC gain drop

I got a really simple circuit, it is a voltage follower in cascade with an inverting amplifier. The input of the voltage follower is a current to voltage converter, measuring nanoamperes with a 1 M ...
1
vote
1answer
810 views

How to I calculate max current draw for this circuit?

I’m trying to calculate the max current pulled from my 15V and -15V supplies. My OPAMPS also use the supplies for current. All of my numbers seem really whack. The part I am most confused about is ...
0
votes
0answers
123 views

High side current sensing in BLDC motor?

I want to measure DC current flow through the 48 V battery in bldc motor (through Inverter circuit). Are INA 282, INA 169 work properly or not? Since my battery motor specification is 48 V, 5 Amp, 250 ...
0
votes
1answer
149 views

Measuring forward and reverse current on a photodiode

I'm in need of a different perspective here on how to approach the circuit I'm designing. Currently I have a PD that I want to reverse bias with 2V and measure the current from the PD. This is easy ...
0
votes
1answer
65 views

Simple BrainTeaser: Running an AC current between two independent amplifiers

I'm working on a project using an ultrasound method for identifying objects in water. For example, such a device could be used to locate bodies on the floor of an ocean bed after a plane crash. Our ...
0
votes
1answer
302 views

Differential op amp to measure negative current flow through shunt (Rails set to 0 and 5v)

Note* I have done some searching and though there are related topics to this one, this one is unique and I think it warrants its own Question, especially as asking additional questions on another ...
2
votes
0answers
467 views

Improved Howland Current Source not providing less than 1mA

I've learning a lot about op amps and constant current sources lately. I've implemented the above Improved Howland VCCS. Found it on page 6 of TI's "A Comprehensive Study of the Howland Current Pump": ...
0
votes
1answer
641 views

Current Measure on 230V 50Hz

I want to make a power meter which I can plug in a electrical socket in my house. I tried around with falstad to measure the current over a shunt and came up with this solution. But the problem is ...
0
votes
1answer
119 views

Why does an op-amp in this simulation not produce a large voltage swing?

One circuit I have seen used many times is an op-amp and a current sense resistor to implement overcurrent protection. I have seen this circuit implement both an overcurrent protection that turns off ...
0
votes
0answers
676 views

calculating current draw for opamp circuit

I am trying to understand how to estimate the current drawn by the following opamp circuit and how much current the regulators for the +14/-14 rails should be able to deliver. The opamp used is the ...
-1
votes
2answers
292 views

Instrument Amplifier (AD623) incorrect (too low) and inconsistent gain

I'm getting an incorrect and inconsisten gain from an AD623 instrument amplifier. The datasheet states that RG = 100 kΩ/(G − 1) where RG is the resistor between pins 1 and 8 and G is gain. My R3 is ...
1
vote
0answers
54 views

differential amplifier measuring current below supply rail

I am measuring the current from a battery (12v) using a shunt resistor. But if i can i want to use the normal rail as supply for the op-amp: Now my thinking is that because of the two voltage-...
1
vote
2answers
385 views

A question on current sensing through a very low resistor

I'm trying to sense the current through a wire, and so far I decided to use a 1mOhm shunt resistor to convert it to voltage. As you see in the below circuit, the current source I1 sources 6A amplitude ...
0
votes
3answers
2k views

OP-AMP circuit for voltage to current conversion

It is required to design a circuit for voltage to current converter to have a current output with 4-20mA. So, I wonder if the above circuit will work. Suppose that the input ranges from 1 to 5V.
3
votes
2answers
344 views

Which circuit is better? (Op Amp Question)

These circuits are for sub pA current detection. Each circuit has the same gain, however; shouldn't the multistage amplifier be theoretically be faster than the single stage gain? TINA TI simulations ...
0
votes
1answer
367 views

Transresistance amplifier and current measuring

I was studying some shunt voltage amplifiers, and I came out with this circuit. R2 is for input voltage offset compensation only, and is the same value as R1. simulate this circuit – Schematic ...
0
votes
2answers
258 views

Is there an amplifier voltage limit for the input signal even if the differential voltage is small?

I am building a simple current sensor. The amp says the maximum differential voltage is 5V. I'm not getting more than 1V in differential voltage at the moment. Is it safe to test differential ...
0
votes
2answers
407 views

Op-amp with constant gain for small signal(mV)

simulate this circuit – Schematic created using CircuitLab I want to measure current using shunt resistor and I want to amplify the voltage over the shunt using an op-amp. The shunt resistor ...
0
votes
2answers
269 views

Non invasive Method to measure if there is any current in a line

We have a project where we have to measure if there is any current through the a cable, but having not common ground and knowing that the current could come direct or reverse direction. We thought ...
0
votes
0answers
619 views

Current Sensor Difference Amplifier

I am trying to use this equation for difference amplifier to sense a max current of 75 mA. However in my circuit I have no R4 so which equation should I use?
1
vote
0answers
626 views

How to calculate total current drawn by a circuit

I have been trying a make simple alarm using LM324 and a buzzer. The circuit is pretty simple. I need to power it from my 9V/1000mAH battery. But here is the part am stuck. I don't know how to ...
0
votes
1answer
134 views

Current Sensor Callibration

I want to measure a low current (from 0 to 75mA) using the attached schemtaic for ACS712. The ACS712 sensitivity is 185mv and I want to use the max gain of 47 to input vout to a microcontroller(0-...
1
vote
1answer
275 views

How to measure the current delivered to the load by a high voltage (>50 V) non-inverting op amp amplifier?

I would like to measure the current delivered to an arbitrary load by a non-inverting op amp amplifier. Key information for this amplifier and design goals: The output voltage swing is high (up to ...
3
votes
2answers
390 views

Define input current of Op-Amp

I haven't done and studies in Op-Amp category yet but I watched a (trusted) video on Youtube and one thing is not quite logical as the next sentence: "No current flows in or out of the inputs of ...
3
votes
3answers
460 views

500V unity gain buffer

I am currently in the process of designing a high-voltage bias supply for use with an ionization chamber. The voltage source itself is taken care of however I need a unity buffer to drive the guard of ...
0
votes
2answers
1k views

Current Sensing with Non-Inverting Amplifier

Hello, I'm implementing a current sensing circuit as shown in the schematic. The simulation works but the physical circuit does not. On the breadboard if I measure between the shunt and the load to ...
0
votes
1answer
195 views

Measuring current transducer output - differential or single ended?

I'm designing a front-end for an ADC that will be measuring the voltage of a hall effect current transducer. I have been reading up on differential vs single-ended measurement, and have become a bit ...
3
votes
1answer
1k views

Current Sensing with Differential Amplifier

Hello, I have to use this circuit as part of a school project so I'm limited to this design and these components. The voltage regulator works as anticipated however the differential amplifier does not....
0
votes
1answer
386 views

Confused how to derive output voltage from Op Amp and RC circuit

So I'm trying to solve the following question: I'm very confused how they derived the equation for the output voltage. It was from my understanding that for an ideal op amp, the current through the ...
1
vote
1answer
2k views

Difference between shunt resistant measurement circuits using op amps

I've been trying to measure the current going through a motor controller and basically succeeded in obtaining the same values from two different circuit configurations: simulate this circuit – ...
2
votes
1answer
446 views

Automatic ranging current sensing

I am trying to implement a current shunt sensing circuit. This should be automatic and currently i want it to measure uA to around 200mA, and Change to the mA range at around 200uA. This is to profile ...
1
vote
2answers
740 views

OP amp circuit — current measuring

My hardware design team have given me circuit to measure current consumed by load.I have to measure current consumed by Load using MCU ADC. Can someone explain what exactly this OP amp is doing ? I ...
2
votes
1answer
1k views

How does this circuit read 4-20mA current loop input through Op-amps?

I am a software guy working on coding a control system on a board whose hardware designers are all gone. While i have got everything else working, there is one piece (a 4-20 mA current loop ...
1
vote
2answers
1k views

Increase sensitivity of an op-amp

Firstly, I'm not sure if sensitivity is the correct term, if anyone has a better suggestion please feel free to edit the title So I have a motor and I want to measure the current output which I'm ...
2
votes
1answer
1k views

Current sense circuit for 0.1uA to 100mA dynamic range [duplicate]

For a battery powered sensor node, I need to be able to measure current levels that have a dynamic range from 0.1uA [standby current] to 100mA [peak current]. For this, I am thinking of a high-side ...
2
votes
4answers
2k views

Low-side current sensing

I'm trying to build a brushless dc motor driver, which provides the possibility to measure the currents on all three phases of the motor independently. The driver IC that I'm using (DRV8313) has three ...