An electronic component that sources current - if it sinks current it is called a current sink but both devices (sinks and sources) can be called sources. An IDEAL current source will supply current , maintain high voltage compliance (i.e. adapt it's output voltage to match the network it is ...

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1answer
15 views

Nodal analysis independent and dependent voltage source and current source

After spending quite a few hours I am stumped with this problem while trying to solve for Vo, which is supposed to 0.5V and this was confirmed through PSpice. I have no idea what I am doing wrong or ...
2
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2answers
44 views

Superposition principle: Dependent sources treated as independent sources

Since I began studying, I was taught that when analysing a circuit using multiple sources, independent sources could be turned off, meaning that I could transform a voltage source into a short, and a ...
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1answer
26 views

Find four current mesh

I have to find the 4 current mesh in this circuit V1= 12V R1= 1/12Ω R2= 1Ω R3= 1/3Ω I1= 6A R4= 1/3Ω R5= 1/2Ω R6= 1/13Ω I2= 6A I tried a source transformation and got this I3= 144V R1-2= ...
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1answer
32 views

Current Controlled Output Using PWM

I am looking to control a proportional valve with a PWM signal that will correlate into exact current amounts (for example a 25% duty cycle will output 200mA, and a 90% duty cycle will produce let's ...
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1answer
23 views

Cadence, BSIM3V3, and the Body Effect

I am trying to meet the compliance/min output voltage of a wide swing current mirror so the output current (10uA) is within .1% or +/- .01uA. I am using Cadence and ami06 nFET's to do so. I am always ...
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1answer
24 views

Special Source Transformations

I'm not sure if this was asked already, but I could not find it when I searched. We're learning about source transformations, and while reading my textbook I came across this: and in the following ...
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0answers
63 views

Need better linear control over input for current sink cirucit. - new [closed]

I hope someone can help me this time, maybe this is more info. I have a circuit that has the analog input 0-5V controlling a 0-3A current sink circuit. See attached. I need to have control from "0" ...
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1answer
48 views

What Formality Am I Using To Isolate This Portion Of The Circuit?

If I have this circuit in which the switch opens at t = 0 (after being closed for an infinite time, making the circuit steady state), for which I'm trying to find the voltage across R2 as a function ...
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6answers
306 views

Is there any physical device called current source?

I have seen both current source and voltage source in many electrical circuits (in paper). When it comes real hardware battery can be considered as a voltage source. Then what is a current source ? ...
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1answer
33 views

Which options exist for switching the polarity of an output with low leakage?

In my application, I want to switch the polarity of an output which supplies a controlled current up to 50mA (accuracy 100uA + 1%) at up to 36V. The current sensor is on the low side of the output. ...
0
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2answers
65 views

Switching current source ~1 μA — how to switch off quickly?

I would like to have a precision current source ~1 μA loaded by a resistor ~100k and a voltage source. Also I would like to switch on and off the current. The problem is that when the transistor ...
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1answer
57 views

How do you find the equivalent voltage of the current source in this circuit? [duplicate]

The circuit is shown at this schematic. How do I find the equivalent voltage of the current source by simplifying the circuit?
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2answers
99 views

Equivalent circuit?

Can I simplify this circuit to just one resistor? How can I find the equivalent voltage of the current source in this circuit?
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1answer
65 views

Understanding 74LVC245 datasheet and current source/sink

I'm using a SN74LVC245A (datasheet) to shift 5V TTL down to 3.3V so I can read the signals with a Raspberry Pi. However I am getting really weird results (a 60Hz input signal is picked up by the Pi ...
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3answers
165 views

Maintaining a constant current with varying loads

I've designed a constant current source using a current mirror, we need an output of about 50mA. The problem is that we build it and heat has become a problem.The transistors and the R_load are both ...
2
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2answers
80 views

Howland Current Pump VS Wilson Current Mirror

I am interested on knowing what would be a better solution to create a current source for low current applications (below 20mA), an opamp based current source such as a Howland current pump (link to ...
7
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4answers
460 views

Choosing resistor values for non-inverting amplifier and why?

The gain here is A = -Rf/Rin. However, lets say I want a gain of 10 V/V. Which resistor value would you choose and why? I know that you could have infinite number of combinations for these ...
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1answer
61 views

How can I model a variable current sink in spice?

For a project I am working on (related question here) I need to model a nonideal variable current sink in spice. Simply reversing the orientation of a current source or inverting its value is not ...
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1answer
35 views

How do I increase (multiply) the value of a current sink?

I have been shown an IC that is a current sink PWM dimmable LED regulator. It happens to be a WS2811. While this works well for low drive currents (up to about 20mA), I was approached with the idea of ...
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3answers
112 views

Constant Current Source circuit improvisation

simulate this circuit – Schematic created using CircuitLab I was wondering whether I could use this circuit as a constant current source provided my load circuit impedance was less than ...
2
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3answers
146 views

How to make a constant current source

I don't understand current sources! Batteries are voltage sources, but how does one actually implement a current source? I was looking at current mirrors to see how they work, and I understand the ...
0
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1answer
48 views

Bipolar Transistor PTAT Cell and setup

I am in a measurement systems class at school, and we have a project to design a measurement system. I was reading my text book when a diagram caught my fancy, and I thought I would try to build it. ...
1
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1answer
90 views

Can't figure out voltage-controlled current sources

I'm trying to teach myself how to wire circuits, but I don't know if I got the correct answer for this? Where is a good place for me to learn the order of operations for solving circuits? Thanks.
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0answers
29 views

Split common resistance to input and output port

I have a circuit like this. simulate this circuit – Schematic created using CircuitLab I need to represent R1 in both input and output side so that R1 can be removed from the circuit. I ...
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3answers
101 views

op-amp replacement

I am trying to built this current source, but he LM107 seems to be discontinued, what opamp could I replace it with? I dont know much about opamps and there are so many choices. Any maybe an opinion ...
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1answer
59 views

How can the differential pair have individual common mode gain?

If you think of a better title, please do edit or let me know to edit, but this is how I thought I could word the question. I am finding difficulty in understanding how a differential pair exactly ...
0
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2answers
110 views

voltage source vs. current source

I am just not sure that why in development labs, current sources are not as popular as voltage sources. I have worked in different places, and they all have been using voltage sources. I just want ...
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1answer
47 views

Finding the thevenin resistance

The task is to find the thevenin equivalent (seen form terminals a and b) of the following circuit: I believe I have found the thevenin voltage by simply finding the voltage drop over the 5 ohm ...
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4answers
255 views

Charging phone battery with a high current source

I am working on a project which the goal is using some android tablets to show pieces of video file to form a multiscreen. One electronic problem that I have faced is: The tablets should be always ...
2
votes
2answers
138 views

Single current source with parallel loads for many RTD sensors

I'm trying to build a circuit that contains multiple 3-wire RTD PT100 sensors (12 of them). I have a microcontroller with plenty of ADC pins so I could potentially measure the RTD and the wire ...
2
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3answers
195 views

How do you drive a high current load from a moderate current source?

If I have a power supply that can supply 5A @ 12V and I need to be able to supply an inductive load with 20+A @ 12V, how would I go about this? I need a burst of current for about 2-5 seconds. Will ...
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2answers
90 views

What defines a source of power, the current or the voltage?

I have an apparently simple question, but I can't seem to figure it out. I learned in school that the generators (source powers) are defined by their voltage, and that made a lot of sense to me. ...
2
votes
2answers
120 views

Consistent LED intensity from low and variable voltage supply

I want to light 1 red LED among 3 (or no LED at all; never 2 or 3 simultaneously), using 3 output ports of a micro-controller (PIC18LFxxx or so). The catch is that I'm operating from a low and ...
2
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3answers
205 views

Steady State RLC Circuit With Dependent Current source

I'm trying to figure out the reason why in the following circuit, at steady state, the current ix is zero. My best guess is that because there is a parallel branch which by KCL should equal 100ix and ...
2
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2answers
134 views

FET - Source follower utilizing current source to lower voltage offset

I understand that if I use a FET as a source follower, the signal will be slightly attenuated due to the fact that there is some small inherent resistance in the FET, creating a voltage divider effect ...
1
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2answers
119 views

Advice for my Voltage controlled Amplifier

In class we are designing a VCA together as part of a bigger circuit. The aim is that we have an input of speech and an input of music and when we speak the the music reduces in volume. The speech ...
1
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1answer
81 views

Humming Sound of UPS vs DSP Inverter

I have a APC 1000VA BR Smart UPS.I have noted that the UPS Produces a Humming Sound when running on Battery Power.But my older a normal 500VA UPS(not from APC) seems to produce far lesser humming.The ...
2
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1answer
102 views

Calculating voltage in RLC circuit

Well I think the prof has made a mistake in one of his exercises, though asking here to be sure, The question is to calculate the supply voltage in the system below. simulate this circuit ...
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1answer
65 views

What if there's current INTO an output pin?

maybe my question is easy to answer and maybe I shouldn't have asked it, but I'm really not sure. I would like to connect an XBee ZigBee module (3.3 V) to a microcontroller (PIC, 5V) using the ...
4
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2answers
166 views

Bidirectional Current Source

I'm trying to design a bidirectional current source for the purpose of measuring very small (0.0001 Ohm) resistances. I've come across this circuit: I can see that the transistors are there to ...
0
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2answers
63 views

Current and voltage sources

What happens when a current source is connected in series with a voltage source? I mean to ask, what will the current be through the series combination and voltage across it? Is it allowed to make ...
1
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1answer
135 views

Very Simple Discrete Current Source

I'm trying to work out why someone would choose the right circuit over the left one. The only thing I can think of is, that one on the right can be made an adjustable current source by making \$R1\$ ...
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1answer
282 views

Source Transformation of dependent sources

Would it be correct to use use source transformation on a dependent source. For example, would it be legal to turn a voltage dependent voltage source in series with a resistor, into a voltage ...
1
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0answers
67 views

Equivalent Resistance

I'm working on the following homework problem. (Yes, this is homework. :p ) I'm supposed to find the current through L1 as a function of time. simulate this circuit – Schematic created ...
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3answers
169 views

Does current source affect flow of current in circuit with a variable resistor?

Suppose you have a current source in series with a resistor R the current through the R resistor would be the current generated by the current source. How would the current through the circuit change ...
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3answers
246 views

Are there any way to get (75V 1A) output from 78V input

Is there any way to get 75 V 1 A output from 78 V input? I found the TL783 high voltage adjustable regulator. But this can supply only 700mA output current. I had forgot to tell the details. Main ...
0
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1answer
68 views

Current source and resistor

If i have a current source and a resistor in parallel, i will have two nodes,if i ground the the node which faces in the direction of current of the current source will all the current flow to the ...
2
votes
2answers
159 views

How do I quantitatively describe a system with 2 parallel diodes and a current source

What would happen in this system? How can I find the bias point of a circuit like this: Considering the LEDs are not perfectly matched. The 35mA are generated by a high precision stablizied current ...
3
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1answer
254 views

How to wire the REF200 IC for a 100uA current output?

I am trying to create a 100uA constant current source to power a homemade sensor. I bought a few REF200 ICs http://www.ti.com/lit/ds/sbvs020/sbvs020.pdf since each has two 100uA current sources. ...
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2answers
270 views

Input Resistance: Why can you ignore current sources?

This may be a weird question, but I simply can't figure out, why you can entirely ignore current sources when calculating the input resistance of circuits. Here is an example (it's actually a ...