Questions tagged [constant-current]

Questions regarding Constant Current supplies, devices and applications. As opposed to Constant Voltage supplies. Voltage will vary while Current remains the same. Common in LED lighting applications.

Filter by
Sorted by
Tagged with
0
votes
1answer
53 views

Understanding constant current source in amplifier stage

I am teaching myself electronics in my spare time and I am trying to look at circuits and understand how they work. I am currently studying amplification and transistor basics, and I have started ...
0
votes
1answer
78 views

Constant current limiting circuit

Can someone help me understand the working of this circuit: My questions : Please explain me how this circuit will work in its entire operation range. I am not able to understand the purpose of the ...
0
votes
2answers
55 views

Constant current LED driver using transistors

I have this circuit: I understood the operation: On power-up Q1 and Q2 are off. There is no collector current so L1 is off. If the digital control input on the left is brought high (5 V) Q1 will ...
1
vote
1answer
102 views

Working of the below Op-amp circuit

I have seen this circuit at my workplace and I'm trying to understand the working and the purpose of each component in the below schematic. I also happen to note that this was a constant current ...
2
votes
2answers
56 views

Choosing an appropriate constant current LED driver

I am trying to replace a (suspected) constant current LED driver in a plant lamp as it has a terrible plastics smell. I am searching for a more high quality driver. I do not know then forward voltage ...
0
votes
0answers
45 views

2 N-MOSFETs in series

I'm trying to design a circuit to charge a capacitor bank with constant (limited) current and then discharge the capacitors through an LED. I've come up with the circuit in the schematic below, ...
1
vote
1answer
78 views

Driving RGB LED with Constant Current Driver - Only Blue Working

I am driving a common anode RGB LED using a 15mA constant current LED driver. What really confuses me, is that only the blue light works when plugged in. The red and green ones seem to be dead. ...
0
votes
1answer
116 views

Driving 36V LED from 12V Supply

I have a chip-on-board LED that requires 36V max, 300 mA, but I have a power supply designed for a 12V max, 900 mA LED. The power supply is a pretty standard constant current power supply that ...
1
vote
0answers
45 views

Constant current MOSFET circuit oscillating, how to get it to stop? [duplicate]

simulate this circuit – Schematic created using CircuitLab I have a constant current load circuit using a sense resistor and discrete quad op-amp set up as a 3 op-amp instrumentation amplifier ...
1
vote
0answers
29 views

Step up in series with step down DC DC and led driving

I'm having an issue that I can't seem to resolve. I have 100 watts rgb leds that I'm driving with constant current drivers (https://www.amazon.com/gp/product/B019W4C5IE/ref=...
1
vote
1answer
65 views

Lead acid battery charging @ 0.2C

I am charging a 26 Ah battery with a solar charge controller. The battery's manufacturer recommends charging with 0.1C. Which charges the battery at 2.6A during bulk mode. That is what I was going to ...
1
vote
1answer
48 views

How to make a constant current-pulse current charger for lithium ion?

I've been doing some research about battery charging system with the CC-PC-CV (constant current-pulse current-constant voltage) method. However I have some questions and need some guidelines for ...
1
vote
1answer
45 views

Constant current driver and undervoltage protection for lipos

I'm searching for a way to drive a couple LEDs with a single-cell LiPo battery, such that the LEDs will be cut off completely when the LiPo voltage drops below, say, 3.3V. PCB space, component count ...
1
vote
3answers
83 views

Is it possible to design a linear voltage regulator which delivers constant current but adjustable output voltage?

Is it possible to deliver a linear voltage regulator with the following specficiations: input reference voltage is from 0.8V to 1.4V output voltage has to follow the input reference voltage, it is ...
1
vote
1answer
63 views

Understanding Thermal Characteristics for Microchip CL2N3-G Constant Current LED Driver

I'm having trouble interpreting the thermal characteristics of the Microchip CL2N3-G Constant Current LED Driver chip. Here's the datasheet: CL2N3-G Constant Current LED Driver 1 What I want to do is ...
0
votes
0answers
15 views

Is there any CC Led Driver IC that has common GND between led cathode and VIN-?

I have a project that has as 3W (using 500mA) Led and an I2C sensor at the end of a cable, and I need 6 wires for it. (4 to the I2C sensor) and 2 for the led. I’m using the PT4115 CC led driver CI, ...
0
votes
0answers
38 views

Can you use LM5117 as a CC/CV LiPo charger for a 1mAh LiPo cell?

I am trying to build a LiPo charger for a custom 1mAh LiPo cell. The cell is rated for charging with 0.5C, so 0.5mA max charging current. I cannot find any off-the-shelf ICs that can charge with such ...
0
votes
2answers
21 views

Test load capacity of cable & clips with only constant current/constant voltage power supply?

I want to test a 20m wire and soldered alligator clips on each end to see if it can carry the needed current I want to use it for (eg 5A.) Can I just hook it up to the terminals on my bench top (lab ...
0
votes
2answers
57 views

Powering a PLC and transmitters during a power failure

I have 25 locations spread out over a large area we recently had another power outage lasting 48-72 hrs.depending on the location. all locations have UPS back ups with generators. Problem: The ups ...
1
vote
2answers
47 views

Can a DC CC power supply be used for current limiting in a circuit with a battery in series

In circuit #1 I showed typical adjustable power supply usage it can limit voltage and current, all good. It got me thinking. Let's say due to some reasons I can't replace battery with a power supply ...
3
votes
2answers
122 views

How to add CC/CV feature with single LM358 for variable linear power supply?

I have a few weeks with a problem in the design of my bench power supply. First of all I have this design from this guy on YouTube https://youtu.be/_CFIovMkRyg that made a variable power supply using ...
0
votes
1answer
74 views

Do constant current LED drivers consume significant current when all outputs are disabled?

I'm trying to understand the datasheets for several shift-register constant-current LED drivers, such as TLC59281, TLC5916, CAT4016, IS31FL3726. All of them have something similar to this in their ...
1
vote
3answers
80 views

Current mirror with mosfets

This is a current mirror circuit with 2 op amp stages. First stage on the left Voltage from a DAC gets fed into U1 which creates a reference current through Rmir (via the N channel MOSFET) by sensing ...
0
votes
1answer
67 views

Working of op-amp based current source

Can anyone please explain me the working of the circuit attached? I believe the op-amp U1 is connected to provide a stable DC voltage at the non inverting terminal of U3. Is my approach correct? The ...
0
votes
0answers
86 views

Help with a constant voltage led driver

Maybe the title could be better chosen. Hello, I have a 33V 0.8A constant voltage led driver (see picture below, the item no. is GL-1201C-8 if that can help) which no longer works. I searched online ...
1
vote
2answers
91 views

Current regulator using NOT gate

I think I have designed a current regulator. This is the circuit diagram: simulate this circuit – Schematic created using CircuitLab The operation is very simple. Let's say the transistor turns ...
0
votes
2answers
82 views

Constant current source with bypass option

I need a current limiter for a project that I am working on. I understand that I can use a device like the LM317 in constant current mode, but how would I add a bypass circuit so that my ...
0
votes
1answer
109 views

What is the purpose of this transistor in this schematic?

First thing first, I am not native speaker and I am new here. This schematic is reverse engineered from searchlight PCB traces (which is broken) by me. D+ and D- terminals connect to the rechargeable ...
0
votes
1answer
92 views

Limiting the current without limiting the voltage

I want to design a current limiter, for both negative and positive voltages, for my thesis project. My design consists of a voltage source (+/-10V)(X5) and a transimpedance amplifier(X1.) Using the ...
0
votes
1answer
71 views

Create specific resistances across a constant current source

I'd like to emulate the controls on a garage door circuit programmatically. As far as I can tell the circuit acts like a constant current source and sends out 10mA to the wall console. I'd like the ...
1
vote
1answer
65 views

Question on LED usage for constant current LED driver

I am a beginning electronics hobbyist interested in robotics, who started about ~1,5 year ago, and with much to learn. I've got a question on using a constant current PMIC on a PCB project that I am ...
1
vote
0answers
66 views

Designing a PID control with plant controlled using relays

I am working on a project to design a Controlled (Constant Current) DC Battery Charger. The charger has a variable transformer (Plant). The output of which is fed to the batteries to charge them via a ...
1
vote
0answers
59 views

(ARC WELDING) Why does voltage DROP with increasing current?

I hope I'm asking in the right place! I worked with automated TIG (GTAW) welding equipment. I'm confused about how the welding power supply controls the current applied through the work piece. If the ...
3
votes
2answers
148 views

Is it better to use discrete components or voltage regulators for a variable power supply? [duplicate]

I'm a recent graduate EE student and this is my attempt to gain experience and strengthen my resume so I'm eager to figure this out. I'm designing a dual channel floating output bench power supply ...
3
votes
2answers
154 views

Calculate voltage drop across Linear MOSFET in saturation region

Considering the below schematic, how is the voltage drop across the MOSFET calculated when it is operated in the saturation region? I am trying to calculate the power dissipated by the MOSFET so that ...
2
votes
2answers
120 views

Chrome plating current control

I am an electronics hobbyist and this is my first attempt at an analog circuit of this type. Mostly I stick to arduino and LED stuff or just wiring up kits, etc. This is my first attempt at designing ...
0
votes
1answer
40 views

Want to understand the led series/parallel and parallel/Series combination circuit

I'm Working on LED load design circuit which is up-to 64V@1.2A. I thought of giving LED's in series and parallel combination with switches to control the voltage but while searching I found one ...
0
votes
0answers
29 views

Effect of op-amp's input offset voltage on stability of constant current load

I'm designing a simple circuit to have a constant current load with good short term stability. The exact current value is not important, as long as it's stable short-term (10 seconds). R1 is the load -...
1
vote
1answer
65 views

Inductor as current source

In this schematic for an induction heater, there are two inductors used for current sources. My question is what happens if I increase/decrease the inductance? For example, what would happen if I ...
2
votes
1answer
48 views

Can I parallel two constant-current power supplies to drive 1 bulb?

I have a piece of historic equipment that HAS to have an incandescent bulb.* The preferred-voltage bulb (64V) is no longer available, so I'm forced to use 32V bulbs. This one wants 8.4 amps at full ...
0
votes
0answers
54 views

Circuit for OpAmp-MOSFET based constant current source for 0.2 - 1.5A

I'm a beginner in electronic circuit design and have designed my first Voltage based constant current source using OpAmp driven MOSFET (based on this). The intended current output needs to be ...
1
vote
3answers
83 views

Can the voltage drop of an LED driven at a constant current be higher than the supply voltage?

So I've been working on a constant current LED driver project, and I've run into a weird situation. I'm driving 3 parallel rows of 8 LEDs in series (Luxeon 2835 color, green) using a Sparkfun picobuck ...
0
votes
0answers
55 views

Fixed current source

Thank you for reading this question and forgive me if I sound naive. I am working with a device that uses 4-20mA as set-point, I need 3 fixed values to work with this device: (4mA, 12mA, 20mA) The ...
1
vote
1answer
64 views

What's the best way to control DC current in a circuit from 1mA-20mA at 15-30V input with a microcontroller?

I’m trying to create a circuit for iontophoresis that I can control the current of with a raspberry pi or eventually a microcontroller. What would be the best way to control the current? ...
0
votes
1answer
56 views

LM317 adjustable constant current source - Why is the voltage between Output and Adj pins is not always 1.25V?

I am trying to create an adjustable constant current circuit using LM317 to drive LEDs of different colors. More specifically, I want the brightness of the LEDs to be the same, therefore, the ...
0
votes
1answer
35 views

Current decreasing while measuring the current through a constant current source resistor

My Circuit : The above is my circuit. The Forward drop of LEDs is typically 2.8V and a maximum of 3.15V. I designed the current through the string to be around 21mA, so the emitter resistor is ...
0
votes
0answers
52 views

Yet another constant current LED driver design, almost

I am about to design a constant current LED driver, with the following requirements: The LED string is fed with 24 V The FPGA interface is 3.3 V The system consist of 8 LEDs in a row, with ...
0
votes
2answers
40 views

Problem with wide voltage range CC sinking

I want to sink ~10 mA of constant current at wide range of voltages even lower voltages like 10 mV, below circuit suggested to me in one of my older questions: simulate this circuit – Schematic ...
0
votes
2answers
37 views

Constant-current driving with LED Driver and Boost DC/DC converter

Novice here, sorry if I'm missing something obvious. I'm trying to drive 4 strips of 6 low-power RGB LEDs each (APF3236LSEEZGKQBKC) on a 3.3V battery. I have a 12-channel LED Driver (TLC6C5912) which ...
0
votes
1answer
40 views

Understanding the application of a switching regulator as a constant current LED driver

There is an application note from ON-semiconductors which provides a few diagrams to use a well known MC34063 switching regulator as LED driver. it's around the idea of setting the 1.25v feedback ...

1
2 3 4 5
9