Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [constant-current]

Questions regarding constant-current supplies, devices and applications, as opposed to constant-voltage supplies. The voltage can vary while the current remains the same. Common in LED lighting applications and battery charging.

Questions regarding constant-current supplies, devices and applications. As opposed to constant-voltage supplies, constant-current circuits adjust the voltage such that the current matches the setpoint value.

Constant-current circuits are common in a plethora of applications such as:

  • LED driving
  • some regimes of battery charging
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Buffering a constant current source IC to increase maximum voltage rating

The actual question: Which of these configurations, if any, is the most effective for my goal of increasing the maximum voltage rating of the outputs of a constant-current driver IC? As established in a previous question, a constant current source…
psmay
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Constant current circuit

How does the red (rot) LED at the input to the base provide a constant current to the other two LED's after the collector, via the transistor? (I have been told that the NPN transistor here has a default voltage of 0.6v, and the red LED at the base…
HokuBoi
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Shunt current source to keep total current consumption fixed in spite of load variations

I have a circuit that is powered from a variable input voltage (20-35V). The load current is variable, but in spite of those changes, I want to keep the total current consumption fixed at some maximum value higher than the largest load…
Luis Carlos
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Constant current source drop

I need some help understanding a little (I guess) thing here. I was trying to understand a constant current source but something happened that I can't understand. When I did a simulation in LTspice and I applied 16V or more, like 30V or even more,…
Jeep nN
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What is a Low Drop Constant Current Driver (LDCCD)?

In this post, the gentleman describes this device but does not give any details about how it works. What's underneath the shrink tube? The easiest way to explain my Low Drop Constant Current Driver (LDCCD) is as follows. It converts the voltage…
Mark Harrison
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LM1085 constant current mode: changing input voltage deviates the ADJ pin in a non-linear fashion

I used the below schematic to output a constant current (~0.92 A) on the RLoad. I turn on/off the N-channel mosfet: simulate this circuit – Schematic created using CircuitLab While current flows through the RLoad, if I tweak the power supply…
Christianidis Vasilis
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How do I get a constant current of 2mA; output voltage of 9V dc?

I need a device that can run on batteries (probably one or two 9V batteries) that will provide an output voltage of about 9V but, more importantly, is constant current of 2mA. This will be dc output. Yes, that's a low current. The output will go to…
martin johanssen
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Is there a CC source that is able to invert the voltage? Which one?

Lets say I have a CC source and set it to 10 mA and connect it to a coil. If I induce a reverse voltage in the coil with a magnet, the CC source should regulate the current to 10 mA by increasing the voltage. Lets say the magnet induces a voltage…
x3oo
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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 working on, and was hoping that I could learn a…
Stathis
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(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 entire circuit was a simple static load, with a…
Chris Jarnutowski
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Is LED properly implemented in the constant current circuit?

Consider this simple constant current source. The voltage is 27 V, yet the indicator LED is rated to a much lower reverse breakdown. Is the LED safe? Will the LED draw current away from the output load? Output would be less than 1.5 mA. Simulations…
user33915
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Special LM317 Constant Current Power Supply

An unusual problem came up that requires a substantial dip in current when the load is increased. The solenoids hold the bass audio contacts closed on a Hammond H-100 Series. The feature is called "String Bass". Here's how it supposed to work: …
ITPhoenix
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help with auto shutoff circuit with negative voltages

I have a circuit that has constant current but the load drops in resistance over time. I need to be able to shut off the circuit once a voltage level drop is reached. The voltage starts at -95vdc and reaches -10vdc when I would like the circuit to…
pascal88
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Using E3640A as current source

There is a E3640A power supply need it to function as a current source. In regular power supplies we set the maximum limit current and the regular voltage we want to output. In the manual shown in the link there is just setting the maximal limit…
Josh23
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Constant current source and halogen light bulb

What happens to a halogen light bulb specified at 10V DC and 1A (10W) when you connect it to a constant current source that runs on 24V DC and can be regulated up to 0,8A. You would need to set the current to a maximum of 10W/24V=0.416A to not…
Newbie2089
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