All Questions
Tagged with current-limiting transistors
38
questions
8
votes
3
answers
13k
views
Help needed optimising simple current limiting circuit
I have been experimenting with simulating current limiting circuits. I am trying to limit current to ~500mA given a fixed 4.8V source. I have started using a circuit like the one found on this ...
- 1,341
7
votes
2
answers
6k
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How does this power supply circuit work?
This is the circuit of a power supply with adjustable output voltage and current, and I wish to understand how it works:
What I did understand:
R1 T1 VD5 - they form a voltage divider which provides ...
- 173
6
votes
1
answer
2k
views
Using a depletion mode mosfet as a current limiting device
I have recently discovered the exciting world of depletion mode mosfets. Curiously, even in this document, I found nowhere that a depletion mode mosfet could be used as a current limiting/inrush ...
- 1,908
5
votes
1
answer
14k
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Current limiters using transistors and diodes
I have been experimenting with simulating current limiting circuits. I am trying to limit current to ~500mA given a fixed 4.8V source. I started a question based on a conventional 2-transistor current ...
- 1,341
5
votes
1
answer
7k
views
BJT Current limiter for linear power supply
I am trying to design a current limiter or my LM317 based power supply using this schema.
The power supply must be able to provide a maximum of 1.5A@30V.
I made some calculations and I would like to ...
- 561
4
votes
1
answer
1k
views
Does this circuit regulate current?
I am being told that the circuit below will regulate current, I am wondering how true that is and how exactly does it do it if so. As far as I can tell: two NPN transistor with their bases biased by ...
- 58
4
votes
1
answer
7k
views
Need help calculating resistor values for IR LED Driver
I'm wiring an IR LED driver for an Arduino project I'm prototyping.
The Arduino will be run at 5V, and I'm planning on using it's 5V output to drive the transistor that runs the LED
The circuit I've ...
- 1,418
3
votes
3
answers
2k
views
How to reduce current in this circuit?
I have the following circuit and I want to reduce the current consumption to the lowest possible.
Basically, I have a series voltage regulator whose output is connected to a transistor to switch on ...
- 79
3
votes
1
answer
4k
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Designing a current limiting circuit for my project
I've got a small DC brushless motor for which I would like to set a current limiting circuit as a protection against over-current.
I thought I could pull it off with a simple fuse (or those current ...
- 31
2
votes
2
answers
2k
views
Transistor current limit circuit - power handling?
I am designing a simple current limiter, which charges a large (4.7mF) capacitor with a charge current of (roughly) 500mA from a supply voltage from about 10-20V - see the below circuit.
My dilemma ...
- 1,504
2
votes
2
answers
210
views
Transistor Limit Current
I am using a LM395T transistor for an inductive load (a motor). The voltage limit is well within the 36V threshold. But current isn't limited. The specs of the transistor say that 1.5 A is maximum. ...
- 21
2
votes
2
answers
277
views
LED Matrix to reduce current consumption
I'm trying to control RGB LEDs via USB. All LEDs have the same color, so I'm controlling them with only 3 PWM signals (generated from a PIC).
The problem I'm facing is to reduce the current needed in ...
- 23
2
votes
2
answers
1k
views
Does a BJT optocoupler have an inherently short circuit proof output?
I want to use an NPN optocoupler (ACPL-214) to drive an offboard relay. I know how to size the input resistor to limit the LED current to 20mA. This will cause the output current to be in a certain ...
- 489
1
vote
3
answers
274
views
Is it possible to overcome a transistor's current limit by running it at lower voltage?
Let's say I have a transistor which is rated for maximum 800mA current at 50V. Is it possible to have it running at 1000mA & 5V for example?
Edit : please provide me some details in your answer ...
- 133
1
vote
5
answers
3k
views
Current limit to 500mA (maximum) at 12V
I have a 12V DC output which can output 1A (maximum.)
I want a circuit that limits the current to maximum 500mA, so I don't accidentally draw more than 500mA as that would probably mean I have shorted ...
- 147