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1
vote
1answer
96 views

What happens if I supply 18V to a 12V lighted switch?

I am fairly inexperienced with electrical engineering and usually just wing small things I.E. a current project. Basically I have a project box, with a 12v arming switch with a red light in it. ...
0
votes
1answer
47 views

Voltage limiter with LM358

I have a problem with circuit, because I don't know how to design a voltage limiter. I connect to the input (In) sensor that generates signals with range of 240mV to 940mV. Next, The signal output ...
1
vote
1answer
53 views

USB current limiter and under/overvoltage protection

I know recent motherboards already provide these, but lately USB ports are also available in many different gizmos (smartphone chargers, TVs, standalone players, etc.), which I am often tempted to use ...
0
votes
2answers
56 views

Protecting a circuit from the effects of a capacitor's charging

During its first outing, I managed to burn out the (control circuitry) of two of the batteries connected to my LED jacket (see this, this and this question for context.) I thought I should have been ...
0
votes
2answers
60 views

Limiting mains current

What would be the best way to limit mains (240V @ 50Hz) current? I want at least 1A of current. The output should be AC 240V at any frequency greater than or equal to 50Hz. It should be able to endure ...
0
votes
1answer
35 views

Safely Driving a Brushless Motor

I am currently building a quad-copter out of an Arduino. I decided to make my own ESCs using MOSFETs, EMF sensors, and the Arduino. These are the motors that will be driven: ...
3
votes
1answer
46 views

LT1084 as Current control Regulator

I am using LT1084 as a current control Regulator. Circuit shown below Since the transistor Q2 is controlled by a PWM pulse so output voltage of LT1084 is varying as shown below Since it is used as ...
0
votes
2answers
162 views

Batteries & Output Current Limiting

I am currently working on a project that uses a 9.8V 1000mAh battery to power a solenoid, and as I understand it (please correct me if I got this wrong.) a battery capable of delivering 1000mAh is ...
0
votes
2answers
95 views

Maximum op-amp output current

Im looking to drive an LED, but am not sure if i should use an op-amp or bjt configured as a switch. Is it possible for an op-amp to source roughly 10mA; the current needed to drive an LED in series ...
2
votes
1answer
199 views

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 ...
2
votes
2answers
222 views

LM3485 current limiter (\$R_{adj}\$) value selection

I have what I believe is a working buck converter design centered around the LM3485. It's intended to be a Raspberry Pi power supply. The schematic is at Pi Power schematic, which I copy below. ...
0
votes
4answers
175 views

Is it reasonable to use a current limiting diode in place of a fuse?

I'm trying to source some fast-blow 5mA or 10mA fuses but Littelfuse has discontinued the only reasonably affordable ones I have found. My circuit when operating properly will not output more than ...
0
votes
0answers
41 views

DIY Power bank for router? [duplicate]

I'm an electronics enthusiast living in a country with a lot of power cuts, especially through the summer. I want to build a 9V <1A DC power bank for my internet router running on a AC->DC power ...
1
vote
1answer
191 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
vote
2answers
189 views

Peak current limiting motor

I've got a motor driver which can take 3A. But my motor seems to draw more than 3A as peak current when it's been turned on. And I would like to get rid of that since it blew up my motor driver a few ...
0
votes
1answer
105 views

Limiting the current on a PC power supply

I want to use a PC power supply on three 12V stepper motors. The problem is that I want to limit the current of the 12V DC output to 3A maximum for each of the three motors. The power supply has 34A ...
4
votes
1answer
518 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 ...
2
votes
1answer
82 views

Safe way to wire CMOS ICs together

I have a question about the safety (to the ICs) of wiring the output of one IC directly to the input of another IC. simulate this circuit – Schematic created using CircuitLab For ...
2
votes
1answer
96 views

How do variable current limiters work in power supplies?

Bench top power supplies often enable you not only the set the voltage, but the maximum current. How do these bench supplies provide this variable current?
0
votes
2answers
228 views

LM350 current limiter

Why is the following circuit an adjustable current limiter? It looks like a adjustable current source to me. EDIT: I know the difference between current limiters and current sources. Lets analyze ...
1
vote
1answer
189 views

Buck boost converter for lipo 6s charge info request

I need to dimension a Buck boost converter to charge two LiPo battery packs 6s 20ah starting from a variable input voltage. Both packs have their own PCB BMS board. This one: ...
1
vote
3answers
182 views

Determining maximum current through 18 gauge wire in robot arm

For a robotics application, I'd like to power some external electronics and sensors off the logic circuit in a robot arm. The components are a computer (19V, 65W => 5A), 2 cameras (1.2A), 1 light ...
2
votes
2answers
167 views

What is the correct way to handle inrush currents from a DC/DC converter with short-circuit protection?

I have been using CUI VESD2-S24-D12 to generate 24V to run a circuit board. That regulator has been EOL'd with the recommended replacement being PEM2-S24-D12. The two are effectively identical except ...
2
votes
1answer
337 views

DC motor starting and stopping

I'm powering a motor, and instead of rotating at a constant rate, it rotates roughly a third revolution every half second or so; the rotation keeps starting and stopping. There's no load on the motor, ...
3
votes
1answer
176 views

When a pin needs to stay LOW or HIGH, is it okay to connect directly to VCC or GND?

For example, I'm using an Exar Exar SP3220EBCY-L RS-232 transceiver and the typical application loop back test shows that the EN pin is connected to GND and the SHDN pin is connected to VCC. Should I ...
0
votes
1answer
84 views

protecting a sensor component from high spikes when switching power on

I have an electrical scooter which has a "Hall Effect Sensor" in the handle-bar, measuring the magnetic flux to determine the amount of "gas" or gauge. This sensor tends to burn out quite frequently. ...
0
votes
0answers
62 views

Regulation of DC/DC output voltage and current

I found interesting topic recently, here is it: What is causing the oscillation in the feedback loop of an SMPS? Could somebody explain to me, how does this circuit supposed to charge deeply ...
1
vote
0answers
100 views

Voltage-following, short-circuit protected PSU circuit

For a PSU regulator circuit with these requirements: 0-14v adjustable output, set by 0-14v signal, accurate to +/- ~200mV 20A current limiting +/- ~2A which reduces output V as necessary down to 0V ...
0
votes
0answers
79 views

Need to build a current/voltage limiter for Arm cluster

It's been a while since I dove into electrical components (since college) so bear with me here. I am building an ARM cluster here at my house using ODroid-U2 boards and I want to use a battery bank ...
3
votes
1answer
98 views

How to limit current of an AC signal

For my project, I'm trying to work with the principle of electrovibration. This principle is about simulating textures using low current electricity on an insulated conductive surface (see Wikipedia). ...
4
votes
1answer
302 views

Current measurement in a Buck Converter

We have developed a prototype of a PID-regulated Buck converter made around the AVR XMega. 6-17V at the input, 5-10 on the output, 15A current limit, 500kHz PWM switching. The issue is, how to make ...
1
vote
4answers
107 views

How is current controlled in high power applications?

When working with electronics, it is quite easy to regulate current with a resistor, potentiometer, switcher, etc. But take a simple high power application such as an electric stove. What method is ...
0
votes
2answers
250 views

Are there any single chip solutions for single cell LiPo battery protection? If not, any references?

I can't seem to find one, but does anyone know of a single chip solution for LiPo battery protection on a single cell/3.7V battery? Looking for things like over-current/overvoltage/undervoltage ...
4
votes
3answers
367 views

Improving a simple bipolar current limiter

Is there a way to remove the Vbe dependence on bipolar current limiters, or at least, lessen the effects of process variation & mismatch in the topology below? Vin is nominal 22V, but could ...
1
vote
2answers
151 views

Smoothing current drawn by PWM load

I have a PWM load which draws its current from a regulated DC supply. The supply and load will be separated by some distance, and I'm worried that the rapid changes in current through the current ...
1
vote
2answers
832 views

How to limit base current in transistor when collector current is unknown?

In the followig circuit I am trying to replace a push button with a transistor: simulate this circuit – Schematic created using CircuitLab In the schematic SW1 is the push button that ...
1
vote
1answer
408 views

Current limiting on a stepper controlled by L293D on an arduino board

I currently have a bipolar stepper motor connected to a l298n, with one resistor to each coil. The problem is it draws a lot of power when there is no need to, and limits the maximal power of the ...
3
votes
2answers
204 views

Small battery cut off when fully charged

I am working on a small 1.2 V battery. I want the charging current of 7 mA to stop when the battery voltage reaches 1.5 V. What cut off circuit should I use ?
0
votes
0answers
69 views

Do film capacitors need to be isolated and current limited during the burn-in process to prevent them from discharging into one another?

Do film capacitors such as polypropylene and polyester film capacitors need to be current limited with resistors to each unit and isolated during the burn in process to prevent discharges into other ...
1
vote
1answer
89 views

Is there such a thing as a resistive bus bar to substitute many resistors?

I find myself in the position to design Burn-In racks for a capacitor manufacturing company. I am trying to replace the multitude of resistors on boards that limit the current and isolate each ...
1
vote
2answers
444 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 ...
4
votes
4answers
244 views

Can electronics be damaged by under-currenting it?

Someone just asked Can electronics be damaged by undervolting it?, so now I am going to ask under-current. Let's say something requires 10A, 12V, if I limit the current to 5A, could anything go wrong? ...
14
votes
4answers
2k views

Does an over voltage, over current and reverse polarity protection IC exist?

I'm designing a circuit that has the following protection requirements: Reverse polarity Over voltage (60v max) Over current (approx 1A) There's quite a large input voltage range, 10v to 60v. 48v ...
3
votes
1answer
142 views

Is there a way to plot the current to charge a capacitor given that there is a max current in the circuit given by the power supply?

I'm trying to determine the maximum current of a circuit while charging a capacitor but since the power supply has a maximum current of 20mA that is going to extend my charge time longer than the RC ...
0
votes
2answers
441 views

General Questions about PIC24 MCU Input and Output Pin Impedance, Voltage, and Current

I'm having a mental lapse. Try and help me make sense of a few basic things concerning microcontroller pins at the hardware level, please! Correct me if I'm wrong… in the circuit of Figure 1 (see ...
49
votes
1answer
7k views

How can I efficiently drive an LED?

I understand that I can not connect an LED directly to a battery because it will draw too much current. Thus, there must be something else in the circuit to limit the current. What options are there? ...
7
votes
6answers
1k views

Prevent overcurrent while filter capacitor is charged

I have this circuit: On start-up, the power supply experiences an overcurrent condition, because when the capacitor is charged, it looks like a short circuit as seen from the power supply. How can ...
3
votes
1answer
435 views

Driving servos using microcontroller and current limiting

I am new to electronics and would like to design a PCB that uses an Atmel microcontroller, and powers three servos. I was thinking of designing the PCB with a single power supply. The servos I have ...
3
votes
3answers
1k views

Do I need a current limiting resistor when powering an LED below its forward voltage?

I've reviewed the questions: Why can you use an LED below voltage? Is a current-limiting resistor required for LEDs if the forward voltage and supply voltage are equal? But combining them begs ...
1
vote
2answers
389 views

Motor Current Limiting Algorithm

I am building a H-Bridge controller dor DC motors, and I want to add some current limiting on it. Does anyone knows a good algorithm for doing so? I am planning to read the current, and if it goes ...