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2
votes
2answers
83 views

Simple function generator: is current-limiting/short circuit protection/impedance matching necessary?

I have designed a function generator with the intent to provide test signals to a microcontroller or ADC of some other device. However, I may forget that a year down the line and plug it into some ...
0
votes
1answer
41 views

why is my differential amps error related to load impedence?

So ive built up this circuit, as a simple current limiter. After making sure the output is null when the differential is 0, i get different errors depending on the load impedance even when the both ...
0
votes
1answer
29 views

Explanation and solution of an error in Differential Amplifier Current Soruce circuit

So ive built up the following schematic as a simple current limit circuit. When the current limit is not in place, ie the PNP is conducting "fully", I null any offset errors in the Differential Amp ...
0
votes
1answer
34 views

Reduce output current with same voltage of circuit

I have a lm2596 module and given a 12.5v 3A input to it Now i derive 5v 3A max output from it The prob is the circuit when connected as a charger to phone heats up and doesnt charge well or burns out ...
-1
votes
1answer
54 views

How to deal with inrush current tripping circuit breakers?

I have a temperature controller supplied with 230VAC via a 0.5A circuit breaker curve C. The thing is, the MCB trips as soon as power is turned on. I have measured the inrush current profile without ...
0
votes
1answer
21 views

Need to control 100 Watt Pump With 15 Watt Float Switch

I am an inexperienced hobbyist So My Question may be obvious, but thank you for the help. I have a 12 V battery, which is powering two 12 V pumps. It is a 100 W pump which runs at 7 A on average ...
0
votes
2answers
85 views

Limit current with fewer resistors

Arduino digital pin in OUTPUT mode have low impedance, is it safe to limit current through two leds (connected to two output pins) with one resistor, not two (knowing that leds will go dim and current ...
0
votes
0answers
37 views

12/15V 500mA Current Limiter for Supercap Charging

Long time reader finally asking for some help. I have a 10F equivalent capacitive load that needs to be charged to 15V. My issue is that I only have a max draw of 500mA at 30V available (seemingly ...
-1
votes
1answer
32 views

Current Regulator IC/Transistor [duplicate]

Can anyone suggest a Current Regulator that can bring down 2A to 40mA... I'll be needing 40mA to power my arduino... I'm not that keen in electronics so pls use simple terms in explaining things to me ...
0
votes
1answer
82 views

How to determine current limiting resistor values for push pull amplifier driven by op amp?

I'm looking to increase the output current drive of a high voltage op amp using a push pull amplifier. The OPA454 datasheet includes an application circuit to do exactly this, and includes some ...
0
votes
2answers
115 views

Is resistor on LED's necessary after voltage drop?

Let's say we have perfect 5V DC 0.1A power supply. Obviously for one LED we would need a resistor (I'm well aware of Ohm's law), BUT what if we connect bunch of LED's in series. And the current drain ...
0
votes
0answers
26 views

Limit large currents in a small space?

I've built a variable voltage bench-top power supply from an old printer adapter. I cut off the output wires, and soldered in connections to a buck converter module and a potentiometer. The limit of ...
0
votes
1answer
74 views

USB cable current limit: wire or connector?

I am trying to power a device which requires 5V and 2A through a 5.5mm / 2.1 mm barrel jack connector. SInce I need the device to be portable I am using a battery bank like this: ...
2
votes
2answers
78 views

How to make USB smartphone charger? [duplicate]

I want to make a USB cell phone charger. I know USB operates in 5 volts which means i need to drop down voltage if i have battery potential greater than 5 Volts. I have 12 volts sealed lead acid ...
2
votes
1answer
76 views

Very odd open-drain output design

I ran across a open-drain design and am baffled by the resistor between the nFET source and ground. There are only two purposes that I see it could serve. 1) It's series source termination, matching ...
0
votes
1answer
51 views

Leftover current after current limiting resistor

This question is related to my another question here. In crux, I would like to sink current of TLP521 via 74HC595n shift register. The TLP521 is connected with a resistance such that the current is ...
3
votes
2answers
190 views

How to limit current precisely?

I would like a way to limit the current of a circuit to exactly 100mA (+/- 2-5%). This is on a relatively high voltage circuit (100V to ground), and the current is normally pulsed with pretty fast ...
1
vote
1answer
153 views

Choosing wattage for current limiting filament bulb

I am building a fully featured breadboard/prototyping box for audio circuits and would like to include a current limiting light bulb that will be in circuit when I apply power to the box and then I ...
1
vote
3answers
87 views

Current Limiter, can someone troubleshoot this circuit?

so I am trying to limit the current output with x2 3904 transistors and a sensing resistor. This is currently what I have, but am not sure why it doesn't work. That current supply is going to be a ...
0
votes
1answer
51 views

Current limiting AC

I am currently experimenting with electrolytic marking. I use a DC bench supply with a current dial so I can drive the reaction with a constant current to keep the marking steady and as a plus keep it ...
0
votes
1answer
81 views

Exceeding voltage ratings on microcontroller pins using series resistor

I've been designing a circuit which requires a microcontroller to read a voltage above its current VDD or below its current VSS. I've done this once or twice before by putting a large-ish resistor in ...
0
votes
2answers
209 views

Current limiter with low voltage drop out

I am looking for way to limit the output current from a LDO (Vout = 5V) to max. 150mA. I found only this circuit but the problem with this circuit is the voltage drop Vbe of the transistor Q1 and ...
1
vote
1answer
57 views

Is the excess of current the only problem in a motor overvoltage?

I'm designing a Full Bridge for a Brushed DC motor control. My circuit will have a current measurement, so I'll can control the output current, sinked by the motor. Whit this current control, I think ...
0
votes
1answer
40 views

Charging questions, current limitation and voltage

I'm having few issues with chargers, current delivered to a device etc... just need to connect the dots I guess. When I connect a phone to a charger for example IPhone which is rated at (5v,1A max), ...
0
votes
2answers
46 views

Forward current for assorted LEDs

I have an assortment of T1 and T1¾ LEDs from sampler kits and beginner kits. The kits have sketchy documentation, with missing or inaccurate part numbers. I was able to track down datasheets for some ...
2
votes
2answers
109 views

Simple SPST Switch Circuit - Pull-down Resistor VS. Current Limiting Resistor

Super Noob EE question: Here is my quick draw-up of my SPST switch circuit schematic. I know I probably did not do this right, but if it gets the idea across, then thats good enough for me atm. ...
1
vote
2answers
67 views

User power supply current limit to avoid current limiting resistors for LED

everyone! I would like to know if I can avoid to use current limiting resistors by pushing my power supply to its limits (it already sounds not like a good idea... btw...). Say I have a 3.3V power ...
-1
votes
2answers
119 views

Inrush Current Limiter Failure

I work for a company that builds electric motors, within the last few years they've started building control boards from brush-less dc motors. On the incoming power we have an Inrush Current Limiter ...
1
vote
0answers
40 views

How to restrict power output to a USB client?

...or, how not to charge my phone when I'm using it as a GSM modem in USB tether mode? I've asked this on Unix&Linux but it seems there's no simple way to do it in software. The problem: In USB ...
1
vote
2answers
115 views

Current limiter its not working as it should?

I have created a voltage regulation circuit using op amp and feedback resistors, now I am trying to add a current limiter to the circuit. have read how to create this using two transistors and a ...
3
votes
3answers
572 views

How do I build a 10uA current source/limiter?

I need a constant current of 10uA through a variable resistor in the 100k values. I need to inject the current into that resistor and I need the resistor to be connected to Ground such that I can ...
-1
votes
1answer
136 views

Is there a component that limits current and has a low resistance<0.1Ω

I want to limit the current to 6A. The (roughly resistive) load draws maximum current 9A at 12V. The load voltage is adjustable between 1.5V and 12V. I know that limiting current cause not to reach ...
1
vote
2answers
330 views

Limit drawn current but not voltage (LED driver for 100W LED)

So I have serial connected 8 LiPo's with corresponding controllers to monitor the battery pack. Now, they deliver 32 volts which is precisely what I need but they deliver way to much amperage compared ...
0
votes
3answers
125 views

How should I current limit a LED matrix?

I have an LED matrix which has a maximum peak forward current of 90mA and average forward current of 13mA per LED (dot). If I power only one LED at a time, this one LED will have a very large current ...
0
votes
1answer
54 views

How to implement a current controlled voltage source, or a comparator that trips once a certain current is reached?

I have current flowing through a CCVS, once 10A is reached, the CCVS puts out 10V, which takes a comparator's output high. The current that goes through the CCVS continuous to the load. Is there a way ...
1
vote
1answer
57 views

Voltage stepping and current reduction

I'm designing a drone to use a relatively new form of propulsion, electrostatic fluid propulsion, which requires extremely large voltages (in the order of 10-100kV) running through a wire to ionize ...
2
votes
2answers
604 views

What's the difference of placing multiple resistors and one resistor for limiting the current of LEDs?

I'm looking at a diagram and wondering if I could use just one resistor to limit the current of the LEDs instead of multiple resistors so that the cathodes are all connected to the same resistor. ...
0
votes
1answer
150 views

Comparison of the efficiency of DC motor current limiting / control methods?

I'm using the wheels and motors of an RC toy car as a simple robotics platform. The car has 2 motors, one drives the back wheels, the other steers the front wheels. The steering motor is stalled by ...
1
vote
3answers
163 views

Diode Drop vs Open Drain Output Tolerance

I have an LED Driver IC that states a 5.5V tolerant Open Drain Output. It's Absolute Maximum section indicates 6.5V with a note saying "The input negative-voltage and output voltage ratings may be ...
2
votes
4answers
713 views

How do current limiting resistors work between ICs?

In a simple battery+resistor circuit with a fixed voltage, the resistance of a series resistor determines the current flowing through it. But what happens if this resistor is placed between two ICs? ...
0
votes
1answer
133 views

Current limitation of a power supply by using transistors

DALI standard limits the maximum current as 250mA. I have a 12V source that is capable of supplying more current. I implemented from one of Motorola reference design the below schematics that limits ...
1
vote
1answer
644 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
130 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
382 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 ...
1
vote
2answers
123 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
172 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
56 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
116 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
293 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
1k 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 ...