Questions tagged [parallel]

More than one of a thing, performing the same task simultaneously

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129
votes
6answers
88k views

Why exactly can't a single resistor be used for many parallel LEDs?

Why can't you use a single resistor for a number of LEDs in parallel instead of one each?
40
votes
11answers
147k views

What would happen if I connect two different DC voltage sources in parallel?

I have a computer power supply that I'm hacking together as a bench supply. For this particular model to power on, I need a minimum load across both +5V and +12V. "Easy," I thought, "I'll just ...
39
votes
11answers
35k views

Is paralleling diodes a bad idea?

I'm trying to repair an 800W power supply (see my previous question on this.) One thing that gets me is that the design has two schottky diode packages (in TO-220) in parallel. I was always told this ...
21
votes
8answers
4k views

Two resistors in series

I know the summation equation for two or more resistors in parallel or series, and I know two parallel resistors will give more power. But sometimes I saw some circuits that used two resistors in ...
20
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5answers
23k views

Parallel MOSFETs

When I went to school we had some basic circuit design and stuff like that. I learned that this was a bad idea: simulate this circuit – Schematic created using CircuitLab Since the current ...
17
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4answers
5k views

Will a 0402 0.01 µF ceramic capacitor next to a 0402 0.1 µF ceramic capacitor have any power decoupling benefits?

I always understood that the point of using smaller capacitors in parallel was to provide low impedance at higher frequencies than the bigger capacitors, because the higher capacitance capacitors '...
16
votes
3answers
47k views

Transistors in parallel

I want to use several transistors in parallel to control current through a load. This is to distribute the current through the load across the transistors so that individual transistors with a rated ...
16
votes
3answers
6k views

How many MOSFETs can we safely parallel in condition of very high currents? I had problems with a motor application at 48V 1600A

I tried with some configurations in which 16+16 MOSfets of 240A each (really they are case limited to 80-90A because of source terminal, but i doubled this termminal with a very thick copper wire for ...
15
votes
4answers
2k views

How do I calculate the current in parallel branches?

I've been playing around with an Arduino for a while now, and while I know just enough about simple circuits to get little projects up and running, I still don't know enough to figure out what's going ...
14
votes
7answers
6k views

What's wrong with parallel conductors?

Regarding AC systems (like for homes and such), a circular path is called a parallel conductor. It's illegal (according to the NEC section 310) except under certain circumstances. But I have noticed ...
14
votes
4answers
5k views

Why is the serial connection faster than the parallel connection? [duplicate]

As a software developer the concept of parallel processing usually meant faster processing because it meant things don't have to wait for the other processes to finish if they don't need to. So how ...
14
votes
8answers
1k views

Why does current not increase when batteries are connected in parallel?

I built a simple circuit consisting of two battery holders each including x2 1.5 V batteries, a slide switch, a LED and a 100 ohm resistor. The current I measured with a multimeter when the two ...
12
votes
7answers
13k views

6 LEDs in parallel with a single resistor to simplify soldering

I'm trying to wire up 6 RGB LEDs in parallel, all controlled from a single source (well, three sources, one for each colour). The LEDs came supplied with resistors to limit the current of 270 Ohm for ...
12
votes
4answers
2k views

Why do we use two parallel capacitors in a voltage regulator circuit? [duplicate]

C1 and C2 are parallel capacitors and their total capacitance is 1000.1 uF. I think C1 is ...
12
votes
4answers
33k views

Can I use multiple 18650 batteries in parallel with a standard MicroUSB 3.7V charger board?

There is this Bluetooth Audio Reciever/Amplifier board that I'm looking to get from ebay, and according to the diagram, there's a MicroUSB 3.7V lithium battery charger component in it. With my ...
11
votes
3answers
2k views

Parallel Capacitor Conundrum [duplicate]

I have recently taken on a project that involves improving a circuit and there is a couple of instances where there are two capacitors in parallel with each other. The values of these capacitors ...
11
votes
3answers
2k views

Practical considerations when using a large number of capacitors in parallel

Capacitors can be wired in parallel for higher total capacitance and lower total ESR. What are some practical constraints/pointers for using many parallel capacitors (for example, 10, 25, 50, or 100)?...
11
votes
3answers
993 views

Can I solder a wire between two leads on a PCB to make up for a trace that isn't wide enough?

I have a PCB that has 2 traces on one corner who's width only supports a ~10a load. I need support for a 20a load. Actually, it really only needs to support a 15amp load but I'm trying to build in ...
11
votes
4answers
18k views

Is it good practice to parallel relay contacts for increased current capacity?

Say I have a DPDT relay, like T92S7D12-24. The contacts of this relay are rated for 30A, but there are two sets of contacts. Can I parallel the contacts to get an effective 60A relay? Further, could I ...
10
votes
5answers
4k views

How should I connect batteries in parallel?

I have a pair of these Li-ion batteries. I'd like to couple them so that I get double the current. However, I realize that this could be a Bad Idea™, as the charge could flow in a loop through both ...
10
votes
1answer
773 views

Issue with parallel resistors in LTSpice

I'm trying to build a reactive load box, so I can run a guitar amplifier without a speaker. It's basically a device that simulates the impedance/frequency curve of a relatively high power speaker. I ...
9
votes
2answers
6k views

How to deal with multiple pull-up resistors on modules

I was thinking about doing a modules for a development board I did a few days ago that will include spi/i2c interfaces. The problem is that I didn't included pull-up resistors in the MCU pins in the ...
9
votes
5answers
8k views

DC-DC Boost converter in Parallel

I'm trying to power a 12V 1A device with 1 cell lipo battery. At 12W, the lipo would need to provide 3.24A (assuming no power loss) to step up the voltage to 12V and providing 1A. However the DC-DC ...
8
votes
4answers
5k views

Can you split power between two voltage regulators?

In order to supply more power to a circuit. can you split the power between 2 voltage regulators, in parallel? Can this overpower one of the Voltage Regulators?
8
votes
3answers
2k views

crystal oscillators connected in parallel

why there are two crystal oscillators connected in parallel in the circuit above? i am familiar with the configuration of Q2( look at the schematic) but what is the purpose of Q3? do i really need to ...
8
votes
4answers
24k views

What do the capacitors on IN and OUT of an LM7805 voltage regulator?

Please understand that i am actually a really beginner in electronics. I found a really nice topic on how to create a 5V DC from a 9v power supply. All is ok. But in order to smooth out ripple, the ...
8
votes
5answers
2k views

Is a two-element circuit series or parallel?

Is the voltage source in series with the resistor or is the voltage source in parallel with the resistor? If the voltage source is in parallel with the resistor, then why do they share the same ...
7
votes
7answers
18k views

Programming a parallel port as digital I/O

I'm trying to use a parallel port from a computer as a form of cheap digital output to do various things (control motors, light LEDs, read limit switches, ect). I want to know how to control the 8 ...
7
votes
3answers
8k views

How many LiFePO4 cells can be in parallel?

How many lithium iron phosphate (LiFePO4) can safely be connected in parallel, in order to achieve higher power output (and capacity)? Wired directly together, without components such as resistors or ...
7
votes
4answers
5k views

Meandering traces necessary for 24-Bit parallel RGB LCD interface?

I am working on a project that interfaces an Atmel SAMA5D3 MCU with a LCD TFT display. The interface between both is 24-Bit parallel RGB with HSYNC and VSYNC signals. The resolution of the display is ...
7
votes
3answers
20k views

What are the consequences of connecting two motors in parallel?

I am using two DC motors rated at 36V and maximum current draw of 5A. To reduce the number of motor-controllers, I am planning to connect them in parallel. The two motors are required to run at the ...
7
votes
1answer
587 views

How can SCRs be effectively paralleled?

I'm designing a precharge circuit which will carry 200A when closed. I'd like to use MCO150 Silicon Controlled Rectifiers, but they won't handle the current. Two in parallel looks like the most cost-...
6
votes
4answers
3k views

How do solar inverter systems easily add AC power sources together? [closed]

I understand DC power more than AC power. I know that given multiple DC power generators, easiest way to sum them is by connecting them in series. In paralel you'd need every generator circuit to ...
6
votes
2answers
2k views

Two parallel wires with no resistance - why it's wrong?

I've built the scheme below in circuit simulator and it didn't work because of "wire loop" mistake. Why it's wrong? Why it's wrong physically? The simulator is falstad.com/circuit
6
votes
3answers
3k views

ASIC vs ? — Performance & Cost

I'm interested in creating a custom linux based solution that will crunch sha256 cryptographic algorithms at insane levels of speed. I'm also on a limited budget... I have no background in EE but I ...
6
votes
3answers
3k views

dual potentiometer wired in parallel

I'm trying to understand if those two circuits are 100% equivalent. I mean, if I use a dual gang 100K linear potentiometer, and wire it like VR1A-VR1B, do I get a single potentiometer exactly like ...
6
votes
2answers
3k views

Can I parallel multiple resettable fuses to achieve a higher current rating?

I have an application wherein I spec'd a fuse, rated for 80VDC 500A. The customer is concerned about what happens if they have to replace the fuse, it being rather difficult to access. They suggested ...
6
votes
1answer
20k views

Why is there risk of overvoltage when jump-starting a vehicle?

Ford Focus C-Max manual describes jump-starting procedure as follows: shut off everything, connect the jump cables, start the donor vehicle engine and let it run for a while, turn the ignition key on ...
6
votes
2answers
889 views

Recommended Layout for Parallel Current Sensing Resistors

I'm working with 12V DC systems and high currents (up to ~40A). In order to meet the wattage and price requirements for my design, I'm using two parallel sense resistors. The IC I'm using for sensing ...
5
votes
3answers
3k views

Is it true that on a modern processor, parallelism is possible on a single core?

Final Edit: I just realized that when use the word "parallelism", it's almost parallelism==ILP, I originally thought even a single instruction could be divided into ...
5
votes
3answers
1k views

Paralleling mosfets to reduce Rds On?

This if a fairly simple question. I have some APT43M60L MOSFETs with a fairly high on resistance. They get quite hot and waste a lot of power in my induction heater. They work great but get really hot ...
5
votes
5answers
371 views

Managing circuits beyond a basic level

I am very new to electronics so please go easy on me. Whilst I have read a couple of electronics fundementals books so far, one of the things that confuses me the most about electronics is how ...
5
votes
2answers
3k views

Using Pullup and Pulldown Resistors

I've been researching pullup and pulldown resistors after seeing them used in many digital circuits and while I understand what their purpose is, I haven't found any resource on how to determine the ...
5
votes
3answers
2k views

For the resistor circuit shown in the picture, what must be the missing resistance to give a total resistance of 252 ohms?

After my calculations, I keep getting 1100 ohms, but the back of the book is saying 85 ohms. 85 seems to fit in better with the other numbers, but I can only get 1100 to add up. Here's my ...
5
votes
4answers
553 views

Parallel Power Supplies with Ideal Diodes

I'm working on a project that operates at 5v - and can draw UP to 10 amps. Under normal conditions, it won't be doing that - probably closer to 3 amps, and (if configured for low-power) only 450mA or ...
5
votes
2answers
402 views

Mathematical approch to measuring current, voltage and resistance of mixed series and parallel

If there is a circuit like the one below, where all resistors are 1k ohm, how does one determine the currents? The voltage sources are all 10 volts. The problem I am having is that I do not know if ...
5
votes
3answers
15k views

Why is connecting two different voltage sources in parallel dangerous? [duplicate]

I'm working through a circuit analysis text on my own for the purposes of getting started with Arduino. I just came across a box that explained why putting two different voltage sources in parallel is ...
5
votes
4answers
3k views

Why use FREERTOS instead of the interrupt mechanism on a microcontroller? [duplicate]

This might be a very stupid question. I have experience with embedded software on bare-metal and just started with FREERTOS. However I don't really understand why one would use FREERTOS instead of ...
5
votes
1answer
850 views

Replacing two LEDs with a 2-pin, bicolor LED, using a circuit that reverses polarity based on two inputs

I'm working with a commercially available circuit that can optionally be configured to disable its internal LEDs and use two external LEDs. This post discusses the use of external LEDs. One LED or the ...
5
votes
3answers
750 views

Multiple switches, same function. Can they be wired in parallel to a single I/O pin?

I'm working on a Raspberry Pi project that requires 30 separate momentary switches to be hooked up to trigger the same function within the software. It's for an art project. I don't need to ...

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