49
votes
Accepted
Two resistors in series
It's the voltage rating on the resistors that is important here. They are powered from rectified 230 V AC and they need to have the correct voltage rating to suit their application. Two resistors in ...
- 473k
40
votes
Accepted
Two LEDs connected in series don't work
The LEDs both need about 3V to work, so together in series they need about 6V to work, but the IO pin only gives out 3.3V. So there is no way the LEDs could work in series.
Also do not connect LEDs to ...
- 172k
36
votes
How do solar inverter systems easily add AC power sources together?
Because UL 1741 does all the heavy lifting for you.
That's what makes it "so easy". UL 1741 is a complicated spec for "grid-tie solar inverters".
Aside from doing their usual inverter thing (...
25
votes
Accepted
Heat lost in ideal capacitor charging
The problem with these theoretical examples lies in the fact the current is assumed infinite for 0 seconds. Crudely substituting this in the conservation law:
$$ \frac {\partial \rho }{\partial t} +\...
- 10.9k
22
votes
Can I stack optocouplers in series to make a higher specification part?
The way you want to do it won’t work. The optocouplers don’t switch equally fast and will fail due to overvoltage.
Use a single optoisolator and a cascode. The cascode in this case is the NPN ...
20
votes
Two LEDs connected in series don't work
LEDs have a forward operating voltage "Vf".This varies with current but is around 3V for both blue and white LEDs at typical operating currents.
If you place 2 LEDs in series they would ...
- 152k
20
votes
Accepted
What is the reason to connect 4 resistors of the same value as 2s2p? (image)
Dissipation (4x) or pulse power capability (4x) since cost can go up much faster than those capabilities— or redundancy (no single failure will cause a short or open).
The latter strategy is used in ...
19
votes
Two resistors in series
Reasons someone might put two resistors in series in a volume design:
A bit higher power was needed than what the commonly stocked parts can handle.
Let's say a company standardizes on using 0805 ...
- 315k
17
votes
Accepted
Is it possible for series connected battery cells to provide different currents?
In a series circuit, the current in each component of the series will be the same. This is true no matter what the component may be: resistor, capacitor, inductor, diode, battery, etc.
- 16.4k
17
votes
Accepted
Is it viable to connect multiple ESC units in series?
As someone who spends all my time at work connecting things in series: Don't!
Moreover, don't connect anything but resistors in series unless you absolutely have to.
What will happen is that one ESC ...
- 16.8k
14
votes
Benefits of multiple op-amp gain stages in series?
In addition to improving the gain-bandwidth product of the circuit, splitting the amplifier into multiple stages allows you to use choose different op amps which are designed to excel at particular ...
Null♦
- 7,652
14
votes
Accepted
Why does current not increase when batteries are connected in parallel?
First off, I want to warn you just a little bit about putting battery systems in parallel. It's usually not a good idea because often the two batteries (or battery systems) don't have exactly the same ...
- 78.7k
14
votes
How do solar inverter systems easily add AC power sources together?
It is really not that easy. It's easy for you because standards and regulations have been put in place that affect the power company and anyone selling you grid-tie inverters. The system is designed ...
- 47.1k
14
votes
What is the reason to connect 4 resistors of the same value as 2s2p? (image)
As the others have said, it's most likely about dissipation and pulse power.
But there is also cost.
If you already have a reel of 10R chip resistors of one value loaded on the pick and place machine, ...
- 81.9k
13
votes
Accepted
Benefits of multiple op-amp gain stages in series?
Noise:
Say your opamp has GBW of 10MHz and noise of 1µV (to keep things simple). The source has 1µV RMS noise also.
Each opamp will amplify its own noise by the circuit noise gain, plus the noise of ...
- 81.9k
13
votes
Heat lost in ideal capacitor charging
When masses collide in an inelastic manner, momentum is conserved but energy has to be lost. It's the same with the two-capacitor paradox; charge is always conserved but, energy is lost in heat and EM ...
- 473k
13
votes
Reversed DIP Switch
This is what your circuit looks like:
simulate this circuit – Schematic created using CircuitLab
When you close the DIPSW the LED will be shorted thus the current will flow through the DIPSW ...
- 38.5k
11
votes
Accepted
Is there any pitfall to using resistors in series AND parallel for an LED array?
Your LEDs may or may not work exactly as you expect, depending on what you expect.
The change in brightness when operating the switch will vary depending on whether you have 1 or 9 LEDs lit. With 1 ...
- 174k
11
votes
Should Resistor be before or after an LED series
As others have mentioned it does not matter where you put the LED in the series chain. You can even put them in the middle if you want.
However, there is another factor not discussed here so far.
If ...
- 47k
11
votes
Accepted
Design of very long serial signal systems
Software
In software (regardless of the hardware chosen), you basically want debounce code which ignores transients.
There are endless algorithms, but perhaps one that is suitable is:
sample at high ...
- 16.2k
10
votes
Accepted
Can I use 1N4148 diodes instead of a 1N4001 diode for reducing the speed of a 5V 1.8W fan?
The 300 mA rating is in the Absolute Maximum Ratings table - you don't normally want to go near those ratings.
The 1N4148 is intended as a small signal diode. If you look at the Electrical ...
- 60.7k
10
votes
Accepted
How do solar inverter systems easily add AC power sources together?
Question isn't clear. What do you mean with "sum"?
Differences are pretty complicate but, I attempt the silly thing to describe it in 2 sentences.
If you place DC sources in series, you get the ...
- 405
10
votes
What is the reason to connect 4 resistors of the same value as 2s2p? (image)
Four smaller and cheaper resistors that can dissipate less can be used instead of single larger and more expensive resistor that can dissipate more.
- 172k
9
votes
Can you connect multiple PCBs in series?
can we assume the voltage drop across each is 12V DC?
No you can't because each PCB may appear as a different load resistor and, the PCB with the highest resistance between its power terminals will ...
- 473k
8
votes
Using Audio Jack Switches as Paralell/Series toggle? (guitar amp and cabinets)
simulate this circuit – Schematic created using CircuitLab
Figure 1. Your three options with your kit.
simulate this circuit
Figure 2. Single or series connection using switched jacks. The ...
- 180k
8
votes
Can I use 1N4148 diodes instead of a 1N4001 diode for reducing the speed of a 5V 1.8W fan?
Components in series have the same current through them — it doesn't divide. All of the current goes through all of the devices.
If one diode has a limit of 300 mA, then two of them in series ...
- 178k
8
votes
Is it possible for series connected battery cells to provide different currents?
I think the key part is the BMS system you mentioned. I believe it refers to charging control circuits that have circuitry to monitor individual cells or sets of cells, and circuitry capable of ...
- 296
8
votes
Accepted
Can you connect multiple PCBs in series?
Assuming that when you say "connect in series" you mean "connect each board's one and only power input in series with the next ones one and only power input", then all of the above,...
- 47.1k
7
votes
Connecting the primaries of two 110V transformers in series across 220V
You cannot guarantee that the primary current taken by one transformer will be close to the other transformer. This inevitably means that when primaries are put in series, one might hog more voltage ...
- 473k
Only top scored, non community-wiki answers of a minimum length are eligible