Tagged Questions
0
votes
2answers
35 views
NCP59302 resistor question
What resistors do I need to get 5V on this chip? Sorry, I don't understand the reference to the Iadj in the formula. The section on the Iadj in Adjustable Voltage Design seems circular.
...
4
votes
1answer
106 views
How to build a voltage-controlled current sink / voltage-controlled resistor
I am trying to control a current through several current-mirror device (specifically the IREF pin on the TLC5940) using a single potentiometer. I've tried using a ...
3
votes
1answer
76 views
What do I need to know about leakage current?
I recently suggested a plan of removing one end of a resistor from a breadboard to remove it from the circuit in order to measure its resistance, but my mentor suggested that this won't work for high ...
0
votes
1answer
80 views
Current flows from the source towards the sink
I happened upon the following schematic:
simulate this circuit – Schematic created using CircuitLab
It's supposed to reduce the max.voltage between the GPIO input pin and the current ...
2
votes
1answer
64 views
Octopus Component Tester Analysis
I'm a beginner in electronics and my knowledge is pretty basic. I've been trying to understand how the Octopus Component Tester Works. I know that it's outputs should be used to plot a Current x ...
2
votes
1answer
130 views
Calculating current in a simple circuit
I am new to electronics and am trying to figure something out:
I have a source putting out 12.6V and an unknown current.
I know that I can calculate current by finding the voltage drop over a ...
4
votes
4answers
270 views
Is current the same coming out of an IC as it was going in?
This is my first diagram so keep that in mind. I've come up with this circuit because
I've got some 74** series ICs and I want to be able to make them work. This example is
a simple AND gate with ...
3
votes
2answers
305 views
Do I need to use a resistor with a microswitch to limit current for an Arduino Uno?
I'm using an Arduino Uno to control a small robot and I'm starting to add micro-switches as bump-sensors. I know that when I'm creating a circuit with LEDs I need to use resistors to limit the current ...
11
votes
2answers
294 views
If supply amperage is higher than max. amperage, do I need a resistor?
This is a pretty basic question, as I'm still learning the fundamentals of electronics. I understand the analogy where amperage is compared to the quantity of water moving through a hose.
I have a ...
5
votes
5answers
1k views
How to calculate Power Rating for Zero Ohm Resistors?
Base on my earlier question, since there supposed to be zero voltage (V=IR) drop across a 0Ω resistor, how do we select the power rating of such component?
Example, let say I were to connect a zero ...
0
votes
1answer
169 views
Need help designing a current controlled source in PSpice?
The image below shows an electrical network with 8 elements, a current controlled source, a bunch of resistors, one current source and a voltage source.
Although I haven't labeled them, there are 5 ...
7
votes
5answers
2k views
What is the usage of Zero Ohm & MiliOhm Resistor?
I am new to PCB design and I noticed that some schematics use 0Ω or 100mΩ resistors. What is their purpose and why do we need to use them in our PCB design?
Normally if we wish to probe how much ...
3
votes
1answer
119 views
equivalent load resistance
I have the following circuit
I am having some trouble determining the relationships between Iac, Io and Iacpk. I'm not quite seeing how the final equation for Iac was determined, specifically ...
3
votes
1answer
121 views
Identifying an irreducible circuit?
How would you go about identifying an irreducible circuit? By irreducible, I mean combining resistors whether in series or in parallel to reduce the circuit.
2
votes
1answer
264 views
Are capacitors and inductors capable of absorbing positive power?
A resistor is capable of absorbing positive power.
Why wouldn't this be true for capacitors and inductors?
5
votes
2answers
385 views
Limiting the short circuit current of a power supply
I'm using a repurposed ATX power supply for my hobby projects since it's got 3.3/±5/±12 outputs, all of which are really convenient. But one thing I didn't really think about until I slipped my probes ...
1
vote
1answer
2k views
How to calculate current and voltage draw of a single resistor circuit?
If I have a single 270 ohm resistor connected in a circuit to a 3.3V 50mA power supply, how can I measure the voltage and current for the resistor? I'm familiar with Ohm's law V=IR, where V is the ...
1
vote
1answer
74 views
How do different kinds of motors behave electrically under operation?
This is sort of a follow-up to this topic: Overclocking my toothbrush
I have since measured some numbers with my DMM. Remember this is a tiny brushed DC motor in a $5 toothbrush that I am driving ...
1
vote
2answers
185 views
Thevenin Resistance?
I don't understand our professor's explanation for the answer to this problem:
An LED is connected in series to a 150ohms pull up resistor and a MOSFET with drain-source resistance of 3ohms. The Pull ...
1
vote
0answers
155 views
Cigarette lighter case mod [closed]
(Apologies in advance if this question is out of scope of this stackexchange but I wasn't really sure where else to post it. Any help, advice, useful links would be really appreciated though)
I have ...
6
votes
5answers
1k views
How can I measure the conductivity of a copper rod?
I would like to perform an experiment to measure the conductivity of a copper rod. What device can I use to perform that experiment? Is there such a thing as a conductivity meter? All I found was an ...
4
votes
2answers
1k views
Why does a pull-up resistor not stop current flowing to the input pin when the switch is open?
Sorry this is such a silly question, but I can't seem to understand this. In the third diagram here it shows a pull-up resistor.
I understand that when the switch S1 is closed, current is pulled ...
-2
votes
3answers
573 views
Simple voltage/current question about modifying a voltage-regulated adapter
I have a 7.5V, 2A, Radio Shack AC adapter and I need it to be a 7.5V, 1.5A power supply. It has one of those tip-ring style plugs on the DC end that plugs into a device to provide power.
I need the ...
4
votes
2answers
454 views
Single resistor powering multiple LEDs in parallel where current through resistor is lower than max allowed current for an individual LED
While writing an answer about using multiple diodes connected to a single resistor, I stumbled upon a case about which I haven't read a lot: What happens when we set the resistor so that it sets the ...
8
votes
1answer
394 views
How current limiting resistor for LED affects current and voltage drops?
I'm having a bit of trouble understanding currrent limiting resistors in simple LED circuits. I know that I can determine the optimal resistor like so:
\$\displaystyle R=\frac{V_{s}-V_{f}}{I_{f}}\$
...
1
vote
3answers
254 views
Would any current flow when batteries and resistors are set up like this?
What would the current flow be through the 1 ohm resistor? They are constant voltage sources, not batteries.
1
vote
2answers
296 views
LED “Underdrive”
Is there any possible way I could've messed up this LED? I just found a bi-colored flashing LED this morning and I hooked up different voltages on it in the following order:
3.7V
3.8V
4.5V
...
22
votes
3answers
2k views
Whats inside a resistor?
How does a resistor "resist" current/potential?
I know it's an elementary question, but I'm sure others are wondering too.
2
votes
4answers
453 views
Limiting current from a 5v power supply [duplicate]
Possible Duplicate:
Choosing power supply, how to get the voltage and current ratings?
I have a 5V / 1A regulated supply. I'm thinking of using it to power a PCB which asks for 5V and ...
22
votes
7answers
5k views
Why does a resistor need to be on the anode of an LED?
Please be kind, I am an electronics nub. This is in reference to getting an LED to emit photons.
From what I read (Getting Started in Electronics - Forrest Mims III and Make: Electronics) electrons ...
1
vote
4answers
345 views
Current Indicator
I want to turn an LED indicator on when current is flowing through a path. If there's no current the LED will be off, and when there's current, the LED would turn on.
I've been experimenting with ...
2
votes
4answers
572 views
How many resistors do I need for an 8 switch DIP switch block?
I was thinking of giving each switch it's own pull-up resistor, but this seems like it would be expensive and a little bit of overkill. But using just one pull-up for the entire block seems like it ...
1
vote
3answers
482 views
Calculate Current out of Function Generator
I couldn't find an equation for this on Google/Wikipedia, but does the frequency of a function generator (we'll say that it's a sine wave) impact the current output. Example, if I had a 5 volt source ...
