Tagged Questions
2
votes
4answers
113 views
Voltage Converter's GND Problem
I am confused about the ground part of a voltage converter.
This is a typical voltage converter. As you can see the the main voltage is 230V, and the output is 5V. Look at the output 0V, which is ...
1
vote
1answer
107 views
Keeping the output of a heated LM317 constant
I have built a power supply using an LM317:
simulate this circuit – Schematic created using CircuitLab
When the supply is on for a rather long time (several hours) with a respectable ...
2
votes
0answers
89 views
7805 5v regulator outputting 4v [duplicate]
I'd like to start out that this is my first ever electronics project. I built a 5v power supply from here, using a 7805 5v linear regulator. the only problem is that it is outputting 4v instead of 5v. ...
0
votes
1answer
213 views
How do I test an xbox 360 slim power brick? [closed]
I've looked everywhere and I just want an answer to a simple question. I have an xbox 360 slim and 2 power bricks I am trying to fix. I also have a multimeter. I know the power supply is meant to ...
1
vote
1answer
121 views
Getting a higher voltage from a battery than specified
This may be a totally stupid question, but say I have a battery that supplies power at 7.5 V. Is there any way to boost its voltage to provide 9 V?
I know you can step down voltages in many ways ...
3
votes
3answers
210 views
Calculate power supply on distance
I need to provide 12V DC to a DC brushless motors that need 12V 30A at distance of 30m from the source.
The cables I can us are 20 Gauge, I know that the cables are loosing power, how can I ...
6
votes
7answers
583 views
Simplest Way to step down the 220AC with more than 10% efficiency
Objective
I want to design a tiny single packaged mains-powered temperature sensor. Possibly as a multi-chip module (MCM) on one small PCB board.
Constraints
The temperature sensor I plan to ...
3
votes
1answer
70 views
Can I power an interactive 'live' wall with copper tape and a 15v ac adapter?
I'm working on a class project to make a living wall with LEDs, paint, and copper tape spiral magnet speakers. I have a 15v ac adapter to power the wall and copper tape to connect the LEDs in parallel ...
0
votes
1answer
594 views
Voltage between ground and positive / negative terminals, is this correct?
I recently acquired a used BK Precision 1660 triple output power supply.
Upon powering it up, I did some basic voltage checks. On both the master and slave outputs, voltage between positive and ...
3
votes
3answers
210 views
Voltage regulator 'hiccups' when gate pin of MOSFET is touched
I've been struggling with the following circuit which includes a Raspberry Pi:
That's a 5V voltage regulator (with protective capacitors), and a DC motor over on the right, and an IRF510 N-channel ...
2
votes
2answers
377 views
Will a 5.1V adapter charge a device that currently uses a 5.5V adapter [duplicate]
Possible Duplicate:
Choosing power supply, how to get the voltage and current ratings?
I have a device (a Geneva XS portable Bluetooth speaker) which is supplied with a power adapter that ...
0
votes
1answer
176 views
Atx psu 7v output
What is an easy way to get 7-7.2vdc from an scavenged atx psu? I had thought about using a lm317 but I'm going to need at least 5-7 amps of current, and the 12v-5v split just sounds like a really bad ...
0
votes
0answers
34 views
Can I use a 12V / 2A power supply with a 12V / 1.3A motor? [duplicate]
Possible Duplicate:
Choosing power supply, how to get the voltage and current ratings?
I just ordered this motor, and the description says it was tested with a 12V / 1.3A power supply.
Now ...
3
votes
2answers
175 views
Stepping from 5 V / 1000 mA to 3 V / 750 mA
I'm trying to go from 5 V, 1000 mA, which is a USB transformer for Apple devices, to 3 V, 750 mA (which is a small camera I have). I have purchased a NTE1904 3 terminal volatage regulator which 3.3 V, ...
1
vote
1answer
264 views
LT3080 regulator question
The datasheet of the LT3080 voltage regulator says that "For true zero voltage output operation, this 1mA load current must be returned to a negative supply voltage."
What exactly does this mean? How ...
5
votes
1answer
242 views
'Voltage Fuse' or better
I have a power supply with multiple outputs (5v, 12, 24v)
According to the manufacture (and after testing) there must be a minimum load on the PSU for it to supply the stated voltages. Without a ...
3
votes
1answer
215 views
Battery in parallel with main power source
I have a system that is powered by a main voltage supply and I want to connect it to a battery for backup, in case of power outage.
I need to know what would happen if I connect the system with the ...
6
votes
2answers
424 views
Why does a printer's inrush current double for 240V vs 120V?
In this answer, the inrush current for a laser printer is listed as follows:
...
3
votes
2answers
196 views
Current path question
This may be a stupid question but it seems that I don't have a clear image about how this works exactly.
So my question is:
In the attached schematic, why will there always be a higher current in ...
2
votes
2answers
132 views
Negative Voltage Breakers?
I've been reading a bit on negative voltage, but I have a question that will probably reveal some ignorance, so I apologize ahead of time. If someone tells me that they want a (2) 5A breakers, (1) ...
-1
votes
1answer
100 views
Is my device burnt? [closed]
I live in Israel,
we have here a 220V network.
I bought for my baby this product from eBay:
which has these technical data:
And so, I also bought (from Israel) this adapter:
the device ...
0
votes
1answer
102 views
Using a pc power supply, any risk to electronics? [duplicate]
Possible Duplicate:
Choosing power supply, how to get the voltage and current ratings?
I have a pc power supply which I modded to use as one for my projects. It's really cool, and I love ...
1
vote
3answers
608 views
Using ATX PSU as stand-alone power supply: PSU doesn't stay on longer than ~1 second
as the title suggests I am trying to use an ATX power supply (Seasonic modular X-1050) as a stand-alone power supply. I have roughly followed guides available online, the best of which I have found to ...
5
votes
5answers
438 views
Running my atmega8 at 5.5V, risky?
I have just received my first microcontroller, an Atmega8. I will soon be making a voltage regulation circuit for it to run at 5V, but I don't have all the parts yet.
Instead, I have a 5V DC 1000mA ...
2
votes
2answers
191 views
How to best estimate power consumption for a system?
I'm not an engineer, I'm a software guy getting into hardware - so bear with my ignorance!
I'm in the process of building a system with many components (e.g. a computer, many sensors, a few motors, a ...
39
votes
3answers
18k views
Choosing power supply, how to get the voltage and current ratings?
Power supplies are available in a wide range of voltage and current ratings. If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to ...
4
votes
2answers
223 views
Understanding electric power
While in a mood to purchase a Peltier strip, I visited the amazon page which stated the specs of a Peltier thermoelectric cooler, one stated 12 V and 92 W and other one stated 12 V and some 77 W.
As ...
2
votes
1answer
123 views
Why isn't there an electrical potential?
I have two different DC power supplies (6 and 12 volts, let's call them A and B). They connect to the wall and provide a negative and a positive terminal each.
I tried to measure the voltage between ...
9
votes
2answers
4k views
Why do many laptops run on 19 volts?
Typically mobile devices that have a mains-powered supply will accept voltage that is multiple of some single battery voltage. For example, 4.5 volts is 1.5 volts (AA primary battery) 3 times and 36 ...
1
vote
3answers
421 views
LM317 Ground Problems
I have a LM317 setup as a 3.3V regulator. I am getting 12V input from an Agilent Technologies E3631A Variable DC Power Supply. On this same board I also have a LM7805 regulating to 5V. All of my ...
1
vote
4answers
3k views
How can a Arduino (5v) power a device that operates on >12v?
Say I buy a device that requires 25 volts to function, but I want to control it using my 5v arduino. How would I go about powering/controlling higher voltage devices?
3
votes
3answers
1k views
5V to 160V DC converter
I need a DC-DC convertor to bring a 5V input up to 160V DC output. Does anybody know off any of the shelf parts that would manage this? The high output needs to supply minimal current (uA) we really ...
5
votes
1answer
293 views
DC PSU questions (+/- voltages, home-built ammeter)
This turned out to be several questions, though they're all closely related; I hope that's OK. Due to this, I'll create a small "summary" with just the questions at the end.
I'm looking at designing ...
2
votes
1answer
584 views
Power supply compatibility - 4.5v and 5v
I am wanting to replace the power supply for my Dreamplug (too chunky for a power-board and requires a converter to an AU plug). I have another power supply, however I am unsure it will work (without ...
0
votes
3answers
565 views
Get 17V from PC PSU
How can I get 17V from old PC PSU?
I have +12V and +5V output, can I get them to one +17V output?
5
votes
2answers
524 views
Can 12V Batteries be made to act as a ±12V power source?
I am an undergraduate electrical engineering student, and as a final project for one of my classes I made a speaker system which could play music connected through a 3mm cable. The system was powered ...
0
votes
2answers
843 views
Can I use a voltage divider and/or voltage follower to produce 1V from 9V for an op-amp oscillator?
For a circuit I'm building, I'm using an op-amp oscillator to generate a sine wave. The sine wave will have a maximum voltage of 1V and a minimum voltage of -1V. The circuit will be powered by a 9V ...
1
vote
2answers
114 views
Measuring supply voltage
The documentation for a chip that I'm trying to use says it needs 2.7 to 3.6V. When I use a multimeter and put on probe on Vin and the other on GND I read 1.7V. Is this the correct way to read supply ...
4
votes
4answers
2k views
how to build a low-voltage disconnect switch for DC 12.4V 70A?
How can I make a device that will make the power connected as long as the voltage of the power-supply keeps over 12.4 V (adjustable) and disconnect it if it falls below?
It also must connect the ...
8
votes
2answers
804 views
Is it normal for DC wall adapter power supplies to provide voltages above the nominal ones?
When I measure a 9V DC wall adapter power supply with a multimeter it shows 11.8V. When connected to my board this voltage lowers to 10V. Is this normal? Should I be afraid of toasting my 1117CD-5.0 ...
