Where power is a primary concern for the design under discussion. Use the "low-power" tag when that applies.
3
votes
1answer
99 views
Kilowatt Hour Definition
This is a very simple question but something that I'm not able to wrap my head around. This Energy report states generated electricity. But what does "generated killowatthours" mean? I know that ...
1
vote
1answer
62 views
Upgrade cheap power supply
I want to power my project(AVR uC + RF transceiver) with a fake iPhone charger whose internal is the same as this one, but with a smaller input and output capacitor. I therefore suspect that the ...
2
votes
0answers
125 views
How to make your own EL Wire (electroluminescent wire) inverter
I would like to make an EL wire (electroluminescent wire) inverter because I can't seem to find a commercial inverter that can drive the right length of wire from the batteries I would like to use: ...
1
vote
2answers
117 views
Choice of 5V connector for power
For a small project I'm working on, I am trying to decide the best route to take for the power connection to the device. It will be running on 5V and, in its current iteration, draws less than 100mA ...
0
votes
0answers
47 views
Power management/collision with USB OTG [closed]
I've recently got a device (actually - Samsung Galaxy SII) with USB OTG capability and am curious how does it resolve power conflict.
If the device is plugged to power supply or computer, it charges ...
-4
votes
1answer
60 views
how do i power my LEDs [closed]
I am currently working on a display board for my church. It contains a static LED display built with light chaser technique and a moving dot matrix display. I am through with the last two but to ...
0
votes
3answers
167 views
How to control 0 to 110 of AC with microntroller rms output of 0 to 5 v
Is it possible to control high current with small rms voltage?
UPDATE
Do you think that this is gonna work?
7
votes
2answers
197 views
Grounding and why charge leakage occurs
A basic nugget of info is missing in my end-to-end picture of how grounding works and why it's important. When a voltage is applied in a circuit the electric current starts flowing (or the field ...
5
votes
5answers
158 views
How to determinate a reasonable clock frequency for a MCU?
Currently my datalogger is running at 12Mhz, and sleeps 90% of the time. When it's active its mostly blocked by I/O like SD-card or UART.
I suspect the system would still work at 6 Mhz, but how do ...
2
votes
2answers
100 views
Mains on a single core wire?
I have some single core wires normally used in simple breadboard circuits to handle 5V.
I have built a power supply circuit on a perfboard, with a standard transformer + capacitor + 7805 build. Can ...
1
vote
1answer
81 views
Powering the output side of a voltage regulator?
Would powering the output side of a voltage regulator cause any damage to it? (The ground pin would be attached as well) It will not be normally, but I am making a multi-voltage power converter and ...
0
votes
0answers
86 views
ULN2003a and Relays
Hi! We need help for this problem.
This system is about switching relays. We are using one 6V relay for the six loads for the light breaker 1 and light breaker 2.
The light breaker 1 relay and ...
0
votes
3answers
154 views
Lower Voltage of 15 VDC Power Supply to 13 VDC for DC Blower
I have a centrifugal blower, model 007-A42-32D, that uses 12 VDC at 17.5 amps. The performance information provided by the manufacturer, SPAL Automotive, was acquired at 13 VDC.
I have a power supply ...
1
vote
2answers
94 views
Question about using N-channel MOSFETs in a current sharing controller
My question is specifically regarding LTC4353 :
Product link: http://www.linear.com/product/LTC4353
Datasheet link: http://www.linear.com/docs/41582
Looking at the diagram on the product ...
1
vote
1answer
86 views
What's the input resistance of an opto-isolator?
I need to sense if a 48 volt power supply is supplying voltage or not, I plan on doing this with a opto-isolator and I am happy with the output circuit from isolator.
Can I connect the input of the ...
3
votes
1answer
137 views
Why does this insulator separate two conductors with equal voltages?
Here goes a view-from-below picture of a 3 kilovolts DC railway catenary
Here B is a suspension cable, C is a two-stranded contact wire - one which the train pantograph touches. Between B and C ...
1
vote
1answer
97 views
powering a fan with ATX PSU 5v standby when off, with 12v when on
Using an ATX PSU, how would I design a circuit to power a load (dc fan) with 5v standby when PSU is off, and with 12v when PSU is on. I want to control (on/off or pwm, it should not matter?) the fan ...
3
votes
3answers
121 views
How can I switch a high current with a low-rated switch?
I'm designing and building a breadboard power supply for myself, which draws power from an ATX-like SMPS (Mains in, single Molex plug out) via a 4-pin Molex connector. The design includes a switch to ...
5
votes
1answer
132 views
Any disadvantages to single-supply mode?
I am using the ATMEL ARM SAM4S MCU for a project. It supports a single-supply mode where an internal voltage regulator provides the 1.08-1.32V necessary for VDDCORE and we need only provide 1.62-3.6V ...
4
votes
2answers
158 views
Creating a high-current bus on a PCB
I'm planning a custom power-distribution / fuse-board for in-car application, but that requires carrying high currents (50A+ @12v*) on a PCB trace. Since I'd like to keep the board cost, and physical ...
0
votes
0answers
87 views
Design of an inverter required to run 5 laptops and 1 LCD (32") for 8 hours
I need to design an inverter which will run 5 laptops and one 32" LCD screen for 8 hours.
As per my calculation,
average laptop = 135watts
average LCD = 82watts
wattage for 5 laptops = 135*5 = ...
-6
votes
2answers
150 views
Battery with most mAh that outputs between 1 and 1.5v? [closed]
I am looking for a rechargeable battery between 1 and 1.5 volts that can provide this voltage for the longest amount of time (most mAh). Any suggestions? Thanks.
1
vote
0answers
81 views
What are the different ways of switching 110 VAC power?
I am working on a project where I need to break the path providing 110V to a motor.
What are different ways of doing it? I am aware of only two ways:
Using a mechanical switch,
A relay.
Are there ...
-3
votes
4answers
148 views
12VDC power supply question
I have a 12VDC 500mA power supply and I want to power two (2) separate items, by using a "Y" adaptor. The first item is supposed to use this exact power supply, but the second item tells me to use a ...
1
vote
3answers
173 views
What is typical power consumption of FPGA devices
I am new to this site and had one question. I know typical CPUs have power consumption (TDP) in range of 100-200W, for example Intel Core2. I wanted to know what is typical power consumption of FPGAs. ...
2
votes
2answers
164 views
Cleaning up 4.8V and 10.8V DC power affected by spark ignition system
I am developing an autonomous heli drone, powered by a petrol engine. Servos and radio receiver use power from a nominal 4.8V NiMH battery pack. Autopilot takes power from a nominal 10.8V NiMH ...
6
votes
2answers
270 views
Is there any way to boost DC current?
I'm designing a circuit to charge mobile battery. My source is giving a DC output of 15V, 100mA, whereas I need DC 6V, 450mA for charging. Is there any way to boost DC current?
0
votes
1answer
591 views
How to calculate voltage drop over and power loss in wires
How do I calculate the voltage drop over wires given a supply voltage and a current? How do I anticipate on voltage drop so that the final load has the correct supply voltage?
What will be the power ...
-4
votes
0answers
35 views
Electrical wiring sparked and now I have now power in my bedroom [duplicate]
I tried to replace the ceiling light holder in my bedroom, but I accidentally touched it with my pliers. It made a spark and all of the power in my room is gone?!
What do I do!?
-6
votes
1answer
49 views
Ceiling light holder [closed]
I touched the wires of a ceiling light holder with plyers, it made a spark and all of the power in my room was gone. WHAT DO I DO?
3
votes
3answers
145 views
Do I need to use any external parts with a voltage regulator?
I have recently bought a voltage regulator (link, specs, and datasheet below) and I am regulating a AC-to-DC 9v power supply into 5v with as little components as possible. In the datasheet, all of the ...
3
votes
1answer
152 views
Should I expect my power line to be this noisy?
I'm building a circuit that contains a 555 timer wired to operate in monostable mode.
In the final project, the trigger to the monostable will be driven at around 60Hz, with the output driving some ...
2
votes
2answers
159 views
Converting 12VDC to 1.5VDC
How do I convert 12vdc to 1.5vdc for flashing mini-lights on my HO Scale Railroad system?
The flasher will drive 2 alternately flashing bulbs (1.5 volts each)
The maximum output of flasher is 100mA @ ...
2
votes
2answers
55 views
Can you work out real power by taking the average of several measurements of instantaneous power?
Pretty simple answer to this, but I have managed to get myself into a lot of confusion
Can you work out real power by taking the average of several measurements of instantaneous power?
I was hoping ...
1
vote
0answers
28 views
Laptop AC Adapter using a higher Amp or Watt rated and effects [duplicate]
I have a laptop AC Adapter that has a power specification of 19v 3.42A 65watt and the laptop power requirements are 60 watt. What are the likely effects of using a higher rated AC adapter, ie 19V ...
-4
votes
1answer
70 views
Laser Printer Power Problem [closed]
I'm puzzled. Just got a new laser printer, it's directly connected to the wall. I also have a 700VA UPS with all my computer/networking gear at about 50% load. Here is my problem: if I power on the ...
2
votes
1answer
203 views
Kicad Eeschema 'Power Symbol' with local scope?
AFAIK, Power symbols in Eeschema have global scope. What is the best way to achieve local scope power rails? The only one I can think of is using normal net labels or hierarchical label.
When does ...
3
votes
2answers
157 views
Maximum power for Arduino Monster Moto Shield
I'm reading the specs for the SparkFun Monster Moto shield which specifies that
Max Voltage is 16V
Maximum Current 30A
Given Ohm's law, does that mean that the maximum power is 480 watts? That ...
7
votes
3answers
173 views
Do I need input capacitors for a regulator following a regulator?
My system contains several switching and linear regulators:
Main DCDC regulator taking the incoming 50v power down to 6v.
Several small regulators (DCDC and linear) creating 3.3v, 5v, etc. from the ...
2
votes
1answer
105 views
Restoring old SR-50 Calculator, odd Charger Voltage
I have an old Texas Instruments pocket calculator, for fun decided to get it working again. It is strictly a NiCd powered calculator, no alkaline recommended.
The charger is the 9130, says output 6 ...
2
votes
1answer
206 views
Designing a PI controller for my power system
I have a power system which is given as:
Using MATLAB, I found the system's response to be:
As you can see, the system is not stable. So, I need to design a PI controller, so that, the transient ...
3
votes
2answers
85 views
Connecting powered digital IC to unpowered
I have Atmega328 MCU and MAX7219 connected to each other. However, they have diode separated power sources. There is a case, when MCU will get power, but MAX7219 will not.
Would it damage MAX7219? ...
0
votes
2answers
131 views
Easiest / cheapest way to build a dc power supply in the 150VDC range
I am looking to build a power supply to power a 150 V DC armature motor that will pull a maximum of 4 A. The cheapest I have seen so far is the following on ebay.
I'm looking to build one myself but ...
3
votes
1answer
167 views
Separating USB/MCU power buses
There are two power supply sources in the following diagram - USB and 12V. Only one power supply can be connected at the same time. I am trying to disable power to ...
-1
votes
1answer
115 views
Amplifier Vpp calculation [closed]
If you have an AC input and you want to amplify its amplitude, you have a DC power supply = x Volts , you know the load resistance R, you want to find the maximum RMS power you can get at the output ...
2
votes
1answer
67 views
Keeping a TVS diode biased continuously?
Quick question: Does operating a TVS at or above its "rated" (1 mA) voltage damage the device over time, as long as it doesn't get appreciably warm?
Background:
I'm driving some pretty hungry motors ...
1
vote
1answer
222 views
How can I model this linear power system in MATLAB?
For my power system, let us suppose it has the following dynamic model: \$\ x ' = f(x,u)\$.
This dynamic model consists of four first order differential equations (see below).
Then, I linearized ...
0
votes
1answer
109 views
Suitable wiring for very low current mains equipment
I'm building an interactive portrait gallery with seventy portraits, each back-illuminated by an LED lamp. The lamps draw less than 30 mA at 230 Vac, and each is switched using a small ...
6
votes
2answers
127 views
1N4001 Diode Heat
I'm working on a battery powered circuit that is using a 1N4001 diode to bring the 6V from 4xAA closer to 5V as well as for protection in case the batteries are put in backwards.
The total circuit ...
2
votes
2answers
124 views
Need help designing a custom box
I am doing a hobby project and I don't know much about engineering; therefore I decided to ask pros.
I have a 12v electric device that runs on Car battery only and I need to make it work if there is ...
