Tagged Questions

An electronic device which supplies electrical energy to a load. Can be AC or DC input. Typically DC output.

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0
votes
1answer
13 views

Connect / disconnect USB while external power source remains connected

I have some arduino mini pro collecting environment data, so they operate a long time collecting and I need to connect Gnd - Rx - Tx once in a while to transfer data to my PC, and then disconnect. I ...
2
votes
0answers
36 views

What is the lowest noise power source?

In particular two cases. 1) Unregulated: Supercap versus battery. 2) Regulated: Best regulation method to power precision low current analog circuits again with battery versus supercaps. I know ...
2
votes
1answer
47 views

How to use CR2032 in parallel with a power supply?

I have devices that is powered by a coin cell battery, but occasionally they fail and I would like to run them in debug mode to find the problem. Debug mode requires more power than the coin cell can ...
1
vote
0answers
48 views

Most efficient way to generate 5.0 and 13.25 volts out of 2xAA

Working on an instrumentation device for some friends' lab. The MCU and most of the electronics require 5V @ ~15 mA, and 13.25 volts need to be fed to one side of a differential unity-gain opamp. The ...
1
vote
0answers
43 views

Calculate number of LEDs, and resistor values, when some is turned on/off from time to time?

The LEDs that I have available is 3.2V ~ 3.4V and 20mA (exLED 5mm LED). (i'm planning to use the clear ones). The resistors is 1/4W metal film resistors (1/4W Resistance Metal Film Resistors). And ...
1
vote
0answers
26 views

Beaglebone black 3v3 rail

I am thinking about building an IO board which sends data to a Beaglebone black via SPI bus. In order to avoid the issue here, I want to just use the 3v3 pin supply to power the IO board so whenever ...
0
votes
0answers
43 views

Using a LM1875 instead of a LM675 for virtual ground

I've been gawking at the data sheets of these two, and I don't see any great disadvantage in substituting the TI recommended part (LM675) for the audio part LM1875 in this application (virtual ground, ...
2
votes
1answer
64 views

Power supply overshooting during power up and power down

My programmable power supply project in progressing slowly and now it's time to do something with overshooting of linear "postregulator" during power off and power on. Overshooting on step response is ...
1
vote
1answer
53 views

Dual Power Supply Switch?

So the question is short, how do i connect a single switch to a circuit that has a dual power supply (+/-) connected to it? Or do i have to use an special kind of switch?
0
votes
1answer
115 views

What kind of “locking” barrel connector is this?

I am looking for a replacement for a barrel connector; this is a locking connector (PN: PWRS-14000-260R for a Motorola FX9500 RFID Reader Country of origin: CHINA) however the locking 'fins' (for lack ...
0
votes
0answers
15 views

Rigol command to find if channel is enabled and max voltage/current can be applied

Hi I'm using RIGOL 832A in lab I just want to know if there's any command which returns answer 1. If channel is enabled? 2. Max voltage that can be applied to channel 3. Max current that can be ...
0
votes
0answers
40 views

Cheapest 120 volt offline power supply [on hold]

I'm working on a project which requires 120 V to 3.3 V, 300 mA power supply. I was just going to do the standard transformer,rectifier bridge, 7805 design, like I would have done 20 years ago, but ...
0
votes
1answer
81 views

What common factor could be causing wrong voltage on both rails of this PSU?

I'm trying to figure out why the 43/-43V rails in this PSU are actually reading 41/-41V. I'm presuming that it must be due to a single shared component that is out of spec, but I'm not sure what. I ...
-2
votes
0answers
30 views

Can someone please tell me what size barrel connector tip is needed for Sprint Airave 2.5 signal booster? Thanks [closed]

Can someone please tell me what size barrel connector tip is needed for power-supply for Sprint Airave 2.5 signal booster? Thanks
0
votes
0answers
56 views

Which logic gate arrangement would be better?

I have converted an old ATX PSU to a portable power supply for traveling as it is reasonably small. To go with it I will also make up a visual indication as to the state of the PSU once on, this is to ...
2
votes
3answers
332 views

Up to ~1000 A constant current supply 10-40 VDC

So a little background to explain the need. Occasionally we need to test starter motors (for engines) and provide enough power when the load (engine) causes the starter to pull in excess of sometimes ...
0
votes
1answer
37 views

UPS makes sharp short-circuit sound when close to full depletion [closed]

I'm using a 1500VA Xpert UPS which supports my CPU (Cooler Master's GXII Pro 750W power supply) and Monitor (ViewSonic VA1703wb; 21W). The problem is that when the UPS is depleting (AC ...
2
votes
1answer
67 views

Building a wall-wart style case

I'm working on a project that will plug directly into the wall outlet, similar to a night-light or a wall-wart power supply. Internally, I'll use a AC-DC converter like this one. It has built-in ...
3
votes
4answers
119 views

How do you calculate the power factor of a power supply?

Is it possible to measure or calculate the power factor of a power supply without using expensive tools? If so how?
0
votes
2answers
58 views

Can I use lithium coin cell battery CR2320 for discharging about 80 mA at 3 V?

I need to use a coin cell battery as a source for supplying 3.0 V at about 70-80 mA for about 2 hr per day. The coin cell battery I want to use, its spec sheet doesn't tell me much about what I want ...
0
votes
3answers
98 views

48V DC Power Supply Using LM7812 in Series

I want to create a 600W 48 VDC power supply with input taken from the line (220VAC) and so far the steps that I've had in my mind are: Stepping-down the voltage to 15V using transformer with 3A ...
0
votes
0answers
52 views

How long will my ~20W device last with a 18000mAh battery?

I have a Mac Mini with a max power consumption of 85W but an average power consumption of ~20W (in my experience). I'm thinking of buying a portable power source with a 18000mAh battery. How do I ...
0
votes
1answer
32 views

Minimum limit for current and maximum limit for voltage while calculating power

I have a brushless Motor then i am using in conjunction with a ESC, powered by a Lithium Polymer Battery(3S 1300mah). I just got a new Lithium Polymer battery (6S 15000mah) from a friend and am ...
1
vote
2answers
52 views

Set ground reference of a 5v DC power supply to the middle of a 24v DC power supply

I have 2 isolated AC/DC power supplies. one generates a regulated 5 volt power supply and other generates a 24 volt power supply as you can see in the picture below: I also have designed a circuit ...
0
votes
1answer
44 views

Use DALI interface to power the device

I work on a DALI lighting system for home usage and I design all DALI devices from scratch. In this system, also a sensor module will be implemented. Since it will draw only a negligible current (app. ...
1
vote
3answers
171 views

Why can't different current sources connect in series?

I've posted different question similar to this, yet still struggling to understand the theory. So here is another attempt to understand as to way two power sources(with different currents) connected ...
-1
votes
1answer
50 views

Multiple power sources, each for a certain purpose? [closed]

In a circuit, there is somewhat of a symmetry of power sources being connected together. If they are of equal voltage they would be connected in parallel increasing current at the same voltage. Or if ...
0
votes
1answer
32 views

Can you use a SPST to turn on and off two power sources?

I have several batteries in series and the ground point is in the center, such that I can achieve a negative and positive voltage. The OP amp uses both negative and positive voltage. Let's assume I am ...
1
vote
2answers
100 views

Dual power supply without center tapped transformer

I am building a simple bi-polar power supply, that will be capable of -/+12VDC at around 1.25A. I have a mains transformer that brings 230VAC down to ~20VAC, with single windings on both sides. And I ...
-1
votes
1answer
77 views

Need to make a laptop charger [closed]

I am not an electrician. My laptop's charger burned when we had high voltage 2 days ago. My laptops charger says Output is: 19.5 V and 9.23 A. I am in a country that you can't easily find those kinds ...
0
votes
0answers
15 views

Charging batteries thru cigarette lighter [migrated]

The answer to this may be so obvious that I'm almost too embarrassed to ask; however, here goes: I have a high-end battery charger for my car which charges through the cigarette lighter receptacle. I ...
11
votes
2answers
832 views

What's the purpose of the full wave diode bridge in this DC-DC power supply?

In the following power supply circuit, there is a full wave diode bridge (full wave rectifier?) after the DC Input. I can see how we need a full wave rectifier after an AC input, but why after a DC ...
0
votes
1answer
60 views

Buck regulator AOZ1014 getting burned

I am analyzing a buck regulator circuit as shown in following figure. link for datasheet given here: http://aosmd.com/pdfs/datasheet/AOZ1014AI.pdf I have few queries in schematic: Q1. In above ...
1
vote
3answers
74 views

Connecting parallel DC loads

Consider the following power supply interface. I'd like to power a number [1,N] of bitcoin miners, 12V, 5A each one. question is: do red wires must be connected with V+ pins ? do black wires must ...
3
votes
2answers
152 views

12V supply to Vin Pin on Arduino

I'm trying to understand the following section of the Arduino Uno's schematic: (Here's a link to Arduino Uno R3 complete schematic) The Arduino's site recommends that Vin should be between 7 and ...
1
vote
3answers
64 views

Low voltage adjustable DC power supply (0.1 to 0.75V DC) @ 300 mA

I need to create an adjustable DC power supply that can output between 0.1 and 0.75V DC at 300 mA (possibly as little as 100 mA). My input voltage can be anything, including +/- rail. Currently I am ...
2
votes
1answer
59 views

Low voltage DC Supercap UPS Design

Most generally I'm looking to design a UPS for a low power DC device given higher voltage AC current, with storage handled by a supercapacitor, or a bank wired in parallel. For my specific case I'm ...
1
vote
1answer
48 views

Connecting analog power domains in the same chip in ICs (Integrated Circuits)

I have a following issue, which I didn't see in IC books: I would like to know if it is possible to send analog signals (sin waves) between two power domains in an integrated circuit. The issue looks ...
0
votes
1answer
74 views

Connecting potentiometer to an ATX PSU

I've got a 500W ATX PSU (more info about it here) and I would like to use it as a sort of bench power supply. I know that there are many guides about how to convert an ATX PSU to a bench lab power ...
0
votes
2answers
94 views

Bench power supply adaptation 13.8V min to 12V [closed]

I have a bench power supply, which gives a minimum of 13.8V with 20A. There is something to do for adapting this scheme to give a minimum voltage of 12V? The scheme is this one ...
0
votes
0answers
55 views

24VDC servo motor does not start

I have a 24VDC servo motor (servo motor specs) I want to use to move a small linear stage. The servo output is 20,6W. It requires 5000steps per revolution. I have the motor connected to a servo ...
1
vote
1answer
105 views

Generating a ±70 V supply for op-amp

I am using the LTC6090 op-amp (links to datasheet) to generate a high voltage, low current voltage. However I've never really done anything regarding DC voltages this high before, so I was wondering ...
4
votes
1answer
110 views

ATTiny project resets when plugging in phone

Project I'm not very experienced with electronics and microcontroller-programming yet. I recently (accidentally) bought a couple of ATTiny13A microcontrollers, assuming I could program them using ...
0
votes
1answer
76 views

Can We send data using exisiting power outlets in homes

I am trying to build a project in which I want to transfer data through existing power outlets in a home through power lines while simultaneously using those outlets for power supply also. My question ...
0
votes
1answer
50 views

High Voltage negative power supply from positive supplies?

How can I combine two identical 5KV 15 ma power supplies that each are set up to deliver 5kv+ with negative being ground, so that they will deliver TWO -5kv outputs (cathode) and the + (anode) being ...
1
vote
2answers
44 views

Convert a device that is powered by a 12V 2 amp ac-to-dc SMPS to a battery powered device

I have looked up my requirements in all possible sources (Google, StackExchange, DiY boards, etc.) but I have not been able to find a clear answer to my problem. What I have is a device that needs ...
1
vote
2answers
85 views

Switching between USB power and single alkaline battery

I've read the numerous other questions addressing this topic, but I'm not sure if any of them apply to my situation. I am designing a device that will run off a 3.0-3.3V supply voltage and draw no ...
1
vote
1answer
70 views

Power supply 5V

I need some help about choosing the best on board switching power supply that has the less electrical noise and longer life time between these schematics for a 5V 200mA board... Heating is ...
0
votes
0answers
49 views

How to read part number on a transformer? Inside Dell power adapter LA65NS0-00

I have a dell power supply that doesn't work anymore and am trying to salvage the parts: http://www.amazon.com/LA65NS0-00-Dell-Inspiron-notebook-Adapter/dp/B00115AOTA There's a transformer in here, ...
0
votes
2answers
59 views

Any simple power supply designs for a 24VAC transforrmer?

I'm a beginner in Electronics Engineering. Any suggestions on simple power supplies with PCB designs which are run by a 24VAC transformer? Thanks!