Questions tagged [power-supply]

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

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160 views

Why is this boost converter circuit outputting a lower voltage than expected? [closed]

I'm working on a boost converter board to power an OLED display, specifically a Midas Display MCOT128064SV-WM, off of 5V USB bus power (the VBUS pin on a Raspberry Pi Pico powered via USB). I ...
-2 votes
3 answers
147 views

Why can't we use DC lines close to ground instead of overhanging AC lines for powering trains? [closed]

Wouldn't it be easier to have DC lines running along side the tracks and have some sort of roller contacts (if the lines are flat and the rollers are spring loaded) or brushes connect to those DC ...
-1 votes
3 answers
67 views

Do active filters exist that don't cause a voltage drop?

Pretty much all filters I have come across always cause some sort of voltage drop. A passive example is the classic RC filter, an active example is the capacitance multiplier (which is basically just ...
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What are the advantages of a series emitter follower circuit for power supply?

I saw a power supply made of many series emitter follower circuits. The input voltage is about maximum 480VAC. I understand the circuit of single emitter follower power supply concept, but I don't ...
0 votes
1 answer
50 views

What capacitor do I need for an AMS1117-3.3 regulator?

I want to use an AMS1117-3.3 regulator to power an ESP32D chip that will consume 1A. The regulator will be powered by a 5V 1A supply. 5V at the regulator input to 3.3v at the output. How many ...
0 votes
1 answer
98 views

Current consumption by a solenoid valve

I want to calculate the voltage drop in a circuit loop consisting of a solenoid valve. The valve power consumption is 16W. The valve datasheet mentions minimum voltage to operate as 18V. I have a 24V ...
1 vote
2 answers
107 views

Automatic voltage selection using SPDT relay

I'm working on a design with two voltage inputs and I need to give priority to one of the two inputs when both are plugged simultaneously. Both must also work individually. the first input (V1) is ...
0 votes
1 answer
38 views

+/- 12v supply for AD8421

I need +/- 12 Vdc power supply for AD8421 from 5 Vdc. Can I use LT3582 (with output +/-12 Vdc; 85 mA) to supply the AD8421? Thanks.
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1 vote
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Motors' current exceeds adapter limitation

I've been playing with a motorized IKEA Bekant table and made an Arduino-based circuit to control its brushed DC motors via Pololu DRV8874. To my surprise, the regulated power supply reports ~3.5 A ...
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2 answers
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finding replacement for resistor labeled as fuse in schematic

I am trying to find a replacement for what appears to be a burned resistor in a power supply unit. It appears to be labeled as "F3" on the PCB which is the designation for a fuse. As far as ...
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2 answers
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Importance of power factor [closed]

I understand the difference between reactive power, but why is power factor so important? A system with low PF draws more current; well wouldn't a larger load, be it resistive or reactive, draw a ...
2 votes
3 answers
172 views

How to power two ESP-01S chips from 220 V AC [closed]

I would like to supply power for two ESP-01S microcontroller chips. I am a beginner with such kind of circuits. There are some constraints: The only available power source is 220 V AC, so I need an ...
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1 vote
1 answer
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Specify and connect one power supply for two applications

I have a 1980s chess computer to which I have added a Raspberry Pi 2 Zero to provide display and speech capability via a Python. It all works via serial messages and the only electrical connection ...
2 votes
2 answers
124 views

Are op-amp (LM324) power rails physically connected to their input terminals?

I have an AC voltage sensing circuit which uses an op-amp circuit with a LOC110 linear optical isolator. The left-side op-amp is powered by a supply voltage derived from a different AC source (an ...
11 votes
4 answers
1k views

Powering and dimming a few hundred light bulbs

I want to power a very large light fixture: it has 273 G4 socket light bulbs. The bulbs I found for the thing are 12 V 5 W ones, incandescent. So the question is how to power the beast (as it is 1365 ...
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-1 votes
1 answer
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Coupling 2 buck converter's output to increase output current

I'm quite new working with step-back converters, and I have to use them in the project I'm currently working. My board will have 24V/5A source input, and I want to step-down this tension to 12V, 5V ...
6 votes
3 answers
352 views

Why does a flyback converter in DCM mode have a different oscillation waveform at start and end of MOSFET turn off?

As seen from the waveform, when the MOSFET turns off, it has some high-frequency oscillations (shown in red) whereas before MOSFET turns on it has low-frequency oscillations. I have found that the ...
-1 votes
3 answers
65 views

In a DC power-supply design, is it safe to connect the GND of the secondary side of the transformer to the AC input part?

This is a design that my colleague was using to supply power to some op-amps in an accompanying AC voltage measurement circuit. I'm wondering why the ground of the secondary side of the transformer (<...
1 vote
3 answers
63 views

Rectifier circuit behavior - Need an intuitive understanding

Case1: OUT Series res = 10 ohm -> spiky input current reaching upto 15 A -> capacitor charging fast After a long time: Case 2: OUT series res = 100 ohm -> almost sinusoidal input current ...
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1 vote
1 answer
97 views

High side n-MOS driver without charge pump

I couldn't find details of this circuit configuration in an internet search. Most online results are about P-MOSFET in high side path or N-channel MOSFET with charge-pump/IC based driver. simulate ...
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0 votes
0 answers
56 views

How to calculate waste heat dissipation from a DC-to-DC-to-DC conversion

I am wondering how I can calculate the total combined heat dissipation (in watts) by two DC-DC converters in the following scenario; In my case, I have a project where I have 12 volt DC, which gets ...
1 vote
1 answer
43 views

Power supply switching off and on again after load drop

Context: I'm trying to automate my plants watering. For this, I'm using an arduino nano, 3 moisture sensor and 3 pumps. To separate the power (pumps) and the control (arduino output), I'm using S8050 ...
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0 answers
72 views

Help with power supply ORing circuit

I'm checking a system that has an ORing circuit to allow a battery backup for when the power supply is cut and it seems like a MOSFET (Q3) is backwards of how it should be. Vin=3.9 V (at LM66100), ...
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8 votes
1 answer
649 views

Why does a full-wave bridge rectifier have noisy output with no load?

Purely academic question: I have a little bridge rectifier made out of four 1N4001 diodes, being fed by a transformer putting out 12VAC. When I run it without anything else attached to it, the ...
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-1 votes
1 answer
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Unknown DC power pin

I'm purchasing this power module: I don't know what is the NC pin. Any idea?
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1 answer
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CANBUS troubleshooting

I'm currently having some trouble communicating my motors to a Speedgoat real-time target machine. Setup: My current setup includes the Speedgoat IO691 (CANBUS) module (https://www.speedgoat.com/...
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3 answers
125 views

What happens if input current of 2A is given to a L7805 rated of 1.5A?

I have used a L7805 to regulate a 12V to 5V where the regulator is rated of 1.5A and the input that I am providing is of 2A. The regulator gets hot. The only solution I found is to increase the width ...
0 votes
1 answer
125 views

Why does voltage drop 50% only when using a small coin cell battery?

I recently made a small coin cell battery powered bluetooth board. I get full voltage when using a dev kits 3.0V output but only 1.5V when using a 3V coin cell battery. Circuit summed up pic below. ...
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1 vote
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113 views

Step-Up Converter Design

I am trying to design a step-up converter with the following specifications: Vin: 3.0 - 3.7 V Vout: 30 V Iout(max): 50 mA With such a high boost ratio, my calculated duty cycle would be ~92% which ...
0 votes
1 answer
87 views

Is anyone familiar with this 29 pin connection?

It is the output port of a power supply. Anyone knows what this connection is called and where to buy the right cables? If you've come across this, please offer some details. Thanks.
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2 answers
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What is this component in a power supply?

We bought a Cisco 6500 series 6 kW PSU and took it apart. This is a module connected immediately to the inputs of the power supply unit. Does anyone know what it does?
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3 answers
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What are the assumptions involved in below rectifier output waveform?

The below waveform shows peak current occurs at the instant when diode starts conduction. Why is the peak current not happening at the max input voltage point? Usually the rectifier output caps are ...
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0 votes
0 answers
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Suitable Replacement RIFA Capacitors for Apple IIE PSU

I have an Apple IIE that I'm trying to bring back to life and in my research, everything suggests replacing the RIFA capacitors in the power supply. I'm looking for suitable replacement RIFA ...
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0 answers
58 views

Identification of two terminal component with top marking ON B48 MPC

What kind of component is this? The PCB silkscreen says V1.
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2 votes
3 answers
276 views

Boost converter inductor calculation

I am designing a boost converter with the following parameters: Vin: 3.0 - 3.7 V Vout: 30 V (nominal) Iout(max): 10 mA Fsw: 600 kHz TI's application note has the following equations for boost ...
0 votes
0 answers
60 views

Power supply design issue

Hi! I have PCB with this schematic and when it's power on, output is 0 V. As I understand there is not correct connection for IC1 ground. So my question is how to make it work? C19 make short and ...
0 votes
0 answers
58 views

Pi Filter Design

I'm new to design, all the help is appreciated. I'm drawing VCC12V from a external board for this application. I'm facing issues of EMI/EMC and voltage level of VCC5V is not that stable as expected to ...
0 votes
0 answers
48 views

Creating a line level signal and DC power from a speaker level signal

I have a speaker connected to an amplifier with some wires that run through a wall. I may want to replace the regular speaker with one that has an integrated amp and takes a line level audio input and ...
1 vote
1 answer
71 views

What is Partial Pressure Resistance?

While trying to design a power bank circuit, I came across a handy SOC IC IP5306. Looking through its datasheet (available here), I found the term ...
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1 answer
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BQ51051B or BQ51050B communicate but won't charge

I was building this wireless IC charger using BQ51051BRHLR circuit and when I connected the coil to the transmitter the output on Pin Rect shows a voltage of 10 V but the battery won't charge. Here ...
-1 votes
1 answer
86 views

Is it safe to keep PS_ON grounded?

I want to disable the 'soft power off' feature of an ATX power supply. So I think of connecting PS_ON and GND with a tweezer and keep it. But when the motherboard wants to shut down and sends high ...
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1 answer
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50Hz "noise" on power or ground line of power supply [closed]

I have a power supply that creates a 50Hz sine wave when I connect my oscilloscope to it. simulate this circuit – Schematic created using CircuitLab This sine wave looks like this below. ...
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1 vote
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12V to 3.3V using LM3489

I ran into an issue with the LM3489 not actually attempting to switch the transistor at all. I'm not sure why it won't start up. PGATE sits at 12V, VCC and when watching it seems to make no attempt to ...
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Wire size: is a 16 AWG wire the same 3x 23 AWG wires?

I'm building an LED installation and I was wondering if I could use the cat6 cables I already have. I've calculated the needed wire area to be 16 AWG (D 1.4mm, 1.65mm2) (for 5 meters). Would this be ...
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1 answer
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Does a battery drain if used in series of a power supply to boost voltage?

If I place a rechargeable battery in series with an active power supply to boost the voltage, will the battery ever need to be replaced?
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Multiple power banks to handle temporary increase in power demand

I have 1 PoE+ (Power over Ethernet) port from which I need to power 5 Raspberry Pi 4s. The recommended power supply for Raspberry Pi 4 is 5.1 V / 3 A which gives 15.3 so 5 Pis will require up to 76.5 ...
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0 answers
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Wiring power to many LED Strands

I have read as many threads on this site and others related to this, but haven't found any that specifically answers my questions. I have about 20 WS2811 LED Strands. They are 12V and each LED uses ...
-1 votes
1 answer
51 views

12VDC 3500mA filtering, what are voltage regulators and capacitor values [closed]

I have a 12VDC 3500mA power supply and I would like to filter the outgoing voltage from any noise. My plan is a simple scheme: output from the power supply -> capacitor -> voltage regulator ->...
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1 answer
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ESR of aluminum electrolytic capacitors [closed]

Is there any way to calculate the ESR of electrolytic capacitors for high frequencies? In aluminum electrolytic capacitor datasheets, the dissipation factor is given with low frequency(100Hz-120Hz) ...
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3 answers
188 views

Long term issues with AC/DC converter in always ON application

We have designed an "always ON" electronic home automation device which goes behind the switchboard (inside the wall.) This is the first commercial product that I am designing, so bear with ...

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