# Questions tagged [power-electronics]

Refers to the conversion of electric power by using solid state components such as semiconductors. Can also generally apply to the field of electrical engineering which works with power electronics.

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### three LT1764A in parallel - what's wrong?

I've bought a lot of LT1764A LDO. To get more current, I've put 3 of them in parallel as in the schematic below. According to LTspice simulations, there should be at most 1.5V voltage drop whenever ...
118 views

### Electrical measurements of Chicago substation from where can I get it? [closed]

I am doing a project on electrical load prediction using machine learning. Machine learning involves creating models based on past data. For creating these models where can I get data regarding ...
164 views

### Heat dissipated by inverters

I am part of a team designing an electric car and we decided to use a bldc and I need to decide to use square wave or a sine wave controller. Since we have a cooling issue I must know which type of ...
61 views

### Raising Power Factor [Lagging] Using Resistive Loads

I am wondering why to bother myself and go look for capacitors to raise pf (lagging) while I can do this by just using more resistors in the load. Yes, as it might appear to you, my idea is math ...
866 views

### Why does a wind turbine deliver reactive power to the grid during no winds or when turbine is stopped?

An answer to a previous question explained that a turbine in stop mode may deliver reactive power to the grid. It also takes active power from the grid to run its control system, lighting system and ...
954 views

### Is it possible to replace a ceramic capacitors with two electrolytic capacitors in this configuration?

simulate this circuit – Schematic created using CircuitLab I would like to place a non-polarized capacitor in between V1 and R1. Is it possible to replace the non-polarized capacitor with two ...
78 views

### How is this equation valid? [closed]

I am trying to understand the Howland circuit.But how is the following equation formed .Isnt it should be(vi-vo)/R
273 views

### Majority Carrier Devices

Why majority carrier devices have higher ON state resistance compared to the ON state resistances of minority carrier devices?
88 views

### Do I need the same capacity connector on neutral side as on the live side?

This is basic question but I will ask anyways. Our real case scenario is similar to the drawing below. Lets assume 100A is flowing into the circuit that means 100A enters the circuit, gets divided at ...
300 views

### Can we use super-capacitor/s as a Vin input of the voltage regulator instead of DC power supply? [closed]

I do not want to use a battery in my circuit. My circuit would contain some charged super-capacitors and voltage regulators.
125 views

### Op Amp breakdown

I have read many datasheets of different types of op amps but non of them mentioned the breakdown voltages. For instance, when using an op amp as a comparator, what is the maximum input voltage one ...
3k views

### Want to run a Speaker/Amplifier combo from a rechargeable battery [closed]

I want to run KRK RP5 G2 Studio Monitors off battery for at least 1 hour. These are a combination of speakers plus amplifier in the one unit with AC power input. I do not want to use car battery ...
91 views

### Sensor damage, ground loop or something else?

We are testing an capacitive fuel level sensor in field. Its mounted on top of a heavy construction vehicle (colmar) with a 24v battery system. Our sensor runs for few weeks and damages. Every time a ...
116 views

### DC 12 V to 2000 V circuit

I want to design a battery operated pest trap (electrocuter). So far I have found out that the electrocuter snaps the insect at about 2000 V when it completes the circuit by landing on 2 nearby wire-...
395 views

### BOOST CONVERTER Simulation Problems in Multisim

I am trying to simulate a boost converter to step up the voltage to 70V from a 40V source on the Load resistor. Based on the formula: Vout =Vs(1/1-D), i calculated the duty cycle to be 42.85% however ...
122 views

### How to start a cage induction motor when load torque is greater than starting torque? [closed]

How to start a cage induction motor when load torque is greater than starting torque ? Please help me with this problem.
131 views

### Do PCBs have schematics? Revision [closed]

So the responses I received about schematics for PCBs were about what I expected. I have a reel to reel recorder from the 1960's that was my grandfather's. Inside is a complete schematic for the ...
91 views

### Replacing UPS of a CPU with whole home suppression (undervoltage) system [closed]

I need a new UPS however the knowledge acquired in the last years is preventing me from getting one I live in a large city (127v), and voltages rarely go above 130v, however it has happened at least ...
544 views

### Which one is the primary and secondary side of this Transformer

I found it on a old laptop charging adapter. I what to know the primary and secondary side of this transformer. It has total 8 pins. Each side has 4 pins
87 views

### Superposition Theorem Question

Calculate I' in figure 8-14(a) I need help on finding I' RT= 1/4+1/4+1/2 = 1 RT= 4+2+1=7 Then i applied ohm's law to find the current IT=14/7=2mA Am i calculating anything wrong?
510 views

### Multiple 7-segment displays connected to P1 of AT89C51

I want to connect three 7-segment displays on port-1 of AT89C51. The display unit has to show some number count. My question is: What should be the refresh interval for TDM signals on this port so ...
718 views

### Reasons of more than one ground pin in L293

Why in L390 they provide four pins for the ground and the heat sink? For heat sink,is only one pin is not sufficient? Here is the datasheet http://www.ti.com/lit/ds/symlink/l293d.pdf
58 views

### Can Lead Acid and Lipo batteries be connected together to achieve higher resulting current?

I have a lead acid battery setup which has 3x12V 12Ah batteries connected in series resulting in 36V 12Ah output. I also have 3 LIPO batteries (1x11.1V 3300mAh, 1x11.1V 3000mAh and 1x12.6V 4500mAh). ...
58 views

### How could i calculate the voltage induced in a detector circuit by picking up RF signals from a Mobile phone?

Is there any formula/equation i could use to estimate the voltage induced at the input from the RF signals?
93 views

### Do electronic devices require more current when alkaline batteries goes low?

I know that alkaline batteries' voltages go down when they're at low charge (from 1.5V~1.7V to 1.0V). For typical electronic devices like remote controls or bluetooth mouses/keyboards (that uses two ...
78 views

### Electric Vehicle Charging [closed]

I have a few queries related to EV charging: (1) When we refer to 'X kW' charger, is it that the charger is taking in X kW power and delivering power = X kW times the efficiency of the charger to the ...
147 views

### How the does this circuit source 4-20mA?

In the circuit, how the mosfet flow the 4-20mA based on the resistor network?
124 views

### Can I recharge 3.7v 150mah 30C battery using TP4056?

I think, I need to replace R3 (1.2k) with 10k of TP4046 micro USB module. Then I will get 130mA. Is it correct?
2k views

### How to measure RMS value of voltage using CRO?

I want to measure the RMS value of voltage of half wave and full wave rectified sinusoidal wave using CRO itself. How do I go about it?
199 views

### Should i replace a 13.5-0-13.5 2.5A volt with 12-0-12 3A or 15-0-15 3A? [duplicate]

Should i replace a 13.5-0-13.5 2.5A transformer (seems to be a custom made ) found in a chinese home theater with a 12-0-12 3A or 15-0-15 3A .Which would be better ?.Any suggestion would be great. ...
224 views

### What transformer to use for supply 9V to 8 5V relay connected to arduino mounted on a PCB? [closed]

I want use this transformer to power Arduino which will control 8 5V relay. I'm overwhelmed by variety of transformers. Here are few points/question I have in my mind. I need small transformer as I'...
123 views

### Switching between 240 VAC and a DC power supply using a 5V TTL pulse [closed]

So I have a 240 VAC (single-phase) mains source, and I'd like to design a circuit that switches between that and a DC power supply upon receiving a 5 V TTL signal from a delay box. Basically this ...
328 views

### Half Bridge Driver shorting the output of the circuit

This is a follow up question for this first one. Please read the original question before proceeding. I'm making all wiring on a bread board. At the output of the inductor (from the previous question),...
2k views

### can i step up Current [duplicate]

I am New in Electronics. I have 2 solar cells each one is 6.5V 20mA can I connect them to a device that takes 12V 0.5A? and what happens if I connect a device with power source output Ampere less ...
147 views

### Get 12V from normal PC UPS to supply low-power devises, such as Arduino [closed]

I have an UPS, there is a battery 12V, is it ok to use directly out from the battery (12volts)? The reason because I have an extra one, and want to supply some small devices, for example an Arduino.
531 views

### sensing the existance of the AC power line [duplicate]

I have more than one AC power source and I want to detect which one of them is ON which one is OFF using a Microcontroller. So my question here is what is the cheapest and smallest in size method to ...
116 views

### How to design an efficient high power bilateral switch for this special purpose? [closed]

I need to design a system that equalizes the two capacitors on each side. There are two big capacitors in the system and they will be charging and discharging by out of the system. They might reach to ...
96 views

### Can we control our computer's USB port? [closed]

what i want to do is : I want to connect a USB fan to my laptop and through programming want to turn on and turn off the fan. Is it possible to do so? Please post your valuable suggestions.
122 views

### Cumulative LEDs

For a better explanation let's think something like an equalizer bar Think one of these bars. The coloumn has 16levels from bottom to top. If the level 10's led need to light up then, the all levels ...
164 views

### Direct Torque Control of Induction Motor (DTC)

I was working on a project on how to design a classical Direct Torque Control drive DTC but there is a ceratin point that i can't understand. How can we calculate the Reference values of the torque ...
108 views

### Rogowski coil with magnetic core

is it possible to use a rogowski coil with a magnetic core? ie i want to integrate the output of such coil rather to place a resistor on it. so, what is the differences between it and a current ...
1k views

### What is the resulting RF power of the forward and reflected power if a Transmitter is operated into an open or short?

If I have a 25 Watt Transmitter that transmits through a switch into an open and/or short, what power would the switch experience assuming loss-less transmissions lines and switch?
607 views

### What is an impedance in AC circuit? (Preferred simple answer) [closed]

Can someone please help me understand what an impedance in AC circuit, please? I have read so much about it still I having time understand it. How does it affect the circuit, is it good or bad for ...
228 views

### Boost /step up converter efficient and very small for high current ? (with example)

Here you have a view of the external battery of Energizer (XP18000A) of 18 000 mAh. Energizer allows DC 19V, 3.5A in output : 19*3.5 = 67W There are 2 batteries, so 2*3.7 = 7.4V then batteries allow ...
670 views

### finding Q point of thyristor drive circuit.

how to find Q point of the transistor shown in the image. the problem is specifically due to pulse transformer.
255 views

### How is voltage gain typically achieved?

Excluding opamps and other IC's, how would one go about replicating a low voltage wave into a high voltage one?
22 views

### How to adjust the switching speed of Totem-Pole Bridgeless PFC? [closed]

How can I vary the switching speed of the totem pole PFC? Increasing the MOSFET gate area can vary switching frequency of the MOSFET. So does it mean it also vary the PFC rectifier switching speed? ...
207 views

### Boost converter control in DCM

I am trying to find a reference where a boost converter is controlled in discontinuous conduction mode (DCM) with constant duty cycle and by changing the frequency of operation. More specifically, I ...