Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [dc]

DC stands for Direct Current, which means the flow of electric charge in a single direction. Examples of a DC source are batteries, solar panels, dynamos.

0
votes
0answers
23 views

AC & DC Voltage source superposition theorem

My professor mentions in his notes that the voltage of v is 5 Volts at the capacitor However, I tried using nodal analysis on paper and my answer matched with the voltage shown by my simulation of ...
-1
votes
0answers
28 views

DC-AC circuits exercises [on hold]

I have some problems with electronics and I can't solve the two exercises below: the first one: and the second one: In the second exercise I managed to calculate (hopefully it is correct) that DC ...
0
votes
0answers
34 views

Pwm DC output smoothing

I'm in the process of assembling a big 25Ah 4S (16.8 v when fully charged) battery pack. The plan is to multi-purpose that to different DC output voltages so the PWM choice felt natural. Now I want ...
-2
votes
0answers
31 views

I need help in ac to dc variable power supply [closed]

I HAVE MADE A VARIABLE AC TO DC POWER SUPPLY 0-20V . I WANT TO MAKE IT FROM 5V TO 20V. HELP PLEASE AND DONT TELL ME TO USE LM317 OR ANY REGULATOR.
0
votes
1answer
18 views

Dimming LED with speed controller

I'm trying to controll 4 parallel 12V DC LED strips with an speedcontroller. I am able to dim the lights from 100% lit to about 5% lit, but it never turns them off completely. My multimeter can't ...
0
votes
1answer
53 views

Deal with DC offset

I have STM32 BluePill and Teensy 3.2 , they both read analog 0 < x < 3.3V. I want to read earphone microphone sound but the mic produce +-2.5V (with ~200mA, but this is a different problem). ...
0
votes
1answer
34 views

Controlling speed of 7 DC motors from Arduino 101 using PWM outside of the audible range

I am researching a way to generate PWM for 7 independent DC motor drivers, each connected to a 12 V DC motor. The drivers take in a PWM signal, a direction signal and a 12 V DC supply and use this to ...
-2
votes
1answer
45 views

Run a 12 dc power through telephony cable [closed]

I have a converter (120 AC to 12 DC) which is used for sending alert to outdoor through 30 meters telephony cable. My quistion is ( Is it harmful if someone touch the cable? the output can give up to ...
3
votes
8answers
3k views

54V 5A DC thru “regular” coax “TV” cable for use as a “poor man's” solar power cable?

In the effort of saving money without having to buy expensive solar cables (and because I have a lot of extra coax cable lying around doing nothing), I would like to use a piece of coax cable (that ...
0
votes
1answer
54 views

How to solve this circuit using KCL

I understand the super node aspect of this circuit, but I'm unsure of what to do as I dont see a direct way to proceed with KCL using all of the nodes. I found the equation for the supernode, but I'm ...
0
votes
0answers
30 views

Parallel DC sources with varying voltages

I have different DC sources which i want to hook up to a 24v battery pack. - Solar controller output - AC/DC charger - truck alternator Can i connect these in parallel? I've been told that because ...
1
vote
1answer
54 views

Synchronous generator induced EMF

I have started studying synchronous generators in more detail of recent and I'm finding it difficult locating helpful information regarding their operation. What is the formula that can be used to ...
0
votes
1answer
30 views

Dusk dawn motor driver with polarity reversal

I'm trying to accomplish this. When a dusk dawn switch is on, drive a small DC motor for a few seconds and then stop. when the dusk dawn switch is turned back off, then turn a small DC motor THE ...
1
vote
1answer
43 views

boost converter to high voltages (20kv+)

I am interested in making a mini, potentially portable ion thruster. The Question: Is it possible to create a boost converter that takes low voltage batteries ranging from 3.7V to 24V and boost that ...
0
votes
0answers
47 views

Circuit wont work with dc motor

This circuit wont work with the DC motor included but works fine with out it, what can I do to make it work? I need the motor to work when it receives the infrared signal, thanks.
0
votes
2answers
52 views

Brake DC MOTOR circuit

I have a DC motor that is controlled with an npn transistor with pwm. Everything works fine. I want to brake the motor instantly. I tried to short the terminals with another pairs of transistors but ...
0
votes
1answer
61 views

Power absorbed by load resistor

Can someone double-check where's the mistake? The system didn't accept my answer. TASK: Find the maximum power absorbed by the load resistor, knowing that: $$E = 6.6V; R_{1} = 12.1Ω; R_{2} = 14Ω; R_{...
0
votes
1answer
24 views

Using a x-speed transmission with a DC motor

I would like to ask whether there is any point in using a transmission with different gears (like the gearbox in a car) with a DC motor? For instance in an RC car. Are there any benefits to using a ...
0
votes
1answer
30 views

Finding indication of ideal ammeter

Would anyone share some tips, advices for solving this task? So far, I have dealt with far simplier electric circuit's tasks. This is new to me. Any kind of help or advices are appreciated, thanks!
0
votes
1answer
53 views

Difference between ideal and practical ammeter?

What is the difference between the ideal and practical ammeter? To be more precise, here's my task: I do not need a solution to this. Just looking for a clear explanation between practical and ...
2
votes
2answers
148 views

Replaced 4x AA battery with 6V 3A DC adapter, but device won't work

I'm hoping you smart folks can help me. I'm puzzled by what I thought would be a simple DC battery to DC adapter swap. The device I'm trying to mod is a a microchip activated pet door (SureFlap ...
0
votes
0answers
55 views

Using High voltage DC supply to bias an operational amplifier

I am using FS05CT-12 high voltage power source to bias PA91 op amp. Please see below for the schematic I am using. I want the op amp to be biased between ~±100. At input voltage 0.8V, the power source ...
2
votes
1answer
67 views

Sound sensor not working when connected to DC motor

I made a small circuit to control a DC motor with a sound sensor, using an ATtiny 85 and an L293D. It worked on breadboard, but now that I have a prototype PCB it ceases to work. Whenever I connect ...
0
votes
4answers
89 views

High frequency response of capacitors

I have studied the fact that the capacitor does not like a varying voltage across its terminals, and it acts as a short circuit initially so that there is no voltage drop across it. If this is true, ...
0
votes
1answer
39 views

NGSPICE dc simulation error

I want to do dc simulation of differential amplifier circuit, and this is my .cir file looks like: When i run simulation, ngspice give me an erorr: Supplies reduced to 0.1000% Warning: singular ...
0
votes
0answers
47 views

Can you power a chip that needs two voltages, from different sources?

I have this EEPROM chip that needs 5 volts for normal operation. But when it is getting programmed, it needs 12V on a different pin. Could I just use 12 volts from an external adapter, or do I need ...
0
votes
1answer
68 views

How can I build BJT amplifier with Vin and Vout requirements (peak to peak values)

I have been working on a project but I'm not sure if I'm complying with the requirements that I was given. Design a BJT amplifier such that VIN=0.1 V and VOUT=5 V (peak to peak values). ...
-1
votes
4answers
100 views

Controlling DC 90V motor with Raspberry Pi or Arduino

I have project where 90v dc rotating motors(4 of them) must be controlled via Laptop. What is the most simple solution, Can I go with raspberry pi or need to go lower with arduino or there are ...
1
vote
0answers
40 views

Isolated vs non-isolated boost converter for LED (12v to 24v)

I have a 12v system in my motorhome and planning on installing 24v LED strips, however, I'm unsure whether I would need an isolated or a non-isolated boost converter. I'll be using roughly 5 meters ...
0
votes
1answer
61 views

Differential transimpedance amplifier

I have found an opamp schematic that I don't understand. As far as I know a transimpedance amplifier "converts" my input current into an output voltage. But in this case the positive and the negative ...
0
votes
2answers
59 views

Is it possible to induce negative/positive charge wirelessly

Sorry if this question doesnt belong here. I have no clue of what I'm about to ask. I want to know, if possible, how to induce negative/positive charge on objects inside recipients? What I want to ...
-1
votes
2answers
106 views

What will happen if I powered a 24VDC device from a 27.8VDC power supply?

I have a device which has a power input from 12-24VDC Auto select and 250 mA load. I connected it with an online DC UPS which has an output of 27.8 VDC on grid mode and 24 VDC on Battery Mode. I ...
0
votes
1answer
33 views

How would I limit speed of dc motor being used as a generator?

How would I limit speed of a DC motor being used as a generator? For a project where I have to make a wind turbine that will automatically limit speed of rotation once past a certain value. Thanks :)
-2
votes
4answers
68 views

How to find max load limit in datasheet?

I have а datasheet but I don't understand: how to find max load limit in datasheet? Can I use this SSR to switch the load (12V DC), and what current can I count on? Thanks.
1
vote
1answer
89 views

Will an AC series motor work with DC supply?

I have read that a DC series motor can be operated using AC supply, but there will be excessive heating in the core and yoke and also a low power factor. So, construction is modified to have laminated ...
0
votes
0answers
22 views

DATAQ Data acquisition device power connector [duplicate]

I got hold of a DATAQ DI-710 data acquisition device. The device was delivered with an AC-adapter. According to the data sheet, the device can be connected to any 9-36VDC however. The only problem is ...
0
votes
1answer
127 views

What are the symbols in the picture?

Not brilliant pic but bigger picture from UK vehicle wiring diagram, windscreen wiper motor.
1
vote
1answer
56 views

How to solve a circuit network involving a resistor parallel to a voltage source using only nodal analysis?

I have been stuck on this for the past week and this week i just dont seem to find out what am i doing wrong. Please help me spot my mistake. Here you can find My circuit on multisim. Please provide ...
0
votes
0answers
16 views

Ideal voltage multiplier design to run a VFD from a battery

I'm looking to run an IV-21 VFD tube off of a low-voltage portable power supply of 4-8 VDC. I've been looking at various voltage multiplier designs to supply the higher voltage needed for the anodes ...
1
vote
2answers
59 views

Equivalent circuits with one or multiple resistors

I am designing a circuit but I am facing a repetitive design that require too many resistors. The problem comes down to answering if the next two circuits are equivalent in terms of voltage drops: ...
0
votes
2answers
51 views

24 VAC sprinkler valve using DC power

I am creating a circuit that includes a 24vac sprinkler solenoid. I need it to be portable so I'm planning on using DC current rather than AC. What is the best way to do this? If I just use straight ...
0
votes
0answers
28 views

Difference between 6v UB645 and 4AA

I'm just a hobbyist working on a prototype for a toy. I'm using one of the small 6v blowers typically found in mascot costumes (like the silly t-rex). It currently uses 4AA batteries but I was ...
1
vote
2answers
35 views

DC Motor Winding Insulation Material

As I understand it, the field coils and armature windings in a DC motor are insulated and this insulation can 'burn off' if the motor overheats, causing a short circuit to develop. What is the ...
0
votes
1answer
59 views

Op Amp as a simple switch

I want to build a little voltage switch that switches on a buzzer and a relay when a certain voltage is reached. Please have a look at the schematic. I use a trim potentiometer to set up the switch ...
0
votes
1answer
52 views

Separate two batteries getting charged by one charger with diodes?

I've got a robot that I use two batteries on. One of the batteries power the servos and engines and the other is for the digital boards. The servos need 5 V. The control board and LCD run on 5&...
2
votes
1answer
106 views

Function of the Third Pin Inside Laptop Barrel Connector

So I've been doing research on barrel pin connectors, and have been trying to apply this knowledge to understand laptop barrel connectors, specifically. My confusion relates to the function of the ...
-1
votes
1answer
48 views

stall dc motor 12 volt for long time

hi every one i make water cooling system for dc motor 12 volt how can i make the dc motor hot to test the system ? whan i stall the dc motor the wires get very hot before that effect the motor and i ...
0
votes
1answer
40 views

DC Battery Stability

I have a 12 V load that works by connecting an adapter from the AC socket and this adapter output 12v to the load. I decided to make a 12 v battery that can charged and the feed this load , all the ...
0
votes
1answer
46 views

Making a DC motor turn in saturation and cutoff modes of an NPN transistor

simulate this circuit – Schematic created using CircuitLab So I have a DC motor that should turn with light on LDR and should stop when I cover LDR or turn off the lights. Basically the ...
-2
votes
1answer
39 views

DC generating plant [closed]

What would happen if positive terminal of Dc get grounded in any DC generating plant? Will it impact negative terminal and burn it?