# Tagged Questions

52 views

### Why does a voltmeter show voltage drop

Consider this circuit. What would I get if I measure over R1? It should be less than 12v, right? But then what volatage is LAMP1 running at? Is it still 12v, or is it the voltage I measured across ...
142 views

### Why does a voltmeter read lower across a load than across a supply?

From the Wikipedia article about series and parallel circuits: As an example, consider a very simple circuit consisting of four light bulbs and one 6 V battery. If a wire joins the battery to one ...
89 views

### Amplify DC voltage

Which is the best way to amplify DC voltage from 1.8 V to 3.2 V? 1.8 V is the output voltage of BeagleBoard-xM and is intended to be logic input voltage on ic TX2 encoder. Should I concern about ...
78 views

### Nodal analysis with two voltage sources

EDIT: I am not removing the linked question and redoing the question. How do you formulate an equation on a node with two voltage sources connected in it, regardless if it is a supernode or not? ...
80 views

### PWM motor controller to switch down voltage on a boat

I'm planning to use a bank of 4 x 12V batteries in series on my boat in order to provide 48V to power an electric DC motor. I also need 12V power for things like lights, fridge, etc. I thought of ...
135 views

### Behavior of capacitor with infinite capacitance at steady state (DC analysis & AC Analysis)

What is the behavior of the capacitor below at steady state (DC/AC Analysis)? simulate this circuit – Schematic created using CircuitLab
141 views

### Help with dropping voltage on 1000w dc power

I've been struggling for a few weeks trying to find a way to lower the voltage coming out of my new solar panel array (35V DC, 36amps, 960watts). I have an inverter that will not accept voltage over ...
192 views

### How to switch positive/negative voltage to positive voltage

I have DIY telephone line powered flashlight (similar to this post, but I have used LED strip). The positive & negative leads seems to get updated frequently. Since I soldered the leads to LED ...
168 views

### How to shift (-12v) - (+12v) to 0v - 24v? [closed]

I have a voltage (-12) - (+12) and want to shift this range to (0) - (+24). How can I do? Any suggestion, idea, circuit or... Edited: i'm sorry for delay. it's a signal. Actually the voltage of my ...
283 views

### What could happen if I plug into my Arduino an AC adapter instead of a DC one?

I´ve read that Arduino needs a DC adapter and not an AC one, I know that. What could happen if I plug into my arduino an AC adapter? I need to do a quick test with two small 4.5v DC motors, and I ...
255 views

### Why is a railway's third line or overhead line DC and not AC?

As the title states, in the rail industry, why are the majority of railway's third line or overhead line in DC volts and not AC volts? My initial guess would be that it is in AC since it is easier to ...
134 views

i've Speaker with woofer requiring AC 12 voltage, and i have DC 12 voltage Adapter. However, speakers are working properly. but Can i use DC 12 V Adapther with the Speaker which is requiring AC 12 ...
228 views

### DC 5V to 3.3V DC-DC Step-Down issue

TL;DR : The output voltage from my 5V DC to 3.3V DC stepdown seems to output 4.5V DC - why? Background: I'm trying to power an Airport Express from USB rather than a wall outlet. I have discovered ...
231 views

### Should I use multiple voltage regulators?

I have five devices that need to be powered. I would like to use one DC source to power the four devices. Should I use voltage dividers, voltage regulators or a mixture of both? Also, any ...
88 views

### Will a device capable of receiving a 200 Vrms input signal happily accept a 200 VDC signal?

To the best of my knowledge, Vrms is used to express an AC signal as the equivalent DC signal that would produce the same power dissipated in a resistor R; I believe this is best calculated using a ...
2k views

### Protect DC Circuit from too much voltage

How do I protect a 3v DC circuit from being damaged if someone accidentally plugs in a 12v power supply? The circuit will draw much less than 1 amp.
350 views

### Calculate power supply on distance

I need to provide 12V DC to a DC brushless motors that need 12V 30A at distance of 30m from the source. The cables I can us are 20 Gauge, I know that the cables are loosing power, how can I ...
1k views

### What is the easiest way to lower the DC output (reduce voltage)?

I have 13.5 VDC output, and i want to power up a small radio that takes 4.5 VDC. I thought about adding 5/6 used 1.5V batteries in series, so it would be about 4.5 VDC for radio and about 8 VDC for ...
5k views

### How does current flow through a voltage source?

Im going back to electricity 101 to understand several things Im missing. One of them is exactly how does current flow through a DC source. Heres my understanding: A voltage source is one which has ...
124 views

### Powering a fan with an AC adapter [duplicate]

Possible Duplicate: Choosing power supply, how to get the voltage and current ratings? I need to power this fan which is rated at 12 V, 0.95 A, 11.4 W. I am unfortunately without a DC power ...
129 views

### what methods could I use to step-up 700VDC to 5000VDC(approx)?

The input into my circuit is 5-15VDC; this passes through a digital potentiometer so that it can be controlled. Then there is a mini DC-DC converter which steps the voltage up to 700VDC. Now I need a ...
444 views

### how can I made a 12vdc to 19vdc booster/regulator?

This is a fairly specific question, but I think the answer could probably be applied to various voltages. I would like to make a circuit that will take in a 12-14volt source (from a lead acid) that ...
140 views

### Do I need to double the voltage with double the motors?

I am totally new to electronics. Let's say I am building a DC circuit with a motor using 6V taking 1.28A. Now, if I build a circuit that uses two of these motors, will I power the circuit with 6V and ...
13k views

### 230V AC to 5V DC converter, lossless

Is there any IC which converts 230V AC to 5V DC? As lossless as possible. I want to connect my microcontroller to an ordinary electrical socket and I don't have enough space available. Thanks.
150 views

### Identifying an irreducible circuit?

How would you go about identifying an irreducible circuit? By irreducible, I mean combining resistors whether in series or in parallel to reduce the circuit.
203 views

### diode nightmares

Let me start by saying I am a complete amateur trying to stumble my way through some pretty basic PCB design, and I have run into a problem selecting diodes. The PCB I am designing will be for some ...
2k views

### acceptable bounds for replacement DC adapter [duplicate]

Possible Duplicate: Chosing power supply, how to get the voltage and current ratings? I've got a broken gadget that is discontinued. The only thing broken is the power supply (verified by ...
336 views

### Voltage Limit of CAT 5 DSL wire

I have been using threads(single wire) inside CAT 5e wire in a project for providing input to the circuit and output to a telephone. The source is 50V DC but the input to my circuit is just 4.86V DC ...