# All Questions

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### How to amplify and offset the voltage in an opamp?

I need to amplify a voltage, which comes from a DAC and is 0-2.5V and scale it 0-25V in an operational amplifier. After amplified, I need to offset it -1.25V, so the final voltage is -1.25 to 23.75V. ...
48 views

### Difference between op-amp and MOSFET?

1.S An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. 2.S A transistor is a ...
5 views

### how does the iso work in ccd\cmos array detectors

I'm curious to know how exactly does the iso sensitivity work in ccd's or cmos detectors that DSLR cameras have? I understand this is a amplification of the raw signal that each pixel has, but is in ...
55 views

### RS232 and realterm communication problem

I am not seeing anything on a port in realterm though it is properly sending the data through the port. Anyone run into a similar situation? What am I doing wrong? I am using a C8051F120 developers ...
25 views

### Relevance of amperage in a voltage divider circuit

I'm not very competent on the electrical engineering, so forgive me if this is a dumb question. I'm trying to make a voltage divider circuit to monitor the battery level of a project I'm working on. ...
271 views

### Lower Vcc of power amplifier and still provides 30 watts

The above circuit is a power amplifier delivering roughly 30 watts (11.7V times 2.9A) in the 4 ohm load (assuming its a speaker). When we look at $V_{cc}$, it looks huge when compared to ...
149 views

### Circuit that measures the speed of sound in concrete

I need a circuit to measure the speed of sound in concrete to 1μs or better. This is for a school demonstration where students who study construction will use this circuit to measure the speed of ...
877 views

### Center tap vs. bridge transformer

I'm designing a power supply to deliver 6V DC with a zener diode acting as the regulator. I found out that there are two types of transformers that can be used. They can be center tap or a bridge. In ...
303 views

### Diode fails open

The question asked is the following: The book says that the correct answers are: $V_{limit}$ = 0V, $V_{diode}$ = 5V. I don't get why it ended up like that. My intuition says that, "fails to ...
200 views

### Amplifier capacitors

Why is that when I use electrolytic capacitors (the cylindrical ones) and measure the end with respect to ground, there is some DC voltage appearing (where in fact it should be 0 volts since capacitor ...
16 views

### Any more subtle alternatives for LED's to indicate status?

Is there a low-cost, less annoying alternative to a buzzer or LED for displaying the status of an operation? I want my clock radio on at night, but it has this really annoying power indicator LED. I'd ...
7 views

### Resonance factor of RLC circuit

Say we have a RLC circuit, connected to a source. Say, regarding to the positive side of the source, we have in order, an inductor L, followed by a resistance R and a capacitor C in parallel. So we ...
3 views

### Power rail design from Li-Polymer battery chip output

Case: I am building a battery driven device and so far it seems like I will be using the MCP73871 to provide my device with battery power and charging via USB. I need to regulate the output from the ...
16 views

### Am I forced to use a gyro and an accelerometer, to find a relative point in space?

I am quite new into the electronic realm, so forgive my lack of proper terminology. I am planning to build a simple device, that I will be use to manipulate a mesh on my computer. when I move the ...
27 views

### MPLABX + PICKit 2 programmer could not be started

I'm working on getting a basic LED flashing program loaded onto a PIC12F615. I'm getting the following error when attempting to read or write to the device from within MPLABX: The programmer could ...
323 views

### Simulating FPGA design without having the actual hardware

I'm new to FPGA and currently taking HDL (Verilog particularly) class. I have sufficient knowledge in digital design like combinational and sequential circuits. I want to create a project similar to ...
80 views

I have a solar-powered LED number display whose rechargeable batteries have apparently died. I'd like to hook it up to AC power using a 3V adapter (i.e., cutting the leads from the batteries and ...
9 views

### Emulating a USB Standard Downstream Port Charging application

I have am using an LM5017 to step down a relatively high voltage solar panel (VOC over 90V) to 5V. I have bench tested my circuit and it is providing good buck regulation with input voltages up to ...
10 views

### Convert a wired headset to a wireless one

new to the board and not caught up with current technology, but I can handle myself when it comes to soldering and small electrical appliances. I have a headset that I really love, but the wire ...
41 views

### What is the difference between a tuner and an antenna? [on hold]

I was just told by my TV's customer service that my TV had a tuner but no Antenna as a response to my question - Can I use my TV's inbuilt Antenna to pick up over the air channels? I was wondering if ...
5k views

### How do step-up transformers work?

I’m trying to figure out how a step-up transformer works. A step-down transformer is simple and logical enough; you start out with a higher voltage and end with less, the remainder being wasted as ...
7 views

### TI's bypass mode step-down converters

Texas Instruments encourages the use of the TPS62730 step-down converter with bypass mode along its RF devices. Does this mean : its noise is low enough not to affect RF ? Thus being a more ...
14 views

### Is it okay to rapidly switch on and off a DC adapter

I have a thermoelectric coller I've converted to a heater which I usually use a normal thermostat to control. I've just upgraded to a PID-based controller which of course is going to be switching ...
80 views

### Exposed Pad on a mixed signal IC, ground plane connection and power supply decoupling

I'm using a DAC with an exposed pad (NC) bottom. The datasheet specifies that the EP should be connected to ground ([EDIT]Presumably [/EDIT] for heat dissipation, but heat concern is not noted in the ...
1k views

### Designing a power supply (zener) to achieve steady 6V ($\pm$ 0.01)

UPDATE: My target is to obtain 6V as the voltage output. As you can see, it is 5.94 V. I've tried adjusting my variables, yet it varies from 5.6 to 5.94V, never having reached 6V. What would be the ...
338 views

### Class AB power amplifier

I have implemented a class AB amplifier. The schematics are below. As you can see, my $V_{cc}$ is only 1V. How come I can still suppy 2.8 amp to the 4 ohm speaker/load? Is it a bug in MultiSim, ...
785 views

### Powering an LED from RF (cellphone signals)

How can we design a cellphone detector similar to the one shown in the YouTube video, provided we set the following restrictions: purely passive, (no external sources like battery) power should come ...
24 views

### Adding braking to a H-bridge schematic

I followed this schematic to build an H-bridge: http://www.pocketmagic.net/2009/03/a-simple-h-bridge-design/#.UqjoLFXxteW Now, when I first switched it on, I was surprised that the transistors ...
69 views

### Why does this parallel->series rewrite change my AC simulation results a little?

Here are two circuits I've simulated. Both have a current source of $\sin(\omega t)$ mA with $\omega=1000$. They should be equivalent but give different simulation results. Here are the ...
227 views

### Operate a relay from HT12D's output

I'm using the HT12D remote control decoder (and HT12E remote control encoder) to send some data using RF and I have done so successfully. Now, I want to operate a relay depending on the output of one ...
38 views

### How to route a LVDS clock from FPGA input to output?

Using VHDL, How is it possible to receive a pair of LVDS signals (say external clock) on the FPGA and route them to another pairs of pins to go out, without any modification? I have tried IBUFDS and ...
24 views

### Crimper for Smaller Connectors

I need to grow past the 0.1in black headers for a current project. They're just too big. But I don't know of anything suitable as the next step. Low current carrying ability is OK (2A ideal, 1A ...
198 views

### Understanding Electrical Engineering with Analogies

Understanding concepts with analogies help can be a useful technique and hopefully this will help me better understand electricity and Electrical Engineering better. Lets start with a simple water ...
23 views

### What is the maximum magnetic flux density a HDD can tolerate before data is corrupted?

Does anyone have hard numbers explaining the maximum number of Teslas a hard disk drive can tolerate before data will be corrupted. This forum says "a lot", which isn't super helpful. This one ...
53 views

### TONS of adhesive on Blown capacitors. Try to replace or swap in NEW BOARD? [on hold]

I've read the HELP CENTER > ASKING page. Not sure where I stepped out of bounds in the original post, but I've reduced the content to the following in an effort to comply: At issue is the IP ...
31 views

### Need +9V power supply for breadboard (3x Stepper motors). Tried Arduino wall wart

I need to supply +9V to three stepper motors on a breadboard with driver carriers (see parts below). Its too much for my raspberry pi to handle, apparently. I was able to power and control a single ...
50 views

### DIY Drone helicopter communication [on hold]

I'm pretty new to electronics, though I know how to program. Have been playing with the Arduino UNO board, with success of some sensors and motors etc. My next challenge is being creating a drone ...
2k views

### How to find out if electrical outlet ground is working?

Just want to make sure my outlet's ground is working. How to do that? UPDATE: My main aim is to test resistance of anti-static wrist strap, but since I know it works by testing it with multimeter, I ...
55 views

### How can a logic gate work with multiple signals if a circuit only (supposedly) uses one electrical line?

On, say, a circuit for a lightbulb there's only one line for the current to flow, and that current is illustrated in every circuit I have ever seen. Being a beginner to this I am wondering how that ...
13 views

### Need an ADC with at least 3MHz and input voltage on the scale of 10mV

In short, I'm looking for an ADC that will be receiving a 1 MHz signal with a nominal voltage of 10 mV. In long, I'm setting up a theoretical experiment to measure the elastic modulus of an unknown ...
98 views

### Using a Zener diode to ease a voltage regulator

I was reading a tutorial on how to hook up a zener diode to ease a voltage regulator. Here if you follow this link, as one can see the zener diode is dropping some amount of voltage to ease a voltage ...
36 views

### Linux application for drawing electrical schemes (building plans & schemes and not PCBs) [on hold]

Can you tell me if there is any good Linux application for drawing electrical schemes & plans for buildings. There are plenty of applications like EAGLE or KiCAD which are only good for drawing ...
49 views

### How to map LPC FMC pins to FPGA pins on a Zedboard? [on hold]

How to map fpga pins to actual physical pins on the FMC connector on a Zedboard? Of course I have looked into the user's hardware guide and the master constraint file, but all I have found is a list ...
70 views

### Wood workbench as ESD protection?

ESD protection are really expensive for hobbyist like me. I have a grounded wrist strap but do you think a simple non-treated wood workbench surface can replace a really expensive ESD tabletop ?
35 views

### Why does the bandwidth of an OP Amp decrease as temperature decreases??

From this NASA article on figure 5, you can see that the bandwidth of the operational amplifier drops as temperature decreases.. What is the mechanism that causes the drop on bandwidth because as ...
29 views

### Amplify offset voltage

I have a signal that varies between 3 volts and 4 volts. Now I want to amplify that 1 volt difference to a range from 0 volt to 5 volts. I tried to find a solution with an opamp or a transistor, but ...
60 views

### How exactly does the CPU tell RAM what number it wants, and how does it then move that signal? [on hold]

Like when I say something like MOVE FROM RAM, 20 DEC TO A REGISTER, how does the CPU know how to get electrical current to say 20? Like, let me make this more clear for you... I want to move 8-bits ...
32 views

### OpenCV on ARM (Considering using X86 instead?) [on hold]

Im working on a little hobby project with plans on using OpenCV, preferably the Emgu CV (C# wrapper). I've got a BeagleBone Black running Debian Wheezy, but since its ARM based, ive had heaps of ...