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votes
2answers
304 views

Protecting fpga / ram against mistakes

I'm looking to build a board using a xilinx xc3s50a fpga and using a static ram chip of some kind. Perhaps something such as the GSI Tech GSI71116A. My worry is about the data lines of the ram chip. ...
1
vote
1answer
443 views

12 volt H-Bridge for a 2 volt motor

I designed an H-bridge that must operate off of 12 volt supply, I have a 2 volt motor I need to power, I was wondering with the TIP120 and TIP125 VBe drops of 5 volts each that it would operate the ...
7
votes
2answers
3k views

Servo Motor Won't Turn Without Push

So, please forgive me for the naiveté I'm most certainly going to exhibit here. I'm mostly a software guy, so this project is a little out of my comfort zone. Nevertheless: Project I have been given ...
5
votes
5answers
16k views

LM317 to create constant current of 2mA?

I have a circuit where I want to have a constant current of 2mA through a variable resistor. I've been told that I could probably use a LM317 as a current regulator, with one resistor on the ouput. ...
3
votes
4answers
4k views

How often does “bit rot” occur?

I have been thinking about the permanence of information lately and I was wondering at what rate a bit on a consumer spinning disk hard drive is corrupted and what are some factors that speed up or ...
7
votes
2answers
693 views

Oscillator Driven LED - Not Oscillating

I have an IR LED which is switched at a rate of 32.768kHz from an oscillator circuit (relevant portion shown below). I have 10 prototype PCBs. 30% of them work while the others don't. The problem is ...
1
vote
1answer
883 views

Coupling electret microphone input to linear audio output

I have two SIM900D module which have linear audio output and electret microphone input, and I want to connect audio output of one module to audio input of other module and vice-versa. The input and ...
1
vote
2answers
2k views

Current source with pulse option

I am seeking a very fast (10nsec rise time) transistor based fixed current source that I can use with my CPU. The CPU will use the GPIO to turn on or off the current source. This will be used to ...
2
votes
2answers
2k views

SMPS minimum rating / type calculation - how?

Looking for some help in defining the specifications of SMPS required to power an embedded project around (rather surprisingly, may be), Intel Atom motherboard. The plan is to run the system fan-less (...
0
votes
1answer
9k views

Voltage regulator or resistors to change voltages for motors?

After doing a little research I found out that I can change voltage by either using a voltage regulator chip or resistors. I have a couple different scenarios in which I'll have to drop the voltage ...
-1
votes
0answers
211 views

STM32 and embedded linux? [duplicate]

Possible Duplicate: Linux on ARM Cortex-M3 series Friends, Any ideas on how to use embedded linux into STM32 system ? Any shares or experiences will be very appreciated, Thanks
5
votes
4answers
3k views

What's this special type of PCB prototyping board called?

I'm trying to buy some prototyping boards for basic, learner electronic hobby project building, but the ones I'm seeing are merely grids with a separate and distinct via for each independent hole. I ...
1
vote
1answer
672 views

How do you output a frequency/note with a 1V octave keyboard controller?

To be specific, I made this: from here And to test the CV output, I used this schematic: from here It works as a oscillator. Every time I hit a key it will oscillate at that note, but it wont stop....
1
vote
1answer
2k views

Solid State Relay two switch based on headphone audio output to control dc signal

Need to turn on an LED if there is any audio present out of the headphone jack of a cell phone (0.6v peak voltage). If there's no audio, need to turn off led. My plan is to hook up audio signal to the ...
3
votes
1answer
1k views

DVI Shield pins

Should I connect the Shield pins 3, 11, 19, and 22 on my DVI connector to GND on my PCB? What consequences might I expect if I leave the shield pins floating?
5
votes
3answers
306 views

How are new 'best performance in the world' devices measured?

Say you build an ADC or a DAC (or a scope/spectrum analyser) that has the best performance in the world. With what exactly do you test it with? I'm guessing: Build the best ADC. You'll get digital ...
3
votes
2answers
183 views

Express bytes over cat5e as energy?

I'm interested in this purely from personal interest, I'm not a student. Can I express 1024 bytes of information travelling over cat5e as joules (or some measure that fits into energy of e=mc^2 )? ...
1
vote
1answer
3k views

Hybrid phone echo cancellation circuit

I'm using a single board computer to talk on a phone line through two coils, one for the TX part, the other for the RX. The phone line is on another coil and then it's connected to a two-wire circuit ...
0
votes
1answer
304 views

Passive Sign Convention

Sorry, I know this is a very basic question, but I've already searched a few universities' sites and through my books but none of them are giving me a direct answer. If you specify the terminals that ...
3
votes
2answers
34k views

Reusing Webcam and Monitor from old laptop

I asked this question on SuperUser.SE, about reusing the webcam and monitor from an old laptop (motherboard died). Following a suggestion there, i posted this question here. I found out a question ...
2
votes
3answers
2k views

How to connect GPS module to usb cable

I need help with connecting this module with USB cable or serial cable. What do I need to connect? What channels? EDIT: Okay guys I see that you think that this gps in not so good. How about this ...
1
vote
3answers
5k views

Sourcing slim 3.5mm stereo jack plugs [closed]

I'm not sure if this question is appropriate for the forum: I'd like to make up some male to male stereo leads with a 3.5mm jack at each end. The only assemble-yourself ones I can find are pretty fat. ...
1
vote
3answers
719 views

Problems starting PIC18F4680

Well I finally decided to get familiar with PICs and got myself a PIC18F4680 and a clone of PICkit 2. I made a simple hello world circuit as shown here: So basically I have an LED from port A pin 0, ...
-2
votes
1answer
2k views

How network card uses electricity? [closed]

I've read that NICs (Network Interface Controller) send and receive binary data as pulses of electricity, light, or radio waves. The NICs that use electricity to send and receive data are the most ...
2
votes
2answers
4k views

Recommendations for converting 2~7V to 5V?

I'm looking for a switching regulator chip (buck-boost, sepic, or other topology) to convert 2~7V input to 5V. I realize it's easier to have an input voltage range that's consistently higher or lower ...
3
votes
2answers
1k views

In general, why do capacitors have a higher tolerance than resistors?

In general, why do capacitors have a higher tolerance than resistors? Capacitors have a tolerance of around 10%-40% while resistors have smaller tolerances generally. Why is that?
3
votes
1answer
2k views

Is there an IC that inverts DC==>AC at the resonant frequency of a tank connected to it? (~50V ~40A)

Assuming I used the word "tank" correctly (something that has a resonant frequency) I have been working on a circuit that has 4 leads--two for DC input and two for AC output--such that you can attach ...
1
vote
2answers
383 views

Powering Nerf Gun With Wall Adapter

I have the Nerf Stampede gun that i am planning on making an automated turret from and need some help running it from a wall adapter, so here is where i stand: The gun normally requires 9V (6 ...
0
votes
1answer
389 views

How do I get 15V from a 34V power supply?

I have an audio amplifier with a regulated power supply putting out around 34V DC. I would like to add a preamp which requires on 15V. How would I draw 15V from the main power supply?
2
votes
2answers
3k views

H-bridge ic for high voltage and/or current

I tend to design my circuits around H-bridges, but the problem with making them out of standard mosfets is that I always have to compare the rise times, fall times, threshold voltage, etc of my n-...
2
votes
1answer
2k views

1-Wire bus implementation in PIC18F series for Parallax ColorPAL #28380 sensors

I've bought a Parallax ColorPal 28380 color sensor, http://www.parallax.com/Portals/0/Downloads/docs/prod/sens/28380ColorPAL.pdf In the documentation above, they've used a Basic Stamp ...
0
votes
2answers
2k views

Switching RCA composite video, under uC control - circuit ideas & suggestions

Trying to use Arduino TV-Out to switch feed to a TV set, s.a. ones found in Clinics, to display some information, s.a. next patient, expected delays etc. The TV is normally playing regular programming ...
4
votes
1answer
2k views

Eliminate 2.4GHz (Wifi) signal on power lines

We a designing a small pcb where a temperature sensor is placed close to a add-on wifi module. The sensor has four traces connected to it power and i2c (3.3V, gnd, SDA, SCL). The sensor needs to ...
5
votes
2answers
628 views

Choosing a Tantalum based on Min. ESR - LDO Stability

How does one go about choosing a capacitor for a LDO regulator which specifies a min. ESR? Capacitor datasheets that I've seen only contain the Max. ESR parameter. One could just choose a cap with a ...
6
votes
3answers
4k views

Setting pin to high in function instead of main, not full voltage output?

I have a function which turns on a LED by setting PB1 to HIGH. The light from the LED is barely visible. If I set PB1 to HIGH in my main function the light from the LED is as bright as it should be. ...
5
votes
3answers
6k views

DIY 130kHz RFID antenna design for reading tags in large area

I need to construct an antenna for a reader that will pick up a 134.2 kHz RFID tag. The antenna will need to be in "tunnel/culvert" under a road. The tunnel is 2 metres wide, so antenna needs to be ...
0
votes
1answer
1k views

Unstable oscillator using dsPIC

I've built up a small PCB with a dsPIC33FJ128GP804 microcontroller and a 7.3728 MHz crystal, among other components. While testing it last night I had no problems at all getting it working. It fired ...
0
votes
1answer
2k views

Battery powered light curtain of 100-150 LEDs

I have a hobby project of putting together a light curtain of 100-150 LEDs (3V, 20mA). It is meant to be used in an event outdoors without mains power. It could be operated with bunch of ordinary ...
0
votes
3answers
4k views

Arduino Wireless USB Cable [closed]

I am new to both arduino and electronics. Where would I start making a wireless Aduino USB cable. Which readings or websites can I go to for more information? PLease help...:) This cable should be ...
8
votes
2answers
2k views

Is there only one SMBus on PC Motherboards?

I have connected two wires to the SMBus clock and data lines of my motherboard (manually soldered via wires, because there is no header). I wish to interface this bus to my microcontroller. I hooked ...
3
votes
2answers
597 views

Why does design_vision compile my carry-lookahead adder into a ripple-carry adder?

At my school we have Synopsis "design_vision" in the computer labs. I don't know how to use any of the features so to me it's just a schematic-drawing tool. Out of curiosity, I hand-coded in Verilog ...
3
votes
1answer
215 views

Explanation of touchpoint density in touchscreens

I'm looking at touchscreen supplier specs such as this one. What does the specification "touchpoint density" expressed as touches/sq.cm sq.in or mean? The value given is "> 100,000 touches/in^2". ...
0
votes
1answer
171 views

Finger movement detection devices

Let's consider a device such as a game controller or a standard remote control, but which is not controlled by "standard" keys. Instead, the idea is to minimize finger movement, such as in a keyer. ...
3
votes
1answer
359 views

Smallest touch that can be detected on smartphone touchscreens

Not sure if this is the right place to ask this question, but what is the smallest touch (in terms of height and width) that can be detected on most smartphone screens (capacitive touchscreens found ...
4
votes
2answers
17k views

How to build an external lithium battery pack for a laptop with 19V DC input?

I'm trying to figure out how to build an external battery pack for a laptop, plugging into its 19V DC input. In a previous question I learned that I probably want to go for 5 lithium cells in order to ...
1
vote
2answers
2k views

How can extend the cable distance from a condenser microphone to the ADC without loosing fidelity?

I am new here so please forgive me for a vey basic question. I have a TASCAM iM2 in my possession. This is a stereo condenser microphone coupled to an ADC that connects to the the latest iPhone models ...
0
votes
1answer
1k views

How might I wire a split pi converter to transistors as to maximize output voltage?

I was looking into various dc-dc converter designs, and I was interested in the split pi converter. As a start, I just want to maximize the output voltage. I know in theory, the output voltage could ...
4
votes
2answers
750 views

What are the effects of connecting an external battery pack to a laptop's power jack?

I want to make a very simple external battery pack for a laptop, connecting to its 19V DC power jack. I plan to use a series of four lithium batteries that should provide between 11V and 16.8V of ...
4
votes
3answers
2k views

Why is a transistor used in a night sensor circuit?

The following circuit is often used in introductory (high school level) physics courses to introduce transistors or to give an example of why transistors are useful: Is it correct that one could ...
2
votes
1answer
1k views

Is it possible to use the Microchip Graphics library for a Single Color GLCD?

I didn't seam to see the controller for those simple GLCDs on the list of controllers for the microchip graphics library. Does it support such libraries, or do i have to create a custom controller to ...

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