# All Questions

5 views

### KiCad: Component outline on the soldering pad - will it disturb the soldering process?

Lots of KiCad's SMD components (including capacitors and resistors) print the component outlines over the solder pad. The pictures are shown below, please notice C25-27, R5-6 and D2-3 PCB design ...
8 views

### 4-pin quartz resonators - shall the 2 ground pins be connected to ground plane of the pcb?

I am about to use a 8MHz quartz resonator that has 4 pins (http://datasheet.octopart.com/LF-XTAL026380.-IQD-Frequency-Products-datasheet-6993.pdf): pin 1 and 3 are connected to resonator while pins 2 ...
8 views

### Correct Part for Connect an Two-Pin LED or Switch

Quite simply what I'd like to know is, what is the technical information for the male connector that corresponds to the following plug: The male connectors (headers?) are commonly found on computer ...
14 views

### Voltage to current ratio in a circuit

How do I find the ratio $${V_0\over I_s}$$ in the following circuit? Thanks!
7 views

6 views

### Torque measurement of induction motor

what device should be used to measure the torque of 3 phase induction motor? The motor is of 3000 rpm or greater
12 views

### BJH H-bridge going in reverse but not forward, LL transistor overheating

I've built one of this BJT H-bridge to control a DC motor in an old R/C car of mine, but I'm having problems with it and wanted a few tips to help me debug the board. The motor is a 2-wire DC with ...
33 views

### How do I work out what temperature to use when desoldering?

I have a temperature controlled soldering station, and know that I need to set the temperature appropriately for soldering based on the solder I use when soldering, but how do I determine what ...
37 views

### external watchdog reset for AVR required

I had a circuit with atmega644PA and use internal watchdog timer to bring the controller from a hang state to known by a reset. but still my code gets hanged in ...
14 views

### Accelemetor wifi module

I'm looking for a module that sends data from an accelerometer over WiFi. I looked around a bit and found this: Axivity-WAX3, but this was the only module I could find, and the site doesn't provide a ...
39 views

### Horrible noise after plugins power to my laptop plugged into effects chain

I'm using some stompbox effects with my guitar. I'm comparing them with my laptop where I have few VST effects. Everything sound clearly until I plugged power supply to the laptop. Then horrible noise ...
79 views

### Can I use digital pots for my feedback resistors to a buck-boost regulator?

I'm working on a design, and this will be my first attempt at a buck-boost regulator. I need the output to be variable because my application calls for different voltages under certain conditions. ...
46 views

### DC motor starting and stopping

I'm powering a motor, and instead of rotating at a constant rate, it rotates roughly a third revolution every half second or so; the rotation keeps starting and stopping. There's no load on the motor, ...
81 views

### How does this prototyping style work?

I'm a little puzzled about a prototyping style I've seen used recently. Here is an example picture of a circuit made in this way: Can someone explain the process of making a board like this? Why are ...
35 views

### Alternative to TPST Shift Registers?

So I'm building a musical sequencer that uses a shift register to close relays and pass the discharge pins of three 555 timers through a manual switch and potentiometer (acting as a variable resistor) ...
41 views

### Electronic package dimensions and what they mean? [duplicate]

In the image below I assume the three values given are max, typical and min. millimeters? When adding this part to a PCB library I assume I should use the typical values and the PCB layout should most ...
41 views

### D/A converter with 0.4 up to 4V voltage output

I have this circuit: I want to have as output: BCD Voltage 0 0.4V 1 0.8V . . 9 4V My circuit actually doesn't work correctly.
34 views

### Weighted Total Harmonic Distortion

What does make difference between a WTHD and a THD from practical point of view? Where and when the WTHD is more prevalent than THD?
33 views

### L293D outputs different in different motors. Are there different types of DC motors?

I recently picked up a used Spider King RC toy from a thrift shop (http://amax-toys.en.alibaba.com/product/337890538-212191267/rsc_9021_RC_Spider_King_car.html). It had no remote or battery charger ...
37 views

### The relation between light electric field and light power (optical modulation)

I have been keeping thinking this question for one week. Hope could get some help from you. Light 1: Electric field = $\text{e}^{j\omega t}$; Power = $\frac{1}{2}A^2$ light 2: \\$ \alpha = ...
32 views

### Measurement of frequency domain ripple of a filter

I am trying to analyze the passband ripple of various filter designs. I would like to know the correct way to measure the ripple. The trivial answer is to find the min and max amplitude in the ...
56 views

I am trying to interface my MSP430G2553 launchpad with an LCD but my characters look weird. I am using http://www.fibidi.com/arduino-lcd-16x2-characters/ with one potentiometer , with changing ports ...
63 views

### __What is this? [on hold]

(I'm not sure if this is the right site for this question, if not, please move it to the appropriate site.) -- So I was visiting a friend earlier at his condo and while I was walking up the stairs ...
78 views

### Identifying a transistor marked “N 842”

I have this transistor and cannot find its reference/datasheet. I've tried some variations of the name but nothing showed up. I know it is not an unusual model because here where I live we only find ...
78 views

### Will this motor controller take more motors?

If I was to connect two motors in parallel instead of just the one motor it currently has on each H-Bridge,, would the transistors on the motor controller blow? I have this motor controller - here is ...
38 views

### Switching regulator for 40~80V

If I have only +-5v source, can I boost it up to +-80V ? If possible, can you recommend a part? If not possible, how should I combine multiple booster to make it to high voltages. Thanks
45 views

### Thevenin equivalent circuit of a battery

I am a newbie to electronics so I need some help. I was reading about Thevenin equivalent circuits and I am pretty confused. I have the question like this: I have a 2V battery which draws a maximum ...
50 views

### Converting Short circuit solar cell (5v to 50mA)

How to convert solar cell short circuit current to Voltage. Because i need to display it to a 10bit micro controller. The voltage must within 0-5V. I'm using a 3V 50mA (max output) solar cell. ...
42 views

### Combination of four half-bridge load cells

I have a kitchen weight scale containing four half-bridge load cells, each cell associated to one foot of the scale. I want to hack it to use it as a pressure sensor and link it to an Arduino ...
39 views

### Adding indicator LED to optointerruptor circuit?

This question relates to my earlier question on how to wire an optointerruptor:Figuring out wiring of optical encoder I was able to get the optointerruptor working using the circuit below. I wanted ...
74 views

### Can you make an FM transmitter that will broadcast on the entire 80 to 108 FM band at once? [on hold]

I've been looking for an answer, a circuit, a pre made or kit that will do this. I want to transmit an audio music signal with a 1 to 5 watt FM transmitter that will blanket the entire 80 to 108 mhz ...
18 views

### Panels Voc exceed my MPPT charger limit, can I divide my panel to charge 2 different batteries? [on hold]

My solar panel's open-circuit output is around 154 V under standard conditions, my MPPT limit is 150 V. My battery pack is 60 V. Now can I divide my solar array into 2 parts such that they have VOC's ...
32 views

### LPC FMC to FPGA pin mapping on the Zedboard

Does anybody know anything about 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 ...
75 views

### Linear regulators overheating

I´ve designed and built a small board for supplying about 2A at 12V (regulated) from a 18V unregulated wall wart for a project of mine. It uses two LM7812 linear regulators to supply 1A each to ...
44 views

### WiFi Direct vs Bluetooth

I'm designing a device that needs to interact with smartphones and I need to choose between WiFi Direct and Bluetooth for communication. I don't need high speed, while a higher coverage would be good. ...
44 views

### Connecting multiple 4051 muxer into one pin Arduino Uno

I'm trying to connect multiple 4051 muxer into one pin. I've connected my circuit as below. As you can see, my circuit consists of one master muxer which is connected to the analog pin 0 and ...
56 views

### Variable power source from an ATX power supply?

I have an ATX power supply (400W) and I want to use make a variable power source for 3-20V using a LM317. I know that the 4 pins connectors (like the ones for the IDE devices) are +12V|GND|GND|+5V, ...
27 views

### Rotation-switched active rectifier idea

Most of you will know how three-phase rectification works and how cool it is. My idea is: replacing the diodes in a three-phase full-wave diode bridge with MOSFETs, as in active rectification, and ...
60 views

### Why do library book detectors make my headphones buzz?

Whenever I enter or exit a library while wearing headphones (cheaper intra-aural type), I hear loud buzzing as I pass through the book detector gate. I can vaguely speculate at a high level that ...
126 views

### I do not understand what power actually is

I realize this is probably a super common question, but I have to put it in my own words. I try to understand ohm's law with the water analogy. Two tanks with water, one with a higher level than the ...
55 views

### Breaking an LED off a PCB - can it be done? [on hold]

I bought a portable humidifier from CVS, and it has a SUPER bright LED inside. I've taken it apart and wrapped it in electric tape, and the tape has muted the light, but not 100%. Maybe 80%. It's ...
76 views

### Driving high-powered LED with demanding requirements

I have just purchased this impressive looking 100W "7-band" LED multichip, apparently it's the latest innovation. My problem is the chip's voltage demands are far lower than what ordinary 100W drivers ...
39 views

### Single Phase Sine Inverter

Can somebody tell my why that gain and integrator (and negative feedback gain) circuit is used to measure the current? This is the basic H bridge circuit, mosfet is used as switch here, and gate ...
56 views

### Can I use 100μF and 47μF as input and output capacitor, respectively, for regulator LM7924CT?

I have one LM7924CT regulator, but only have 100μF and 47μF capacitors at hand, can I use them? Would 47μF be too large for the output capacitor?
80 views

### When a pin needs to stay LOW or HIGH, is it okay to connect directly to VCC or GND?

For example, I'm using an Exar Exar SP3220EBCY-L RS-232 transceiver and the typical application loop back test shows that the EN pin is connected to GND and the SHDN pin is connected to VCC. Should I ...
36 views

### STM32L-Discovery programming on Linux with Eclipse

my problem is following. How to configure Eclipse + ARM in order to code for this microcontroller? I installed Eclipse and ARM plugin for it but I can't understand what to do after that :(
114 views

### VGA Decoding - Dealing with tolerances

I am making a VGA simulator or virtual monitor because Xilinx takes too long to synthesize VHDL (on my pc, and in general for large projects). With this VGA simulator, I can just run my testbench ...
23 views

### ATXmega: DMA and USART communication

I am working on an application on an ATXmega256A3 for measuring data. Ideally, the application would be able to communicate cleanly via UART with hardware handshake measure just in time even if ...