# All Questions

116 views

### Do I need to use thermals on vias for reliability?

This question is further to Why thermal reliefs on vias? I have recently been advised (by someone I consider an expert) that I should add thermal reliefs to vias which are connected to planes, even ...
35 views

### How to design a filtered power supply? [closed]

The filtered power supply that must be design can produce dc output voltages of +10V (+-) 10% and -10V (+-) 10% with a maximum load current of 50mA. The voltages are to be switch selectable across one ...
67 views

### Synchronizing SPI ports for higher data rate

I am designing a new board which uses the NXP LPC4330 (Cortex M4 microcontroller) with a XESS Xula2 FPGA development board. In this design, the Xula 2 has limited I/O pins since it is designed to fit ...
103 views

### Can I achieve a one shot button without a 555?

I have a complex circuit, but my problem only relates to one small part. I have a relay, which is energised by pulling the low side low using an NPN. I would like a pushbutton to operate the ...
80 views

### what is the gain of this amplifier at resonance frequency?

I want to analyze this circuit but I do not know how to compute its gain at the resonance frequency. In lab its gain at resonance frequency (910kHz) was 54.
194 views

### What's an easy way to supply power to a breadboard without using batteries?

There are a number of kits available (for example sparkfun's Breadboard Power Supply USB - 5V/3.3V and Breadboard Power Supply 5V/3.3V or Adafruit's Adjustable breadboard power supply kit - v1.0) but ...
76 views

### What kind of oscilloscope is good? [closed]

I want to buy an oscilloscope as a gift of Father's Day to my Dad. I have no idea what kind of oscilloscope is good? Is there any kind-hearted friend can help me? Thank you in advance!!! :-)
44 views

### Temperature sensor issue [closed]

I am implementing home automation using an MSP430F2274. For that I need to read a temperature sensor and send the values to the receiver side. Please suggest any manuals to write code?
37 views

I am a newbie to ethernet control operation using pic18f controller and dont know how to configure my Olimex ENC28J60-H Board with PIC18F controller using SPI communication. However i have written ...
34 views

### Kicad: How to add a Filled Zone around a Net with a single pin?

I am designing a PCB in Kicad and I need to add a filled zone around a single pin (pin needs to become part of the zone, not an island). For some reason, when the "Copper Zone" tool provides me with ...
66 views

### Is it possible to build a CPU from content-addressable memory?

Every modern programming language use objects and not C/C++ style struct/class. In C/C++ every data member has a size, so addressing a struct member is basically a memory address + offset. But script ...
71 views

### Speed control for high power DC brushed motor

I am going to drive and bi-directionally control the speed of some 12V/24V, 100W to 300W DC brushed motors. I have some experience in controlling small DC motors (6V/9V/12V, 0.5A to 2A) with PWM ...
52 views

### How to calibrate an optical particle sensor (Mie scattering)

I have a very simple sensor that basically emits infrared light (1 micron wavelength in the infrared range). The light scatters off particles whose diameter is of the same order of magnitude as the ...
206 views

### How does this circuit diagram work?

I don't understand this circuit diagram here, but I'm sure that you can help me out. I'll explain what I have figured out so far. EDIT: It's a metronome circuit. Sorry for being unclear about that. ...
177 views

### basic math question about voltage, ohms, resistance

total n00b here. After working on several projects by copy & paste from other people's schematics and code, I'm finally digging in and learning some of the math to know what I'm doing. If I have ...
47 views

### Non-clock signals routed into the clock tree

In my synthesis report, I see that several signals internal to the microblaze have been routed onto the clock tree. ...
35 views

### Digital Audio Filter: Delay, Echo, and Pitch Conversion [closed]

I'm using dsPIC Starter Kit (DM330011). And I want to put those three stuff as a main functions. Delay: when you speak on Microphone to record it and play it through speakers, hear your voice in 2 ...
77 views

### Custom USB Impedance question

I'm looking at making my own USB cable for a project. The primary issue I'm having is that I'm getting a lot of capacitance in my cable between D+ and D- (400ish pF) which is enough to throw off the ...
74 views

### Reason for certain steps in Circuit Analysis

The image is from this lecture.The instructor Prof. Shanthi Pavan says that the part encircled in orange can be replaced by a voltage source with current through $v_1$ as $i_1$ and not \\$i_1 + ...
61 views

### Providing DC power with failover DIY for IP camera

I'm building a simple battery backup box for a 5V IP camera. I've got a few options for battery, sealed lead battery or a mix of portable LIPO style "USB" power bricks. I've seen boards built for ...
98 views

### What is the minimum temperature for FR-4 PCBs?

My company is working on developing a product that will go into commercial freezers, so my boss asked me to provide operating temperature specifications for the product. I can find "operating range" ...
65 views

### Circuit Diagram Controller [closed]

I want to make a circuit diagram which will: Read the speed of a servo Divide the speed of servo With the result of the division will be controlled the speed of an other motor like this: Servo ...
54 views

### should I use 2 SPI devices on Arduino UNO/PRO or 2 I2C devices?

I am using a microSD breakout board and the accelerometer ADXL345 https://www.sparkfun.com/products/9836. each one alone works perfectly fine, but once I put both (sharing pins 11,12,13, but with ...
326 views

### why is wall voltage measuring 175V?

I was trying to use a DM-4100A multimeter to verify a power supply, and I'm not sure I'm using the multimeter correctly. The multimeter is >10 years old too, so maybe it is not working correctly. ...
49 views

### can power source damage electronics? [duplicate]

I think that this is a noob question but I just can't figure it out: I have 2 devices : First device working on 5V / 50A Second device working on 5V/ 30A I want to power them with power source : ...
75 views

### What do I need to know about leakage current?

I recently suggested a plan of removing one end of a resistor from a breadboard to remove it from the circuit in order to measure its resistance, but my mentor suggested that this won't work for high ...
24 views

### Asic Ideas (FFT, AES, Motion Estimation) [duplicate]

Could you give me a list of applications with kernels that can be accelerated in hardware? Some examples would include FFT, AES, Motion Estimation, Viterbi Decoder. I'm just looking for others. I'm ...
62 views

### simple h-bridge polarity reversal

I am trying to reverse the polarity on a rather beefy motor (5 amp, 60v) in the most simple way possible. I need to build an h-bridge just to reverse the current, I am controlling speed elsewhere. ...
36 views

### Independant Contractor Electro-mechanical assembly charges [closed]

I have the need for a higher-level assembly technician that can build brackets, standoffs, and cabinet hardware as well as make and solder wire harnesses to boards and connectors. What is the hourly ...
146 views

### Stability problem in unity-gain opAmp

As a part of a controlled power supply for hardware-in-loop testing for a student driven project, I had to develop a current buffer (voltage follower) which could source up to 1 A. I had the (bad) ...
128 views

### Good RS232-based Protocols for Embedded to Computer Communication

I'm working on a project that involves a good bit of data communication between a remote Arduino and a computer. The wireless connection is through a pair of XBees, so we have a RS232 link between the ...
72 views

### Compliance question

Q. You have +5 and +15 volt regulated supplies available in a circuit. Design a 5mA npn circuit source(sink) using the +5 volts on the base. What is the output compliance? This is what I've done: ...
105 views

### Power Supply Control Circuit

I have to build the circuit shown below as a homework, it is a power supply with frequent energy switching; but the schematic is incomplete... I should add another circuit which controls the voltage ...
49 views

### What type of AT commands should i use? [closed]

I want to display my location information from a GPS receiver to a personal website(or any other website) using a GPRS modem connected to an arduino board through a USB host shield. My problem is ...
47 views

### How does zero balancing work in an amplifier? [closed]

I'm using an industrial amplifier which has coarse and fine balancing. I uploaded the circuit picture and circled the fine balancing in red. I use it to zero the output(for offset). It is done by ...
61 views

### Applications with kernels that can be accelerated in hardware [closed]

Could you give me a list of applications with kernels that can be accelerated in hardware? Some examples would include FFT, AES, Motion Estimation, Viterbi Decoder. I'm just looking for others. To ...
99 views

### How exactly does switched capacitor system work, what exactly is the detail of the primitive that switches

I have been seeing these switched capacitor circuits for some time now and have even seen Z-transform being used to model how these circuits behave. While I can see that there is some capacitor that ...
49 views

### Should one use resistors to protect an mbed when using it to simulate keyboard key presses

One can use mbed to act as USB Host or as a USB Device. One use of the latter is to have it emulate a USB Keyboard by sending normal key presses. The general page on using mbed as a USB Device is in ...
51 views

### Make two bluetooth modules communicate directly?

Can one buy two cheap (and identical) bluetooth chips and make them talk to each other without needing a PC or a mobile phone? I'm guessing the answer is a basic 'NO', but I might as well ask. ...
142 views

### Is it better to have a poor top layer copper pour or no copper at all?

For a few small 2 layers boards I'm doing, I'm using the top layer for parts and signals and a ground pour on the bottom layer with no or very short traces, based on comments and answers to my ...
93 views

### Are additional smoothing capacitors required off of a voltage regulator

This is a subset of a circuit I am building to run motors off a PIC 16F884: simulate this circuit – Schematic created using CircuitLab I noticed last night as I was drawing up my ...
53 views

### Multiplexing with or without transistors

I'm doing something in where I need to multiplex 6 7-segment displays. About doing it, I found things like this: And things in where the same thing is done without the transistors, just by ...
40 views

### Problem with impedance matching on DIY 4 pole 3.5mm audio splitter

I built an audio 4 connector 3.5mm splitter. The goal is to play a sound clip through a phone's mic input across a call, while recording the same sound clip on the computer. I used the TRRS ...
36 views

### SD Comms Resetting Processor

I have implemented an SD/FAT combination on a Renesas RL78/G13 processor. The SD card is being driven using SPI. The code has been proven to work on two custom target boards using a 2GB card - the SD ...
72 views

### Microcontroller, ARM, and FPGA [closed]

I'm going to study Wireless Sensor Network. I'm looking for a good way for understanding micro-controller, ARM and FPGA: i mean books, free technical materials available on the web, like university ...
94 views

### What is important in computer clocks' signal: signal edges or intervals when signal is stable? Will multiple value propagation occur?

I am trying to figure out some basics of digital electronics. We have all seen the squared graph of the computer clock signal: I have read multiple articles on the Internet and still can't figure ...
99 views

### How good is coaxial cable?

My question relates to the accumulated AC voltage that will appear on the screen of a length of coax: If the cable is properly terminated at one end and fed with data (or any signal) at the other ...
50 views

### Convert between dBA, dBV and RMS values

How do I convert between dBA, dBV and RMS values? For example, I have used a current probe (clamp) with a gain of 100mV = 1A to measure a series of currents in dB and I would like to know the ...