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H: Reading a multibyte volatile variable that is updated in an ISR
Consider the Arduino code at the end of this post for full reference that makes LED13 blink in a 0.5Hz rhythm driven by timers. It is just a proof of concept, I know it can be improved for various aspects, but lets focus on the following issue. Althoug... |
H: Why is this BJT transistor saturated?
The bias point (without the 623mv input) is calculated as
\$I_b = \frac{5-0.6}{5.5 M\Omega} = 800nA\$
\$Ic = \beta I_b = 290*800nA = 233\mu A\$
These calculations checks out in the simulator.
But when I connect, the Input signal, whose peek is at 623mV, the transistor saturate... |
H: Is the LT8500 a current source or sink on its PWM outputs?
I am using the LT8500 as an LED driver and I need to know if the leds are current sink or source.
Also if I need to have resistors in serial with the PWM outputs since the output voltage is 4V.
I've looked through the whole datasheet and I'm not finding any... |
H: Why does a nonlinear system cause inter-modulation?
Can someone answer or point to a link explaining why a nonlinear system causes harmonics.
According to Wikipedia
... non-linear systems generate harmonics, meaning that if the input of a non-linear system is a signal of a single frequency, then the output is a s... |
H: Zener Diode - Vz0
Theoretically, what is the importance of Vz0 in the following figure. When modeling the zener diode, why is Vz0 used over the diode's given Vz?
For modeling, I was given the formula Vz = Vz0 + rz*Iz.
AI: There are varying degrees of accuracy that you can expect from a model. The simplest usable ... |
H: What is the purpose of D1 on the gate of the MOSFET? [NCP3065]
I've built this DC-DC LED Driver, and don't quite understand the purpose of D1. In particular it works with a 1N4007, but I wanted to replace it with a Schottky type for faster switching since the 4148 is much faster than a 1N4007, but the circuit fails... |
H: What does banking mean when applied to registers?
This answer to a question on StackOverflow about what banking means in the context of ARM's banked registers indicates that there is some confusion about the meaning of banking when applied to registers.
What does banking mean with respect to registers?
AI: The word... |
H: Charging lead acid (car) batteries with a common ground
I have three identical lead acid batteries. All three batteries are on a common ground since they power different components on a same circuit. I have three independent "intelligent" chargers whose charging outputs are on isolated grounds.
I wonder if there is... |
H: Flash and RAM : Code Execution
I recently started learning assembly and came to know about linker scripts and other low-level details of hardware programming. I am also teaching myself computer architecture and somewhere along the line I came to fear that my picture of the memory model might have been wrong all alo... |
H: The options for communicating sensor data in a medium size building
What are the options for communicating sensor data to a central point in a medium size building?
I want to build a cheap centralized temperature control.
In each room there are about 4 radiators which I want to equip with a few sensors like temper... |
H: Clean DC power design for very high precision circuit
We have been designing a very high precision control circuit for quite a while. And we are thinking to make it much easier to use, which is to get rid of the Lab DC Sources and use AC to DC switching power (get power from 220V/110V directly).
Our circuit runs a... |
H: How is the clock frequency established between master and slave in I2C protocol?
This is a follow-up question to What happens if I omit the pullup resistors on I2C lines?
In a digital wall clock I designed (using the DS1307 RTC and the ATmega328 MCU), I accidentally omitted the pull-up resistors that must be wired... |
H: What are the advantages of an ESC over a PWM?
I'm building an octocopter, and can't quite understand what an ESC (electronic speed controller) is used for. A brushless outrunner motor has three cables. Is there one common ground, one power supply (DC) and one cable to communicate with the ESC?
Does the ESC simply u... |
H: How to find cause of reset in PIC16F microcontroller?
I've worked with other microcontrollers that have a register that I can check on powerup to check a register that contains debugging information on the cause of the reset.
Initial searching revealed an RCON register that may not be available in my current PIC. ... |
H: Is there such a thing as a switch that can be actuated automatically?
I'm interested in a toggle switch that can be toggled without user input. That is, the physical state can be toggled electrically. It would need to incorporate some sort of motor or magnetic actuator. My google-fu is weak in this area, and I have... |
H: Differences in VHDL syntax
I'm reading a VHDL design and I came across the syntax in the architecture that looks like:
x_out <= x_in(15) & x_in(6) & x_in(19) & x_in(20) & x_in(28) & x_in(11) &
x_in(27) & x_in(16) & x_in(0) & x_in(14) & x_in(22) & x_in(25) &
x_in(4) & x_in(17) ... |
H: How to calculate power consumed by an electrical device in a specified amount of time?
Say for example I have a TV with "140 watts" marked on it. Does this mean the TV consumes 140W per minute? Per hour? Per day? How is the power consumed by device calculated from the device specification?
AI: If a car is travellin... |
H: TRUE/FALSE or true/false?
In resource-constrained systems (like an 8-bit PIC), is there any benefit to using your own macros for true and false as opposed to using those defined from stdbool?
#define TRUE (1)
#define FALSE (0)
// OR (dummy example)
#include <stdbool.h>
bool IsThisGood(void)
{
return true |... |
H: Discrete MOSFET Amplifier question: Trouble finding the Overdrive Voltage
I am working on an exercise problem (5.18) regarding Discrete MOSFET Amplifiers. I have taken pictures of the question material (Disregard the section under the question) and my latest attempt at a solution:
Alright. Keep in mind that the c... |
H: More info about J-link v8
I have a J-link v8 and want to use it, but I can't find its name in Segger homepage, I want to know what ARM core it support and is it support BeagleBone or RPi.
AI: The information you need should be on this page, the note at the bottom of the page refers to hardware revision 8 and up whi... |
H: Is "True RMS" applicable only to measuring AC voltage?
Higher end multimeters feature "True RMS" rather than "averaging" voltage measurement. Is this applicable only for AC voltage measurement?
AI: Usually only AC ranges, which are AC coupled so you lose the DC component of the signal. The reason why you would not... |
H: why do rechargeable batteries fail so horribly in high drain environments?
I've tried nicads and nimhs in flashlights and they always end up leaking. I know how spikes and memory work in such batteries, but why do such high drain applications cause such catastrophic failures in these batteries while alkaline batte... |
H: Hardware advice for simple wireless embedded application
Now, I am going to learn embedded programming in microcontroller. I am going to create a device that will receive signal from wireless transmitter. The range will be less than 30 meters. So, I have some questions about toolkit.
What type of transmitter and r... |
H: What components are these?
I usually buy electronics components at an online surplus store and they usually throw in the box some more goodies to pack what you order.
I bought a multi section plastic container and it was filled with all sort of components, and this one in particular intrigues me. Here is a photo:
... |
H: Arduino Pin value gets stuck
I'm using a Python program to send some message over serial port to Arduino. This message contains the pin number of the pin and whether it should be HIGH or LOW . Eg: Sending 2H\n should set pin 2 to HIGH.
pins array maps the pin numbers in the messages to the actual pin number of ardu... |
H: How to power up BeagleBoard-xM using batteries?
I 'm looking for a battery solution to power up BeagleBoard-xM. Until now, I used a 5 V, 3.2 A AC/DC power supply adapter (2.1 mm barrel plug).
I 'm thinking of using a 4 x 1.2 NiMH AA battery pack (or NiCd). This way voltage will be 4.8 V, that is the minimum -xM's e... |
H: Analog to 1-channel Digital Converter
I have 0-5 V analog value coming in, and I need to convert it to a high or low 5V digital signal. Essentially, I need to create a 1-channel A/D converter. The idea is that when my analog voltage goes above a certain threshold, it will set the digital output high, and vice-ver... |
H: Tying ground planes together with a non-zero Resistor
I was reviewing the schematic of a motor driver board and noticed that the digital and analog grounds are tied together with a 3.9 ohm 1/4 watt resistor. I am still trying to find the gerber files to see how the ground plains are laid out, but does anyone know w... |
H: Create a fake depth encoder signal on a surface system?
I am trying to create a test box which will do away with the actual depth encoder as it is awkward to have out all the time the encoder is similar to this: http://www.encoderonline.com/UK/Data-Sheets/Incremental/Data-MXE.htm
The unit it is connected to outputs... |
H: Sniffing a proprietary data line at 47.5V
I need to sniff the physical layer of a proprietary data line with a logic analyser, but my analyser is limited to 5V input. Unfortunately the line runs at 47.5V, which would fry everything. I considered a simple voltage divider, but I'm concerned that I might pump a lot of... |
H: checking uart overrun and framing error flags in linux
Checking uart overrun and framing error flags in linux.
In some microcontrollers I can access overrun and framing error flags programmatically. Is it possible to access these flags from command line?
AI: I've read and written to registers in the past by writing... |
H: How does this wireless transceiver work?
While messing with Arduino I came across this wireless transceiver. As a newbie in all this stuff, it's written that it operates at 2.4 GHz, so the transmitter crystal and receiver crystal must operate at 2.4 GHz, right? From the photo I can see that the crystal is 16 MHz wh... |
H: Adesto DataFlash (AT45DB641E) reads zeros after exercising flash for several minutes
I am using the AT45DB641B Adesto DataFlash and not in Low Power mode.
In my application I am recording a stream of raw sensor data and constantly writing to flash every second. I have a self-test that is invoked every minute to rea... |
H: How to optimise something when multiple parameters change the output
This dilemma seems to occurs all the time in so many different engineering problems. It seems impossible to optimise something with multiple parameters, for three reasons:
There are too many possible combinations of these parameters to be able to... |
H: BJT vs MOSFET failure modes
I know MOSFETs are much more efficient than BJTs in that they don't consume as much power when on whereas a BJT consumes base current the whole time it is on. I also know that MOSFETs tend to fail shorted. I can't find any information on BJT failure modes though/do they usually fail open... |
H: Control 12V MOSFET with 5V, with PMW pass-through?
I am new to electronics, and still tying to fully wrap my head around MOSFETs. I have a few questions about controlling a 12v MOSFET using only 5v to the gate, and an incredibly small amount of current.
Here's the situation:
I have a 48V power supply which I am con... |
H: Flash Programming for AT89S2051
Forgive me if this is a noob question, this is my first MCU project.
After reading a few tutorials here and there, I've set up my MCU circuit and programmed a simple program in Keil μVision 4 and compiled it to HEX-80. However, I'm having problems with attempting to flash the program... |
H: AC adapter: Input power vs Output power
When I look at, let's say an iPad AC adapter, the input/output rating on the charger states:
Input: 100-240V 0.45A (AC)
Output: 5.1V 2.1A (DC)
I know that the input and output ratings are maximum. The AC voltage in my country is 230V. Through a simple calculation, I can dedu... |
H: Light sensor to sense light level
I have an application where I am trying to monitor a defect in a web based manufacturing process.
This defect can be seen if one side of the substrate is lighted and the transmitted light is viewed from the other side. When the defect occurs a change in the transmitted light is no... |
H: how the CPU start by execution stored in motherboards flash memory chip
I had read that at start, the CPU program counter register is fill with F000.
I though that:
PC registers contain the next instruction address.
This address is send to the address bus and value return to the data bus
Does the address bus only... |
H: Arduino Uno Doesn't show up under Serial Ports, but it does show up in Device Manager
My Arduino Uno doesn't show up under Serial Ports in the Arduino IDE, but it does show up in Device Manager.
I have a I2C Sainsmart LCD connected to the Arduino.
Do you have any idea why it would do this?
AI: This happens from tim... |
H: Why set PORTx before TRISx?
I was browsing through the example code that MikroE provides for PIC programming using MikroC, and they always set PORTx before setting TRISx. What is the reason for this?
Since TRIS just selects whether the port or pin is output/input mode, why does it matter what the pin is set to befo... |
H: H-bridge vs ESC
I'm familiarizing myself lately with the usage of ESC (Electronic speed control).
I'm unable to determine when is it the best option to chose ESC over H-bridges? - in terms of advantages and disadvantages.
Why do -at least from what I've seen- people us ESC to drive and control brush-less DC motors ... |
H: Impedance problem (polar to rectangular)
Having a little problem understanding why this example converted polar to rectangular form to get Z. What is wrong with just leaving it in polar form and doing the algebra to get the value for Z
AI: It's semantics. If someone asked for an answer as impedance then I would ten... |
H: Does L293D consume power when not in use
I am designing a robot using the L293D motor driver, and I have just successfully hooked it up to my micro controller. I am using two batteries, one two control the motor and one to control the pic micro. I am wondering if the battery that is used to drive the motor would ... |
H: Measure peak voltage / amp, when signal is very short (relay on/off)?
I was measuring a 'steer' signal for switching on a relay. The oscilloscope, gave me back it peaks at around 2.64V. The width of the signal is 132ms.
I then hooked up my multimeter, to measure how much amp was drawn. However the reading varies (b... |
H: Why don't all motors burn up instantly?
A motor rated for 3S (11.1 V) has an internal resistance of 0.12 ohm. The maximum current is 22 A.
11.1 V / 0.12 ohm = 92.5 A
Doesn't this mean that by supplying a 11.1 V three phase current, the motor will burn up instantly? How does an electronic speed control (ESC) preven... |
H: Kirchhoff's Laws and Circuits?
I just started circuit analysis today and learn't about Kirchhoff's Laws.
Its pretty straightforward, but in all the examples my book gives they already specify the direction of the current and the end of the branch with the higher voltage.
For example,
there arrows everywhere indica... |
H: How to trigger something once a day
What would be the right thing to use if I want the base of a transistor to be high for 12 hours and low for 12 hours?
I ask because I would like to make a circuit that regulates temperature in a room. To do this I am using a ntc thermistor and a ptc thermistor that I have set to ... |
H: Pseudo-Nmos inverter in LTSPICE
In LTSPICE, I've built a pseudo-NMOS inverter and I've got 2 tasks to do using it.
1) I've a initial guess for Wn value of NMOS. I start the simulation with this value however, I need to optimize it and get a more precise value.
Basically, when Vol < x for some x, I need to find the ... |
H: why dc machines have double layer winding?
why do dc machines always have double layer winding?is it possible to create a single layered winding dc machine?
More generic Question: Can anyone explain the logical evolution of dc machine from the prototype (single coil) to the actual double layer-distributed winding c... |
H: What is wrong with this SPI implementation
I designed a system with RaspberryPi and STM32F407's, communicating with each other via SPI interfaces.
For the last 3 months, tests were OK but yesterday a RaspberryPi and 2 of STM32F407's SPI ports were burn out. I don't know why. Everything was working, I went to slee... |
H: Do the capacitors on the picture look broken?
I have here a CD player's board (the player is from 80s, Gründig CD 30), the player works OK first 10 seconds, after that there is loud noise (sound is still possible to recognize but is very very cracky). The capacitors [on the picture] look somehow strange to me, part... |
H: Enabling Pins on the Adafruit Motor Shield V2
I have soldered together an Adafruit Motor Shield (Version 2) following these instructions for standard headers (non-stacking headers). The end result looks similar to the image below:
I'm hooking the shield to an Arduino Uno and I want to hook up some sensors to thi... |
H: SN754410 output supply current - heating
I am experiencing excessive heating problem with SN754410NE (SN754410). I know that I can use heat sink, but I want to be sure that I am not doing something wrong.
I am using SN754410NE to drive a bipolar stepper motor. My circuit is similar to schematic below. The current r... |
H: Designing a bluetooth 4 low energy device - what needs to be taken into account for future FCC and CE certifications
We are designing a BT4LE device based on Nordic chipset with chip antenna.
The question is how can we understand is it required to put the chipset into an RF shield or not?
I've seen some BT4LE devic... |
H: What are the disadvantages of using FPGA dev kits as the 'final product'?
I understand that serious HW firms can manufacture their own boards, but what are the disadvantages of using a development board 'in production', i.e. placing a PCIe card into a server and performing calculations on it?
AI: The biggest one is... |
H: H-bridge - concern about mosfets
I want to create an H-bridge using MOSFETS (IRL620SPBF). I am trying to run a 6V motor which requires max current of 1.2A . The transistors Q111 and Q112 provide level conversion as the 'signal' comes from a Dev board at 3.3V. The DAC signal comes from the Dev board (0 - 3.3V). For ... |
H: Circuit design for variable number of leds
I am very new to this field and turned onto it by adruino and raspberry pi. So for my next project I am looking to create, I wanna have 6 leds (20mA 3v) in a line. Now depending on my output from raspberry I want a certain of the 6 to be on at time and not the others and s... |
H: Just making sure I won't fry my motherboard?
I'm building this circuit, which converts a toggle switch to a momentary one, which sends a key to a USB keyboard PCB by connecting 2 contacts together:
I just wanted to check, how do I know the keyboard PCB won't get fried when I flip the switch to 12v DC? Or worse my... |
H: Powercast Powerharvester Chipset PCC110 Issues
I recently picked up a PCC110 datasheet, an RF energy harvester. I assumed the 3 pins would correspond to GND, Antenna, and Vout (the datasheet does not specify).
I attempted all of the permutations for the pins in a relatively radio noisy location, but I was unable to... |
H: Nickel 500 and 200 ohms at 0 Celsius
I'm trying to find resistance table for Ni 500 and Ni 200. I found tables for Ni 1000, Ni 100, NiFe 604 and NiFe 507.7. But I wasn't able to find resistance to temperature table for Ni 500 and Ni 200. Could you please give me these tables? Or is it possible to convert Ni 1000 re... |
H: Configuring PIC16F877A PORTA as digital output port
I am trying to use PORTA of PIC16F877A as digital output port. But somehow it does not seems to be working.
I am using MPLAB X IDE MPASM to assemble the code. Below is the code I am using to initialize PORTA -
banksel PORTA;
clrf PORTA;
banksel ADCON1
movlw 0x0... |
H: cny70 with 40106 and PIC, only detects 1 time every time I reset
I am using a PIC18F2550, a CNY70 and a 40106. (Schematics below)
The problem is that when I turn on the circuit, the first time the CNY70 detects something works perfectly (I have 1 led in every B output, except for B0 that is the interrupt input). Th... |
H: Avoiding solder mask in certain region in Altium PCB design
I want to have a region in my PCB without solder mask while the other regions should have solder mask. I am not sure how do I do it in Altium? Is it by having a Solid (copper) Fill in the Top/Bottom Solder layer?
AI: The solder mask layer is a "negative", ... |
H: How to adjust output current on a buck converter?
I 'm planing to use a zinc–carbon 9 V battery to power up:
the circuit that battery belongs to
BeagleBoard-xM
I 'm thinking of using a breadboard, in order to power up both circuits. Beagleboard-xM's electrical specification is 5 V, >1.5 A. For this reason, I plan... |
H: What does "SoC bringup" mean?
Saw the term "expert in SoC bringup" on a job description for an embedded software developer: SoC here refers to System-on-Chip, but I was wondering what the term "SoC bringup" meant.
AI: "SoC bringup" generally refers to the process of porting an operating system to a new embedded sys... |
H: Reading to PIC32MX's memory in C and XORing big sets of data
I have a project in which I have 102 8-bit PISO shift-registers in daisy chain configuration and they are outputting to a common SDI line connected to a PIC32MX controller.
There is a total of 816 bits I need to read and store in the memory so I can manip... |
H: IC555 flyback driver troubleshooting
I made a flyback driver which just uses an astable 555 circuit to drive the flyback. The 4 and the 8 pins were connected to the positive rail. 7 pin was connected to the positive rail via a 1K resistor and a 10K pot. The 6 pin was connected to the 7 via another 1K resistor and p... |
H: Oscilloscope sweeps only once with DC sources and shows nothing on GND setting
I got an old CRT oscilloscope someone had laying around unused in his garage (an ATAIO AI 751A which seems pretty obscure, not getting any meaningful Google results). Unfortunately the user manual is missing, I couldn't find it online an... |
H: Can I replace a 2N222 by a BC558B, BC549C or BC327?
I just started studying Arduino and I'm watching a online course. I got into the stage where we're suppose to build some sort of protection system so we can plug-in outsourced power supply and prevent the arduino uno from frying.
My problem is that the class cours... |
H: Scaling down the sensitivity of an MEMS mic
I'm using an MEMS mic ADMP401, and the datasheet said, that the sensitivity form the chip is -46dbV, my question, how to can the scale it down, mean that I hear only really loud sounds?
AI: The sensitivity of -46dBV means that with an incident sound level of 94dB (SPL) at... |
H: 74HC86 XOR datasheet say Schmitt trigger "action" - is there anything special about it?
I current have a Schmitt trigger chip to clean up an output from one of my optical encoders and I am thinking about using an XOR gate to feed in both encoder outputs to double my encoder output frequency. (Its a quadrature encod... |
H: What means coil inductance (h) for relays?
I'm looking at the data-sheet for a Single Coil Latched Relay. In there, i see the Coil Inductance (ref. value)(H) for Armature ON and OFF column.
Specs:
Rated Voltage: 3 (VDC)
Rated Current: 67 (mA)
Coil Resistance: 45 Ohm
Armature ON: 0.09 (H)
Armature OFF: 0.06 (H)
Si... |
H: Use water as a conductor for a circuit powered by 1.5v battery
I've tried to create this quite simple circuit.
V1: 1.5 v (AA battery)
LAMP1: 1.5 v, 0.2 a (E10 incandescent light bulb)
"Salt water": 10 ml regular water + 1 g salt
When I connect the wires together, the lamp lights up. When I connect the wires to ... |
H: How I find the current and voltage in this matrix?
My book above uses nodal analysis to find the current and voltage across the resistors.
Now consider this alternate circuit:
Look at the branch that doesn't any components (the second straight line with no components). How would I find the current across it? I on... |
H: Powering the MCU (basic), is this circuit suitable?
Shown is a basic circuit diagram to power a MCU. I am using the recommended caps for the test circuit for the regulator.
Should I put a diode between the +ve terminal of the power source and the input of the LDO just to be safe?
Will this circuit be suitable to ... |
H: Input resistance of a transistor circuit
I have a question from the razavi's microelectronics book:
I'm puzzled because in the solution provided, the first line states that:
"We know that the input resistance Rin = R1||R2||\$r_π\$."
While I understand if I transform the circuit's base input into Thevenin equivale... |
H: Measure on/off pulse of relay (with reversed polarity) with a MCU?
Below I have the following (simplified) circuit:
What I want is to measure (monitor) every time the relay switches on and off. The pulse is around 3V and for 32ms.
The problem is that the voltage is reversed, to switch off the relay (single coil la... |
H: Multiplex based autoscale, question on simple circuit
I was looking for a clever way to automatically scale voltages from, say, 0-50V with a mux to an ADC (0-5V) without worry of damaging my inputs.
My thought a simple amplifier with selectable gains would work: Select the lowest gain ratio first (i.e. 0.1x), and t... |
H: Voltage level too low for MAX232
I'm trying to connect TI's MAX232 to my Arduino so that I can communicate with my PC. I have connected it exactly as the picture shows:
Tx/Rx are not connected because I just wanted to see if I can get proper V+/V- on pin 2 and 6. At Vcc=5V I'm reading 1.9V on both - pin 2 and pin ... |
H: How can circuits always be solved?
I've just started circuit analysis. All the examples, I've seen so far involve using using KCL/KVL or nodal analysis. They all consist of setting up a system of equations and solving them which gives you all the voltages and currents.
But systems of equations can have no solutions... |
H: Connecting DAQs in Parallel
I need to connect a DAQ to an existing system which uses a DAQ. The idea is to connect the DAQs in parallel so the existing system is not changed. It is likely that only one DAQ will be used at a time. The DAQs will be configured to output a 0-10V signal. I believe this will be fine, but... |
H: Why are resistance matrices always symmetric?
My book says when using nodal analysis to find the voltages and currents in resistive circuits, the resulting matrix (of the system of equations) is always symmetrical. Why?
The exact quote is:
The node equations for networks containing only resistors and independent c... |
H: What is the best connector for this RF 434MHz transmitter module?
I have a few of these cheap RF 434MHz transmitter modules (see image below, on the left) that I want to use with my PCBs, but I don't want to solder them directly to the boards. I'd like to attach them to the PCBs using a sort of female conector. I'v... |
H: Current and voltage sources?
simulate this circuit – Schematic created using CircuitLab
From what I understand, the magnitude and direction from an independent current source is constant. What would happen in the circuit above? If currents flow they way they're supposed to from the current source, KCL is violated... |
H: L293D heating quickly under 0.5 A (driving a DC motor using adafruit motor shield v1)
I am using Adafruit's Motor shield to drive a DC motor I got out from an RC car...
Powering the Arduino from USB. And powering the shield from a 12V / 1.5 A Power adapter (the shield is using an L293D)
I checked the datasheet of t... |
H: Full duplex shared frequency radio?
Normally shared frequency analogue1 radios (CB, aviation, etc.) can't receive when transmitting, because the signal being transmitted is much louder and will jam any signal from different transmitter.
Is it possible to somehow subtract the transmitted signal to be able to pick ou... |
H: How does a cube sat communicate with ground station with a 1w antenna
I heard that cubesat signals can be received with a hand held radio. Its confusing me that how a 1 metre antenna radiating 1watt energy can simply be received using hand held radios. I am designing a pico sat. I don't which antenna to be chosen t... |
H: Wireless "Arduino" sensors - what is at least needed on circuit?
When I finished my Master Unit for Home Control, I want to attach some Wireless sensors via 433MHz Protocol. (At least 2 ones, 1 for Measuring the outdoor Temperature/Humidity with an DHT22 and Lightlevel and 1 for checking if my mailbox lid opened)
... |
H: 2 transistors in solar charging circuit
I don't quite understand this circuit. Why are there 2 transistors? Wouldn't 1 transistor be enough? The blink LED triggers the first transistor every time it blinks. But, how I understand it, the first transistor only triggers the second transistor. Why are 2 transistors ne... |
H: MSP430 blinking led
I started using MSP430 Launchpad and as I was examining the code for blinking a led I found something odd. The code is this and is a ready example:
#include <msp430g2553.h>
unsigned int i = 0;
void main(void)
{
WDTCTL = WDTPW + WDTHOLD;
P1DIR |=... |
H: Determining correct requirements of Instrumentation Amp in measuring large current shunt
I'm trying to plan out a project of measuring large currents from my car battery through a shunt, and specifically I need help with the INA.
I bought this Deltec 250 amp shunt from eBay, that looks to be rated for 250A in short... |
H: H-bridge output filtering
I'm driving A4952 motor driver with about 25khz PWM signal, with a simple coil connected as a load between OUT1 and OUT2. VBB is variable, testing with 15V but changing it doesn't alter the results.
As long as it's running with the PWM signal, coil works fine, and the output signal from th... |
H: How do I wire up this relay?
I'm making this circuit:
I've bought an Omron G5LA-1 non-latching SPDT relay. It looks like this (from the datasheet):
I'm struggling to figure out how I wire this up though. I believe I need to ignore a pin, but I'm not sure which. I also don't know what gets wired to which pin.
I ha... |
H: Is the Delay in Strain Data Due to Capacitance?
I have designed a sensor board which gives a strain o/p based on wheatstone bridge principle(change in stress is measured through change in resistance).
But the starting value is not at zero level,it takes roughly 40 to 50 sec to stabilize (Please refer the attachment... |
H: Simulating SMPS with ideal switch in LTSpice?
Yes, this in a portion of a homework assignment (hence the idealized and slightly asinine problem statement). Aside from solving the circuit (which I have done), I am supposed to simulate the following circuit using LTSpice. The problem is that idealized switch in the... |
H: Bit-banging I2C question
When bit-banging I2C using 2 PIO lines do these lines still need to be pulled high? Obviously using a dedicated I2C bus the lines must be pulled high as the pins are open-drain outputs but PIO pins aren't open-drain.
AI: Yes, both lines need to be pulled high at all time.
Also, when bitbang... |
H: Closed circuit Wifi over coax?
If you connect an access point to (PCIe/USB) Wifi card over coax (i.e. no antennas) will it work?
If it would work, what would the maximum cable length be?
(This is just a thought experiment. I know fiber optic cable is better for long distance networking.)
AI: If you used RG-58 at a... |
H: Differential Drive for Heavy Robot
I'm asking here another question in relation to my previous one.
I would like to know how would one proceed when you want to control a heavy robot with differential wheel drive. When it comes to sending PWM values, I cannot control the robot, i.e, I cannot make the robot go into a... |
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