# All Questions

12 views

### Wireless communication under water

I am looking for a under water wireless communication, distance up to 3000 meters. For this I quickly did some research on it and found out that Acoustic communication would be the best solution since ...
14 views

### Debouncing a TTL Photodiode Detector

I am designing a photodiode sensor that will sit on a computer monitor and will output a +5V TTL signal if the screen is displaying and image and a 0V signal if the screen is not. The prototype ...
14 views

### What's wrong with my solar charger? [on hold]

I have one of those solar USB chargers. The spec says it can output 4.5W at 6V. I plugged my Galaxy Tab4 8.0 onto the USB port. The tablet says "Not charging". Based on information I found on the ...
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### Electronic Speed Controller - Brushless DC - Quadcopter

Im a student who'd doing electrical and electronics engineering. Im currently doing my final project which is a quadcopter. One of my objectives in that is to make a Electronic Speed Controller (ESC) ...
18 views

### Any good color sensor for lane detection?

Long story short, I'm working on a project that allows sensors to detect if a car is driving off lane. I want to measure how often the driver makes small adjustments to see if he/she is driving with ...
50 views

### Poorman's shunt theory

Background I'm doing a DIY project of bulding a 1kW Induction heater. in the process I have built a poormans PSU out of a MOT ( and a 50V 25A brigde rectifier. with not even nearly enough of a ...
29 views

### Using a LS248 7-segment driver, but segments are dim. Can't figure out why

I'm building a project where I want to use two double-digit 7-segment-LED displays (green, common cathode). From what I've read, a shift register wouldn't be able to source enough current, so I ...
24 views

### 6Mbaud UART with Bus Pirate V4

I would like to sniff data on an SPI bus running at a clock rate of 6 MHz. I would like to use the Bus Pirate V4 for this task. The sniffing itself is supported up to 10 MHz, the problem is getting ...
36 views

### Which bus is it necessary to use and where can I find it?

I'm trying to make a tiny navigation system with 6 IMU sensors. The main requirment is accuracy and distance between sensor and master. Now in prototype I use I2C, but the length of wire connecting ...
15 views

### Noise Source in Direct Form 2 Diagram

I'm having a Direct Form 2 Diagram created from a signal The task I'm trying to solve tells to assume that every multiplication != 1 and != -1 gives sigma² amount of noise. We should mark the ...
24 views

### Implement Multiplexer

How can I design the following MUX from the circuit in the image?
111 views

### “Hot-knife”/Thermal cutter power supply design

Im undertaking a DIY rope cutter project to avoid paying for the ~\$150 storebought ones. Many resources online told me to use a light dimmer + transformer configuration and i had planned to go a step ...
51 views

### Make an opamp go rail-to-rail on a voltage higher than opamp supply

So I've chosen to work with an High Frequency Opamp that can only use 5V for power (I can't use any other Opamp). But I need the signals to go Rail-to-rail at say, 24V. So naturally I thought I'd just ...
14 views

### AT+CIPSEND problem with ESP8266

Here I am facing an issue with ESP8266 CLIENT Programming. The Problem is with AT+CIPSEND Command. This command is working for few times, but after few cycles, it waits too long for "SEND OK". I have ...
172 views

### ATmega328 very deep sleep and listen to serial? [migrated]

I have investigated the sleeps options of the ATmega328 , and read a few articles about it , and i would like to understand if there are more options . So i would like to get as low current as ...
40 views

I'm preparing for a test and I currently stuck with the following question. We have a 6502 microprocessor. For the execution of an absolute jump the jump address with the address high byte (ADH) and ...
74 views

### What does a router do?

This question in its current state may be too broad, so I'll clarify. Obviously, most routers today are a combination modem, WiFi transceiver and router, taking the signal off the phone line, ...
11 views

### Static electricity motion sensor

Is it possible to make an efficient motion sensor using only transistors?I tried this with a couple of NPN and PNP transistors and then with a MOFSET .When someone walked by , a LED would turn on , ...
63 views

### Transistors emitter pin has lowered output [on hold]

I have a BD135 NPN and BD136 PNP transistor, When i try to apply 5V of power to the collector pin, The emitter pin Voltage output is much lower. The goal i want to achieve for this circuit is to ...
43 views

### Single MOSFET Amplifiers

Why is it that when I see single MOSFET amplifiers or even complementary ones (one NMOS and PMOS), they would use what in single BJT amplifiers would be called "Common Emitter Amplifier". The output ...
22 views

### Manually triggering a low active pin

I have a microcontroller with an active low reset pin. This pin is connected to a timer that periodically triggers a low edge and resets the microcontroller. What would be the best circuit that would ...
30 views

### storing data on internet server

the concept is that...iam measuring wear measurement of xyz...sorry i cannot reveal the name..basic concept is that ..i have interfaced barebone uno with RF 434Mhz modules...so until there is no ...
19 views

### Where can the detailed requirements for CE marking (Low Voltage Directive compliance) be found?

I'm designing an appliance that probably has to comply with the European Low Voltage Directive. I've been searching for a guide on how to design a product complying with this directive, but I haven't ...
19 views

### Autoelectrics: Testing components off 12v battery

I'm quite good with mechanics and am just starting to learn more about electrics specifically applicable to automotive. One thing I am still yet to get the grasp of is the way electricity behaves. It ...
101 views

### Why do electronics components have maximum voltage and not just maximum current?

I am trying to figure out how electricity works and I wonder why do electronics components have the maximum voltage limit? Why does the voltage matter? Isn't it the current that can 'kill' the ...
35 views

### negative powers 8051

I am attempting to create a calculator using Keil C51 compiling for a DS89c450 target device, but I have run into an obstacle with regards to negative powers. The compiler keeps returning errors when ...
29 views

### Pir motion sensor

I have hc pir motion sensor when it sence a near person it output is 3.3v and I have 5volt relay and this output not work on relay .when I directly apply 3.3volt on relay then relay work or complete ...
50 views

### Earphones voltages?

How much voltage is required for the earphones by which we listen voice and songs ? Please help with the calculations if possible??If we keep our earphones plugged with our mobile phones,do the ...
39 views

### Where to Conect 3.5mm jack

I'm planning to build a speaker system (there is also a mic) within an alarm clock and would like have audio in/out functionality. For output, is it correct that i would assume the external speakers ...
31 views

### How would you dampen this little quadcopter?

Well, I made a little quad from scratch. From scratch as in from PCB design. After assembling, testing, some coding, it turns out my accelerometers get WAY TOO MUCH vibrations and I can't detect ...
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### How to utilize the flexible memory controller (FMC) in the STM32F746xx to interface with an LCD and SDRAM?

After reading one too many datasheets and whitepapers, I believe I have confused myself. First, though, let me explain what I want to do. I have a STM32F746BG (ARM Cortex-M7: Datasheet), and I need ...
67 views

### Preparing Signal for Sampling

I want to sample a voltage signal from mains. I found the following circuit but im not sure how it works. The circuit consists of precision amplifier and a buffer which I can't make sense of, the rest ...
595 views

### How to see electronically if a cup is empty or not

My requirement is just to know when a cup/mug is empty. I searched for weight sensors but they are bulky and expensive for this simple task. Is there any cheap solution for this task? Using weight ...
31 views

### Timer Interrupt for Case Statement

I have 3 states for a motion control system in a case: Accelerate, Steady, Decelerate. We start in the the accelerate case and when certain conditions are met, we move to the next state, etc. How can ...
11 views

### wireless charger coil/buck converter issues

I have a wireless charging receiver coil (output 5.6 v, 1 amp) connected to a variable buck converter. When I connect the wires, I get no output reading from the buck converter and the voltage on the ...
34 views

### SMD diode value

I need to change surface-mount diode but i need to know its value. possible your assistance to know the value of the diode in the picture. what is the value of diode in picture? or how to get the ...
27 views

### Given the dynamic and static power consumption how does one determine the total power for the capacitive load?

I get that the capacitive load is determined which is also indicated by this question: $$\frac{Power}{Voltage^2 \times frequency} = Capacitive Load$$ However, I am not sure how power (which is ...
105 views

### What is this type of radio fm antenna connector called?

I'm looking for an antenna replacement for my dad's busted radio (iHome IH8) and I'm having some trouble finding the name of this type of plug. The only things I find when searching online are coaxial ...
35 views

### Capacitor discharging problem

I have simulated the circuit in pspice...it is giving good result....but when v2 is low then both transistors are working so output capacitor should not discharge...here..it ...
78 views

### 8 bit MCU with 12 bit ADC, possible?

I am trying to measure battery's voltage and current but with a very high accuracy. So i've selected a 12 bit ADC to be interfaced (via I2C) with my micro-controller. My micro-controller will receive ...
33 views

### What is the required bandwidth for QAM modulation?

Why is the allocated bandwith smaller with QAM-16 or 64 compared to e.g. QAM-4? I am not a professional so I'm looking for an intuitive explanation.
28 views

### Finding Audio Output on a BeagleBone Black

I need to find a way to measure the start of audio output on a BeagleBone Black Rev C. Audio on a BBB: The BBB does not contain a DAC. The only supported audio output is through HDMI. Measuring ...
26 views

### Use a li-ion battery at two different voltages

I scavenged a li-ion battery from a broken laptop. It is made of 6 Samsung ICR18650 cells (3.75V 2800mAh), parallels two by two so that the total pack is in fact the sum of 3 cells at 3.75V, so 11.25V ...
30 views

### Calling a routine every x miliseconds

I'm working on a motion controller using the mbed platform. The idea is to calculate the theoretical position in the move every x milliseconds and then compare it to the actual position from the ...
30 views

### How could I read a digital input (an open/closed switch) from a smartphone without a digitizing board?

I have to read a single digital input signal (a trivial open/closed-circuit push button) and use this signal in an Android application on a smartphone. Of course, I could connect a tiny Arduino-like ...
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### Calculating Data rate function of bandwidth and SNR

I plotted BER vs SNR for BPSK modulation in Matlab and I am given bandwidth of channel (bandlimited channel). lets say it is BW1. I would like to find the data rate based on this information. I am ...
86 views

### Difference between logical and virtual addresses

Today I heard that a: DMA-controller is mapping/converting logical addresses (from I/O-Mapping) to physical addresses MMU-controller is mapping/converting virtual addresses to physical addresses ...
56 views

### Why are batteries measured in electrical charge unit (ampere-hour) and not in energy unit?

I've searched for an answer for this question for a long time. Specifically I've found this thread which is closely related to my own question: Why are batteries measured in ampere-hours but ...