# All Questions

62 views

### Reducing LED PWM Noise: Which is the best option?

Driving an LED with a microcontroller should be easy. But when looking into noise, things can get complex... As an instantaneous voltage indicator used in a variable power supply (which will be used ...
100 views

### How can I use a generic doorknob as a capacitive touch sensor?

I would like to use a generic doorknob that's installed in a typical wooden exterior door as a capacitive touch sensor. I have found various references for the circuit, but I have some questions about ...
23 views

### Power supply issues when using LiquidCrystal and WS2811

I have been attempting to run a 16x4 liquid crystal display with both an Arduino UNO and I have also used a MEGA.. I loose power to the screen (flickering, etc) when attempting to animate 29 WS2811 ...
50 views

### Choosing the correct brake resistor for DC motor

I have a DC motor running on 24VDC rated 150W (~6,25A), how do I calculate the correct brake resistance?
39 views

### Technology mapping

The function given is: g=ACFG + ADEG + DHJ + BCFI and i am asked to perform the reconverge theorem on this function which means taking all possible pairs of LUT that share the same input merge them ...
26 views

### Getting a signal from a sensor in Matlab

I have a sensor from thought technology (http://www.thoughttechnology.com/sensors.htm) I want to use measured data from the sensor in Matlab. But when I use a sample code to get my signal ...
30 views

### PING))) + Arduino + Servo [closed]

I’m trying to make what  I thought would be a relatively simple project involving:   4 X separate PING))) Parallax ultrasonic distance sensors connected to 1 X Arduino Uno with 4 X Servos as 4 X ...
70 views

### Using an RC snubber with a triac. Is this design safe? (simulation included)

I'm designing an ac switch for a washing machine motor. No speed control is intended, only a switch to turn the motor on for 10 seconds and off for 10 seconds. I'm using a MOC3063 zero-detecting triac ...
47 views

### Help with this Sinsusoidal steady state problem?

The question is to find the values of $v_1$ and $v_2$: I got the following matrix: \begin{bmatrix} 0.64 < 38.66^{\circ} & 0.4 < -90^{\circ}\\ 0.85 < 28.07^{\circ}& ...
47 views

### Powering several amplifiers with one power supply

I need to power 5 industrial amplifiers for a project but I am not sure I can use one power supply for all. Here is the amplifier model I will use: http://www.hbm.com.pl/pdf/a0114.pdf And manual says ...
122 views
+50

### Building a wireless keyboard (preferably with a kit)

This is the project that spawned these earlier questions. I'd like to create my own keyboard. Functionally it's going to be a keyboard, but visually it's going to bear more semblance to a joystick ...
109 views

### How do I amplify a dc voltage that is too weak to trigger the base in a transistor?

I'm trying to take the voltage output from a 3.5mm audio jack and have it light up an LED according to it's voltage. I was going to attach the left audio cable to the base of a 2222n transistor which ...
42 views

### XBEE S2 RPSMA not working with batteries

I have a couple of XBEE S2 with RPSMA antenna I'm using the xbee explorer(with arduino) and XBIB development board with X-CTU on a PC. if I drive the arduino from the USB,,, it works... not really ...
33 views

### Changing sheet size in Eagle

How can I change the sheet size in Eagle? I want to do this both for board schematics and the package design area. The latter is especially annoying. I'm inputting a BGA part and I can't zoom in and ...
43 views

### What type of stepper motor should I use in my project and how do I control them?

I'm building a video camera pan and tilt head. Here's what I'm getting at: I'll need one motor to control the horizontal rotation of the camera, and one for the vertical. The horizontal motor ...
22 views

### Building an Arduino Universal IR Receiver [duplicate]

I am trying to build a universal IR receiver on Arduino. I was thinking of using this external IC for demod+filtering of signal. http://www.datasheetcatalog.org/datasheets/208/301092_DS.pdf However, ...
128 views

### What's an alternate pin function on a microcontroller?

I'd like to know what "Alternative Function" refers to in the context of the IO ports of a microcontroller. I don't need to know how to activate it when connecting to a peripherial, but I'd like to ...
40 views

### Infra-Red with arduino [closed]

Good Day, I am trying to build a universal receiver transmitter with an arduino. Basically, I want to understand first how the IR protocol works on normal remotes. Is the signal transmitted modulated ...
107 views

### Are these pcb layouts good?

I'm working on an USB audio interface; the board has an analog section, with amplifiers and filters for the input and the output signals, a digital section, with the DAC, ADC, and the microcontroller ...
42 views

### Thermocouple signal conditioning - how to deal with low output swing margin of amplifier?

I have this thermocouple conditioning circuit. Let's say my gain is 100. Minimum low level for AD8237 is 20mV. As K type thermocouple outputs 40uV per 1C, I will have 4mV per 1 degree C. This ...
45 views

### Piano keys touching detection

I would like to make glove with pressure sensor on each finger to detect a moment when piano player touches a key. What kind of sensor should I use? I tried use simple buttons, but it is very ...
51 views

### Optimal Solution for function using Distributed Law [closed]

I was given the function: $h = 𝐴.𝐵' + 𝐶 + 𝐵.𝐶'.𝐷 + 𝐵.𝐸 + 𝐵'.𝐶.𝐷'.𝐹$ I was told to construct it in the most optimal way using only any size NOR gate by applying distributive law. I ...
290 views

### How did handheld video games from the 70's and 80's work?

I'm curious about how the early handheld video games from the 70's and 80's worked. You know, those small games with a LCD display with "fixed elements" meaning it was hard wired for one (or a small ...
76 views

### Is there a transistor comparison chart or database to be found?

When picking a transistor, I usually start with my supplier's catalogue and search and refine according to the specs I am most interested in. However, I seem to often come out with odd choices. For ...
31 views

### Are all 12 v dc batteries the same? [closed]

I have this pool skimmer that has 2 motors on a floating boat thats skims the top of the pool as it cleans. It uses a 12 v NiCad rechargeble pack. When it died I bought a 12V Lithium ion batter pack ...
55 views

### Designing stable PMOS voltage regulator

As a follow-on to the question "Using forward voltage drop of diodes with linear regulator" I am looking into designing PMOS voltage regulators. General Topology A common problem with the intuitive ...
87 views

### How to reduce a noise on a serial line

I have set up serial communication between my Arduino and a sensor stamp. The sensor stamp in question is Atlas Scientific EC stamp. The communication uses RT232 RS232 serial protocol. The replies ...
25 views

### Open source software for schematics [duplicate]

I am looking for an open source (or just free) software for creating electric schemes. It would be better if your program could do other schematics (for instance, installation schemes of physical ...
49 views

### Split any headphone with remote control and mic into Mic TRS+ Headphone TRS+USB

The main question is in the title. So I bought a headphone mic Y splitter yeasterday, and the right headphone output didn't work. I took it apart and tried to solder it to the headphone jack with no ...
46 views

### How to calculate battery capacity required for home applications?

The issue I'm facing is calculating current draw from different household items. Like, if a fan is rated at 75 Watts, its current draw would be A = W/V so A = 75/220 and A = .34 amperes. That doesn't ...
44 views

### Arduino Micro Clones? [closed]

I am using an Arduino Micro for a project I'm working on and I'm tempted to try out a clone. Has anyone had experience with using an off-brand board? My main question is regarding the IDE: are there ...
38 views

### What's the difference between delayed branch and branch prediction?

I'm studying how delayed branch works and I'm trying to distinguish delayed branch from branch prediction. What is the difference? Is delayed branch a means to facilitate a control hazard?
108 views

### Placement/routing of decoupling cap straddling oscillator guard ring on dsPIC

Changes in my design are forcing me to replace my 44-pin dsPIC33FFJ16MC304 with a 64-pin (same package size, finer pin pitch) dsPIC33FJ64MC506. In the datasheets for both chips, Microchip recommends a ...
39 views

### SEM Permanent Magnet DC Motor DPM 30R4 1500RPM 24VDC Output: 0-25kW & Brake

I am in the plannning stages of a project to build a pig rotiessiere. I have the above mentioned motor, but I am unsure of what type of power source is needed to run the motor and what can I do to ...
106 views

### How to build a voltage-controlled current sink / voltage-controlled resistor

I am trying to control a current through several current-mirror device (specifically the IREF pin on the TLC5940) using a single potentiometer. I've tried using a ...
95 views

### What does DAC resolution mean?

I am reading the specs of a DAC (this one), and it says the resolution is 10 bit. Does it mean it can generate 1024 voltage levels at the sample rate which is 12 GSa/s? It sounds pretty surreal. Can ...
27 views

### Logisim - Tunnel that outputs the OR result of all of its inputs

Consider this screenshot: When the two values differ, I get this: This makes sense, but it's a problem. I would like the tunnel to function like this: when it's getting mixed values, it outputs ...
74 views

### Control old printer motor with position ring

I purchased two old printers at a garage sale today in hopes of dismantling them and playing around with some stepper motors. After tearing both of them apart I discovered that there are no stepper ...
29 views

### Sample and Hold

When we have a data source oscillating at a frequency of say 4KHz , this implies that the Nyquist sampling rate would be at least ...
37 views

### Using ldr to power a circuit on night

I've been trying all night to use a 10k ldr to power on a circuit at night without sucess. It's a simple circuit that uses a MAX1555 to charge a lipo battery and at night it should turn on a led ...
34 views

### Adding the AVR Dragon's HVPP to the Arduino IDE

I would like to teach my Arduino IDE to use my AVR Dragon's HVPP (High Voltage Parallel Programming) interface to upload compiled sketches to my boards (an ATMega1284P-PU in this case, supported by ...
133 views

### Most efficient way to read analog signals in c++

I am new to AVR programming, and I am trying to learn the basic I/O with C++. I am trying to find the simplest, most efficient way to read analog signals using the same function for different ...
112 views

### Using noise to increase effective resolution of ADC

I managed to increase the effective resolution of a 10 bit ADC by several bits by repeatedly sampling a noisy input and taking an average over many samples. I'm wondering what some techniques are ...
28 views

### Msp430g2553 i2c communication library with itg3200 gyroscope

I've been creating an I2C library for communicating with ITG3200 gyroscope for MSP430g2553 experimental launchpad. I still have slight problems with sequential reading and the signed values but I'm ...
43 views

### How to plug 2 5m RGB LED light strips together?

I got two 5 meters RGB LED light strips and would like to connect them together, controlling them as a single strip. Each strip power is 72 W, the input voltage is 12V, it has 300 5050 SMD LED ...
130 views

### What do you use a board like this for?

I'll start by saying that I'm a software guy, I know literally nothing about electronics. I recently bought a raspberry pi, and while browsing at my local electronics shop, saw this board for \$5. ...
105 views

### Using forward voltage drop of diodes with linear regulator

I want to clamp the output of a adjustable three-terminal linear regulator Vout to -1.8V relative to a reference voltage Vref. My approach is to use the forward voltage drop of three diodes but I am ...
81 views

### Two questions, caps again

If I discharged my caps on thick bronze rails connected to the caps by copper wires and nothing else, would that be dangerous? I'd like to safely discharge the caps as fast as possible for the ...