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8
votes
2answers
8k views

How do I get an Arduino (5 V) and MPR121 (3.3 V) to talk?

I have the Sparkfun MPR121 I2C Capacitive touch sensor breakout board I have read that it uses 3.3 V, I know that I can't just connect up the 3.3 V power supply output from the Arduino as the ...
7
votes
2answers
7k views

Tips for wire-to-pad and wire-to-wire soldering?

After a simple flashy-LED kit's worth of practice, through-hole soldering is fairly straightforward. What I'm still having trouble with is wire-to-pad and wire-to-wire soldering. The first problem is ...
4
votes
3answers
1k views

Entry level books/magazines/software/websites for a beginner

A bit of background: I have a masters in engineering, mostly electronics. That was years ago however, and I've been working in finance since college. I've learned a great deal of programming as a part ...
85
votes
4answers
55k views

What kind of components are black blobs on a PCB?

In low-cost mass-produced items I often run into black blobs of what looks like resin applied directly on top of something on the PCB. What are these things exactly? I suspect this is some kind of ...
8
votes
3answers
4k views

Identifying Capacitors

I bought a mixed bag of ceramic capacitors from Maplin and I'm struggling to identify most of them. I'm a bit of an electronics newb, but I understood that a capacitor usually has 3 numbers on and ...
5
votes
2answers
2k views

How do you know which way round a 6-pin SOT23 goes?

Well, I have a 6-pin SOT23 and it is absolutely tiny. When I say tiny I mean it. Anyway, it is unclear which way it goes around as it has no indicator, so I don't know how I can install them on my ...
7
votes
6answers
737 views

Cheap way of temperature testing my boards

I want to make sure my product will work over a large temperature range of -40C to +75C. I can verify on the low end down to about -18C using a household freezer (which is probably good enough) but I'...
2
votes
3answers
769 views

Voltage rating and tantalum capacitors

I was originally considering using a 10 µF 6.3 V 0603 ceramic capacitor for stabilising the onboard voltage regulator on my microcontrollers. However, it may not be capable because of ...
1
vote
2answers
250 views

Can I use a Bakelite MES Globe Holder to convert a lantern into a table lamp?

I want to turn a Moroccan cast iron lantern into a table lamp. Could I use a Bakelite MES globe holder to wire in a light globe? Bakelight MES Globe Holder:
4
votes
3answers
1k views

Programmable system on chip (SOC) pluggable on a host via PCIe

Does anyone know a COM which is put on a PCIe card, which has some flash memory, some RAM, JTAG support (or some kind of debugging support), some input ports like USB, perhaps support some output like ...
6
votes
9answers
3k views

For UART, should I use parity on a board level?

I am considering whether to use parity or not with my UART. It is a board level high speed (upwards of 115,200 baud) signal. The traces are very short (less than 2 cm), MCU to DSP, but they could pick ...
4
votes
1answer
2k views

Suggestion for a GPS module with helical/omnidirectional antenna [closed]

I'm looking around for a decent GPS module for a project of mine. The Sparkfun GPS Buying Guide is nice, but focuses mostly on modules with patch antennae. My project is a wrist- or upper-arm-mounted ...
3
votes
2answers
4k views

Beyond board power, understanding multiple power supplies and loads in a circuit

I have a project I am looking to power where the secondary load is more than my Arduino can provide amp-wise. I need to know the simplest way to power the whole system. I will be powering the Arduino ...
4
votes
1answer
654 views

Can Resistance of wires be ignored?

I'm trying to calculate the internal resistance of my rechargeable batteries and haven't got a single battery holder so using I am having to using Banana plugs and Crocodile clips for holding my ...
1
vote
4answers
2k views

Arduino +squidbee GSM shield + ethernet shield

I am triying to make a webserver of the ethernet shield to send SMS messages via the squidbee GSM shield Apparently i can't connect both the GSM shield and Ethernet Shield to the Arduino... Is this ...
1
vote
1answer
4k views

Problem with PIC24F UART

The problem I am having is with my PIC24FJ64GA002 and the UART module(s). The 24F I have is in a SPDIP28 package and it is a new B5 chip (just one under the latest B8 revision) from Microchip Direct. ...
10
votes
2answers
789 views

Do batteries last longer with constant current draw or spiky current draw?

Do batteries last longer with constant current draw or spiky current draw? Or, as is implied by the accepted answer to "Making a battery last a long time in a microcontroller circuit", do some ...
2
votes
2answers
2k views

How to apply process corners in HSPICE?

How can I apply process corners (TT, SS, FF) to my simulation in HSPICE?
1
vote
1answer
4k views

Fixing a broken Metcal handpiece

I bought a Metcal STSS-PS2V-02 soldering iron from eBay, it was cheap and in need of repair. The previous owner had some problems with the handpiece and tried to fix it himself. I can't get it to ...
5
votes
4answers
5k views

arduino 3x3 LED matrix

i am trying to get a 3x3 matrix with multiplexing up and running. here is my setup: i have connected each rows cathodes and each columns anodes and connected that one to pins 0,1,2 resp. 8,9,10 the ...
5
votes
2answers
415 views

Buying RF metal shields [closed]

Where can I find those metal shield cans that you can solder directly on a pcb for EMI shielding? Just like the ones on the back of XBee modules? I'm not having any luck searching on farnell, perhaps ...
7
votes
7answers
1k views

Could induction thaw ice?

Last week we had very cold weather; and as a result there were lots of frosted pipes (iron and plastic). I spent a lot of time defrosting metal pipes with a torch, but could not do the same with ...
2
votes
3answers
708 views

My country's voltage is 220 and I want to recharge a Japanese cellphone (100V), what should I use?

I live in the Netherlands and can't recharge my Japanese cellphone because I think it's due to the difference in voltage. What should I use in order to recharge it anyways? Thanks!!
4
votes
3answers
882 views

How to approach designing a 30GHz bandpass filter?

How would one approach designing bandpass filters in the 3GHz - 30GHz range, each with ~2.4GHz bandwidth, for a 50Ω spectrum analyzer or sampling oscilloscope? I've learned how to implement some ...
6
votes
9answers
2k views

Getting started with a microprocessor

I'm reading about a microprocessors at the moment and wondering if I could get started with an 8-bit microprocessor. What would I need to get started. I understand that they need external RAM and ROM. ...
3
votes
1answer
227 views

PC Power supply for a PC/104. Current output

I have to do some work on a PC/104 CPU board. Until now I have been powering this from a separate power module (acs-5151 at the same link) that took in 8-40V and gave +12, +5, and +3.3 out. Until now, ...
3
votes
2answers
739 views

Are transient suppression diodes necessary for a battery powered system?

I've seen on designs where there is a TVS transient suppression diode on the voltage supply. For example, when the voltage supply is say a wall plug. However, are such diodes really necessary in a ...
16
votes
3answers
10k views

How to implement a soft power switch controllable by microcontroller?

I want to design a circuit such that the microcontroller can toggle a GPIO pin and shut the whole system (including microcontroller itself) down. And when the user presses a momentary button, the ...
10
votes
6answers
16k views

Small cheap electronic solenoid valve?

I want to make a device that can control a small solenoid valve for dispensing fluids. Basically a circuit which powers on and off the solenoid at different times to allow the fluid to flow. The ...
3
votes
1answer
1k views

Need circuit to close switch on detecting current (12V)

I have a project where I need to detect whether a 12V circuit is live or not. If it is I want to close a switch (actually close a digital IO input on an Adicon SECU16 Digital IO controller). I am ...
2
votes
2answers
473 views

Correct EL Driver Rating for 8 Channel Sequencer

I'm trying to use an 8 channel EL sequencer (found here) to control eight 10-foot segments of EL wire. I'm having trouble figuring out what the appropriate length rating is that I need on an inverter....
10
votes
1answer
5k views

Tips for identifying an unknown chip?

What tools and techniques can I use to identify an unknown IC with no markings? Today I encountered a microcontroller under an epoxy blob. The blob had 11 pads on each of four sides, perhaps 44tqfp. ...
1
vote
3answers
2k views

Where to find 478 motherboard circuit schematics?

I have searched for 478 motherboard circuit schematics on the internet, but have found none. Are any available publicly?
6
votes
2answers
6k views

How to work out resistance of milli-ohm resistors?

I have a dilemma. The schematics for a development board I am using specifies that it uses 20 milli-ohm resistors for current sensing (7 current sense channels). However, by calibration (using low ...
7
votes
4answers
723 views

What is the name of this common metal tubing?

I see tubing used all over the place in machines, but I do not know what it is called. The cross section looks somewhat like this drawn picture. Can someone clue me in on it?
1
vote
1answer
2k views

What are the electronics parts of a CD player

Can more experienced engineers give me their input on this. If I open a CD player, what electronic parts should I expect to find?
8
votes
9answers
807 views

Robotics Events

I'll be putting on a robotics competition in a month, and would love to see a list of different sorts of events I might be able to run. What are the types of competitions you are aware of, at all ...
1
vote
1answer
211 views

touch film replacing keyboard

I am evaluating whether it can use "resistive touch film" in project-based cards using USBizi Chipset-100 in place of a conventional keyboard. I would like to see some similar design to see howto make ...
2
votes
4answers
757 views

Determine the position of a ball joint by image processing

I am wondering if it is possible to sense the position of a ball joint using: A photodiode array from an optical mouse, embedded in the socket A specific pattern deposited onto the ball A processor ...
7
votes
4answers
905 views

Any good reference for digital architecture implementations of floating point arithmetic operations? [closed]

I am doing a thesis project. I need to make a FPGA implementation of a neural network. I want to implement some mathematical functions such as an exponential function. Does anyone know of any good ...
1
vote
1answer
2k views

ATtiny V-USB with 115200bps? DIP only

I know there are several solutions for V-USB using only DIP Parts (especially the ATtiny) like IgorPlug http://obdev.at/products/vusb/easylogger.html http://cesko.host.sk/IgorPlugUSB/IgorPlug-USB%20%...
1
vote
7answers
2k views

7 Segment Display - Hiding the electronics

I'm building a basic thermometer that displays the temperature on 4 seven segment LEDs. I want to put the circuit in a box with a clear plastic lid. I'll mount the LEDs on the PCB around the other ...
8
votes
3answers
6k views

Which microcontroller has good linux supported simulator?

I am looking for a good microcontroller to learn electronics. EDIT I want develop on linux, and I wish there is a good linux supported simulator. I want use C language.
2
votes
4answers
2k views

Compare negative with positive, ignoring sign

I need to compare a negative voltage with a positive one, each on the order of a few hundred millivolts each; I want to compare the magnitudes, ignoring the signs, although only for this particular ...
9
votes
2answers
712 views

avr microcontrollers and how to get started coding init or main loop or timers or interrupts

I have been modifying AVR and PIC microcontroller code for a few years now for work but have never written anything from scratch, I understand it pretty well. I am starting to write my own code now ...
6
votes
7answers
3k views

Multi-channel bar graph LED drivers

I want to build a circuit that shows the real-time frequency components of an audio signal on a number of bar graphs of some sort. Currently, my plan is to build 12 band-pass op-amp filters, and then ...
2
votes
3answers
2k views

Plans / tutorial for sound effect generator using only analog components?

I've been wanting to make a laser gun sound effect attachment for my son's bike. Currently, I'm using the electronics salvaged from his old laser gun toys. All of them seem to use electronics hidden ...
8
votes
7answers
6k views

Switching a Kettle On/Off using a arduino

First of I have no experience with electronics so I am not sure what I should be searching for to get this done. All I have with me at the moment is a arduino and a few connectors and LED's. Is it ...
3
votes
4answers
2k views

Does anyone have code to emulate a 16-bit input shift register with an ATtiny2313?

I would like to use an ATtiny2313 to emulate a Super Nintendo controller because I have an ATtiny2313 but I do not have an input shift register and I don't feel like soldering wires onto an existing ...
5
votes
3answers
616 views

Stepper motor substitution

I need to find a inexpensive replacement stepper motor and I am wondering if all of the specs need to be matched or are there some that don't need to be exact. Right now they are using a six wire ...

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