The component-selection tag has no wiki summary.
0
votes
1answer
35 views
Source for a 6-pin DIL “stackable” header (for Arduino ICSP header)?
Does anyone know of a source for a "stackable" 6-pin DIL header? I would like to use one on an Arduino shield I am designing, in order to carry the ICSP header from the Arduino up through the shield ...
1
vote
2answers
102 views
USB device with a serial number and 3 LEDs
I'm looking for a way to build a USB key. I have a bit of experience with the Arduino, however for this project that seems to be a bit of overkill.
The key should contain a unique serial number ...
42
votes
4answers
2k views
What is the reason that the value “47” is so popular in electrical engineering?
We often see component values of 4.7K Ohm, 470uF, or 0.47uH. For example, digikey has millions of 4.7uF ceramic capacitors, and not a single 4.8uF or 4.6uF and only 1 listed for 4.5uF (specialty ...
1
vote
1answer
73 views
Help identifying/selecting SMD MOSFET
I am repairing an IP camera that has a blown transistor in the power supply section. The transistor looks like a SOT23 transistor, but it has 6 pins (how is that package called, anyway?), 4 of them ...
-1
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0answers
52 views
Amplifier for 40kHz ultrasound signal [closed]
I need a simple amplifier for a 40kHz ultrasound signal. I found this (source):
How do I calculate the values of the components?
0
votes
1answer
204 views
What there was before Arduino? [closed]
I'm really a fun of Arduino project, it's easy and it has a great community. But i am aware that is has no technological innovation, it is only a wrapper on a (normal?) microchip, if i have understand ...
0
votes
1answer
61 views
Help finding Buck/Boost Regulator IC
I have been trying to find a suitable Buck/Boost IC with certain features, but having gone through multiple Manufacturer's product tables, I can't find one that meets my needs. I think this is more ...
21
votes
1answer
435 views
Darlingtons, MOSFETS, and bipolar junctions
I realize there are dozens upon dozens of kinds of transistors, each used for specific purposes. Sometimes there is great overlap; multiple kinds may work in a given circuit, but at times only a ...
-5
votes
1answer
118 views
Information required in building DIY HHO production device [closed]
I am going to try producing HHO (creating hydrogen and oxygen) and have been told that a "100 Amp 12 volt pulsed wave modulator" will increase the HHO production. I believe they mean pulse width ...
4
votes
2answers
187 views
For switching 220VAC, is a specific coil voltage and coil resistance better than another?
Is there any reason why I might choose an EM-relay rated at coil-voltage of 24V or 12V, over one rated at coil-voltage of 5V, all other specs like contact max. current, switching voltage, life etc ...
1
vote
3answers
139 views
Choosing an MCU in a time-effective way [closed]
I'm spending a lot time figuring out which microcontroller I should choose for my projects.
For example, for one project I have the following requirements, in order of importance:
I2S interface ...
2
votes
4answers
276 views
Infrared spotlight project, need x50 resistors. How many ohms what type to use?
Infrared spotlight project.
I have a PCB BOARD set up for 150x 5mm IR LED
1.5-1.6 forward voltage.
Forward current is 60 mA
150 LED’s are divided into 50 groups (3 LEDs each + 1 resistor)
What ...
5
votes
1answer
189 views
Using the VO2223A to switch a 230Vac LED lamp
I'm looking for something that can switch on and off a 230 Vac, 26mA LED lamp, under microcontroller control. Would a VO2223A, driven by (say) a PIC or Arduino, work as a low-current SSR? The load ...
1
vote
2answers
193 views
How to select a proper transistor?
I've got a schematic that calls for an unspecified "NPN Negistor". From my understanding of the circuit, the NPN is an oscillator that generates two audio tones for testing. Here's the schematic:
...
0
votes
0answers
106 views
Sound level meter for a given range of frequencies
I would like to measure the quantity of noise. For example, I have found this sensor: http://www.phidgets.com/docs/1133_User_Guide
...
7
votes
2answers
205 views
How do you work out ripple current for a Power supply design
I hear the ripple current rating of a cap is important because caps have internal resistence which can cause over heating of capacitors. I was wondering is there any general rules a professional ...
1
vote
2answers
312 views
How much voltage/amperage can a NPN transistor take?
I got the MakerShed Ultimate Microcontroller Pack and it came with a "Transistor NPN". I want to use it (or probably buy something else) as an electronically controlled switch so that on arduino I set ...
1
vote
2answers
154 views
Flush/slotted actuated rotary switch knob?
I'm thinking of using the R10015RS02Q SP10T rotary switch for an upcoming project I'm working on.
It's marketed as having a flush/slotted type actuator which I think requires something like a ...
3
votes
1answer
252 views
What kind of knob fits a slotted potentiometer shaft?
What I thought was an easy question is more elusive than I suspected. I have a number of potentiometers that have smooth (not knurled) shafts with a slot cut into the end...it looks like a flathead ...
2
votes
2answers
297 views
Ideal analog switch to replace BNT / MOSFET in the modern world
When tackling with the very common need of toggling a current with an output from a microcontroller or similar chip, solutions have varied over time.
The oldest solution is to just use a BNT ...
4
votes
2answers
309 views
What's the difference between linear and audio tapers, and why should I care?
I'm stocking up on a variety of potentiometers to keep on hand for my audio projects, and I'm trying to figure out what to buy.
The projects I'm working on seen to call for either linear & audio ...
2
votes
1answer
175 views
rotary switch / turn knob? how to call it?
Im looking for a switch-like rotary knob, that i can turn left and right. Its outputs a simple 'pulse'. You find these in selecting/setting numbers on assorted electronics. You can keep turning them ...
4
votes
3answers
392 views
How to choose a inductor for a buck regulator circuit?
I am designing a buck-regulator circuit, with possibly the MAX16974 as the regulator. I have never done such a thing before, and actually not too much analog electronics at all. I got stuck at the ...
8
votes
3answers
331 views
A decent library of component simulation, schematic and PCB layout?
I am truly a novice in PCB design, so I am new to all aspects of it. What I am having the most trouble with is actually picking suitable components. The trouble I am having is that I am not really ...
3
votes
2answers
1k views
Selecting the right bridge rectifier
There are a number of schematics I'm trying to interpret that have bridge rectifiers. In the components list, however, they're simply listed as "D1-D4 rectifier unit" without any specific values.
How ...
4
votes
2answers
140 views
grounding connection?
What's the easiest way to connect a ring terminal to the ground terminal of an AC outlet? Are there plugs you can buy that make this easy?
I don't need (or want) the line and neutral wires ...
