Questions tagged [specifications]

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16
votes
3answers
4k views

Why do digital scopes sample signals at a higher frequency than required by the sampling theorem?

In the quest for a not so expensive PC scope/logic analyzer, I have found a nice little device it looks very well done and I know it will do the job. However looking at the specifications, I ...
14
votes
1answer
1k views

Where is the official RS-232 specification? [closed]

Searching with Google returned only 3rd party documents (i.e. from chip vendors or university lectures). Is there a main document of such specification, similar to USB?
13
votes
4answers
2k views

How to search for a component?

Whenever I start a new project, one of the first things I must do is search for suitable components to see if the project is feasible. Most of my projects are desperately space constrained, so I don't ...
11
votes
3answers
7k views

Why would I use 2N3904 instead of 2N4401?

2N3904 and 2N4401 appear to be very comparable parts in all specs. 2N4401 has a higher current rating, but otherwise they look to be about the same in price and everything else. Obviously it's ...
10
votes
5answers
12k views

Why is power consumption sometimes given in mA and not in units of Watts?

Why is power consumption sometimes given in mA and not in units of Watts? For example, consider the following statement: "A USB device specifies its power consumption expressed in 2mA units in the ...
9
votes
1answer
3k views

What are the differences between optoisolator output styles?

Digikey lists optoisolators with several output types: Darlington Darlington with base Photo FET Photovoltaic Photovoltaic, linearized Transistor Transistor, with base What are the differences among ...
9
votes
1answer
1k views

Why does this microswitch datasheet specify a minimum load current? [duplicate]

The Omron VX series datasheet mentions on page 6 that "Using a model for ordinary loads to open or close the contact of a micro load circuit may result in faulty contact.", and shows that their micro ...
8
votes
2answers
19k views

What does A x B mean when referring to wire strand count?

Stranded wire is often specified using two numbers in the format A x B. For example, 16 AWG wire might come with a 19 x 29 strand count. What do the first and second numbers mean?
8
votes
2answers
752 views

Is it possible for an opamp to oscillate at a frequency greater than its GBP?

I was installing a tl3141 into a headphone amplifier circuit and it appears to break into ~250mVp-p oscillation at 8-10MHz on the lower half of the waveform when fed a 1kHz sine wave. Is that even ...
7
votes
1answer
4k views

Aside from cost, is there any disadvantage to using thicker wire than required?

Say I've calculated the minimum wire gauge necessary to give me an acceptable voltage drop over my length of cable run at the voltage and current my application will use. Are there any disadvantages ...
7
votes
2answers
10k views

Transformer labeled 120v-60hz-35va-12v - What exactly does it do?

I have a pool light whose bulb physically broke, but I've found a way to open the water-tight bulb enclosure to get at the actual bulb. I'm trying to either hunt down a replacement bulb (rather than ...
7
votes
1answer
464 views

Does a zero-recovery diode really have literally zero recovery time? If so, how?

Some diodes are advertised as "zero recovery". Is this true? Or is it marketing speak for "so fast you couldn't possibly care"? If it's true, what makes a zero-recovery diode fundamentally different ...
7
votes
1answer
1k views

Why are 5 mm LEDs always rated at 20mA?

OK, maybe not all of them, but by far most of the 5 mm LEDs I've ever handled are rated with I(max) = 20 mA and I've been using them for maybe over 15 years. Why is this? Is caused by the size of the ...
7
votes
1answer
189 views

Whence this difference in supply current?

When I need a MAX809 I prefer the OnSemi part over those from Maxim or NXP because the former has a much lower supply current. But I was looking at the NXP datasheet again recently, and I noticed that ...
6
votes
3answers
1k views

What effect does bit depth of an ADC have on noise floor, THD, or any other specification?

I was told recently that there is a direct relationship between bit depth of a measurement adc and minimum measurable noise floor, which in turn affects accuracy of THD measurements of DUT. I'm afraid ...
5
votes
2answers
389 views

Why is the Active/Real Power Rating So Low for This Relay?

I'm trying to select a relay for a IoT project that will control a water boiler. I took a look at the HF32F-G relay, but some of the specifications in the datasheet weren't making any sense to me. ...
5
votes
3answers
3k views

Is it possible to design an amplifier with a given gain from a random discrete JFET?

A few weeks ago, I played around with a discrete JFET bass preamp design I found online (http://www.albertkreuzer.com/preamp.htm). One thing I realized from analyzing the circuit, running simulations ...
5
votes
2answers
4k views

What does a parenthesized current rating on a switch mean?

I'm speccing out some switches for a project... is this some standard notation I've never seen before? Electrical Ratings: 12(4)A 250V AC What does the ...
5
votes
1answer
215 views

Understanding specs of PNP transistor for replacement

I want to replace an ON Semicondutor BC557 PNP transistor with a Multicomp BC557 PNP transistor. It is just for general switching of LEDs. But the specs look different although they are same mode. ...
5
votes
2answers
3k views

Hart protocol implementation

I would like to implement the HART protocol and am searching for specifications of the protocol. I found that the Hart Communication Foundation manages the protocol and on this page it says that ...
5
votes
2answers
1k views

Unknown motor, specifications interpretation and use

I got a motor on the picture. Does anyone know what it was used for? My main question is if is it feasible to use it as a barbecue motor or is it too strong? Can I connect it to one or three phases ...
4
votes
3answers
687 views

Why do they place a high current device in a low current package?

For instance, it is said that the practical current limit of the TO-220 device is 75A. But I frequently see MOSFET devices for which the specified maximum continuous drain current is above 75A. (...
4
votes
4answers
2k views

How must I read this MOSFET specification?

I'm looking at this datasheet, which has this graph on page 3: The FET has an \$R_{DS(on)}\$ of \$14 m\Omega\$; how can \$V_{DS}\$ be > 10 V at 100 A? Shouldn't that be 1.4 V? And if it was 10 V, ...
4
votes
2answers
641 views

Electrical specification for minimum bias current available from 3.5mm cellphone microphone input?

If I understand correctly modern microphones integrated with headphones with 4-contact 3.5mm jacks for use with cell phones are condenser microphones, and usually contain a small, integrated amplifier ...
4
votes
2answers
44 views

What does cell phone wall adapter specs mean? [closed]

On many (if not all) of my wall charger it says: INPUT: 100-240V / 0.5A OUTPUT: 5V / 2A So, according to my poor knowledge this would mean that the input power ...
3
votes
3answers
7k views

Trying to understand Peltier module specification

I baught this module The specifcation says: ...
3
votes
2answers
206 views

Why does a Category 5 rated jack have different solder tail positions than a traditional jack?

I am attempting to specify a replacement part for a modular jack used in an original design (I basically need something that will stick out farther than the original). However, the part I would like ...
3
votes
1answer
473 views

What is the usable area (for connectors) of a PCI Express card bracket?

I have a number of awkwardly shaped connectors that I need to cram into a single PCI Express slot metal bracket without any of them colliding with the host PC case's metalwork. The connectors are a ...
3
votes
2answers
2k views

What type of LED lights are needed for detecting retro-reflective markers for motion capture project?

I've a project in which I want to add 10-12 led lights around webcam's lens so that the camera can detect retro-reflective tape in it's viewing area. How this process works is something like this. I'...
2
votes
2answers
189 views

What specifications matter when comparing TVS ICs?

I have been wanting to update a design I have to include a USB to UART Bridge and while looking at the datasheet for the CP2102N saw what is in the image below. I have never worked with a TVS before ...
2
votes
2answers
565 views

Suggestions for DC/DC converters with digital control

I am under quite some time pressure and I need to put together a document about how several DC/DC converters (preferably buck) with digital control compare to each other. I am pretty clueless, I have ...
2
votes
1answer
2k views

Selecting a ceramic capacitor: Rule of thumb for required DC voltage rating

What is the rule of thumb for the DC voltage rating when selecting a ceramic capacitor (MLCC). Example: selecting a X7R decoupling capacitor, system voltage is 5V. Can I safely chose a capacitor with ...
2
votes
2answers
2k views

What is meant by VCES in a transistor electrical specification?

I am studying the STMicroelectronic BUL216 NPN power transistor. Electrical specification like VCES is given by the Specification Sheet BUL216 Datasheet. Also, the VCEO spec. Both spec has to do with ...
2
votes
2answers
331 views

Can I use an open-drain NXP 74LVC07A output as level translator for an 8V CMOS input?

I'm designing circuitry that uses an NXP 74HC4051 analog mux with a +8V supply. An MCU with 3.3V GPIOs needs to control the mux S0-S2 selection inputs. I am wondering whether an NXP 74LVC07A, powered ...
2
votes
1answer
2k views

High/Low level voltage specs for an IC

I'm trying to work out whether I can talk via SPI without level conversion between a PIC at 5V and an MCP3202 ADC at 4.096V (Vref and Vdd share a pin on the ADC). I looked at the data sheet for the ...
2
votes
5answers
162 views

Finding LED specs

I received from a friend a bunch of 1W/3W (??) LED. The thing is, I can't find any specs for them. For sure I have a method to test them and find Vf/If, but is that method any good? I need EE's advice....
2
votes
2answers
250 views

How many segments are permitted in CAT 6A cable run?

How many segments are permitted in an F/UTP CAT 6A cable run? Segment endpoints require peeling back the foil and untwisting the pairs, which I fear will affect data speeds. I heard that a cable run ...
2
votes
2answers
4k views

Finding required maximum current rating for a diode which will run in PWM mode

Consider a diode rectifier which will transfer a PWM signal. The duty cycle rate of this PWM signal is \$D\$ (\$0 \le D \le 1\$). The diode on state current is \$I_{ON}\$, and no current will be drawn ...
2
votes
1answer
1k views

Transformer frequency dependence

I have a transformer that I've taken out of scrap. I'm trying to discern it's electrical specifications. In my setup I have a function generator hooked up to the primary winding, and an oscilloscope ...
2
votes
1answer
562 views

ARM8/ARMv4 properties for qualitative comparison between RISC, CISC, and MISC processor designs

Question: I'm wondering if anyone knows roughly what kind of power consumption one can expect from an ARM processor having the ARM8 architecture (ARMv4 instruction set)? (Edited) Note: I'm not ...
2
votes
0answers
56 views

How to design a 3GHz antenna? [closed]

I would like to design a 3GHz high gain antenna. S11 has to be below -10dB and the gain to be above 9dBi - and I want to make it smaller than 8cm. What kind of antenna is better to satisfy the ...
2
votes
2answers
80 views

How can I tell if a cable is rated for use as motor leads with a variable frequency drive?

I understand that the switching edges generated by a VFD can cause corona breakdown of the insulation on the motor leads. Due to this, it is recommended that some cables be used for VFD motor leads, ...
2
votes
0answers
204 views

SATA compliance test

Is there anyone familiar with the SATA interface compliance? I'm curious about the testing method. For TX test, there are PHY/TSG/OOB test items. And, there are BIST-L and BIST-TSA mode defined in ...
1
vote
2answers
3k views

SPI specifications

I need to program (in Verilog) a peripheral driver connected to an FPGA through 4 standard SPI pins. I have been trying to find an authoritative source that clearly specifies the timing diagrams for ...
1
vote
2answers
773 views

Are there open free USB designs?

I want to learn USB and its hardware interface and start with a trivial design. I found some VHDL in github for the ISP1362 and I wonder if that is a good starting point. I have already used Quartus ...
1
vote
1answer
408 views

Exceeding the relay contact rating and connecting to Arduino

I have an Arduino. A suitable relay can be directly connected to an Arduino (with a flyback diode) if its coil is rated at 5 V and 40 mA maximum. However such relays have a limit on the ...
1
vote
2answers
218 views

SD card speed class specifies “minimum sequential write speed” but not the “maximum sequential write speed”, why?

A speed rating for any memory device is usually how fast it can work. However, the speed class of SD cards actually specifies the "minimum sequential write speed". Please see here for evidence under "...
1
vote
2answers
85 views

What does the term 'min' mean in AAA Rechargeable cell current capacity?

While checking the specification of rechargable AAA Ni-MH cells, the specification shows 2 parameters Voltage say 1.2v and Current Capacity say 630 mAh. However the current capacity is preceded by '...
1
vote
1answer
122 views

Why are properties of components often given at 1 kHz?

The title pretty much sums it up. Aside from DC, why are the properties of components often listed at 1 kHz? I keep hearing that it is a "standard", but why 1 kHz? This seems to be pretty common in ...
1
vote
2answers
149 views

What exactly makes ICs have different operating temperature maximums?

What exactly happens to an IC that is (for example) specified at maximum 85 degrees C? Also, being made from I assume similar materials, how is it possible for another chip to have a higher rating ...