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1500 questions
22
votes
8 answers
Pre-programming surface mount ICs
I'm trying to set up a PCB with an atmega168 and no programming header. I intend to use a serial bootloader (there is a ft232 on the board) to reprogram but I am wondering about the best way to program the bootloader on. Has anyone else tried this…
jeremy
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22
votes
3 answers
Lithium Battery Protection Circuit - Why are there two MOSFETs in series, reversed?
I was studying a battery protection chip and reference circuit (below) commonly used in cell phone Li-ion batteries, and am confused by the two MOSFETs in series on the negative terminal EB-. According to this question , I now understand that…
Ryan Griggs
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22
votes
12 answers
Solutions for holding oscilloscope probes (and freeing up hands)
I have a problem, I only have two hands and the newer oscilloscopes come with four probes. This leaves me with zero hands to press the trigger button (even if I hold three probes with one hand I still can't use four). I usually have to ask a…
Voltage Spike
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22
votes
2 answers
Difference between a rectifier diode and signal diode
Can somebody please explain to me the differences between a signal diode and rectifier diode in terms of their electrical characteristics and their Lissajous patterns? I know that Shockley's equation is used as the mathematical model for the general…
D Brown
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22
votes
3 answers
Do MOSFETs usually burn open or closed?
I was wondering if a power MOSFET fails due to overheating, will it usually burn as an open-circuit or short-circuit? Also, does over-temp damage usually cause the gate oxide to blow through as a low resistance ( < 100 Ohms)?
Adam
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22
votes
11 answers
When is it okay to exceed the absolute maximum rating on a part?
I've always thought that the absolute maximum ratings on a part are the limits that thou shalt not violate. Period. End of story. However, another engineer is making the case that it's okay to exceed the absolute max rating for the input voltage on…
CHendrix
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22
votes
3 answers
Dual-SIM phone, do they use 2 GSM modules ? Anyone has high level schematic?
As an slight extension of my project, I am trying to see if I can improve connectivity resilence by using a dual-SIM approach. Dual-SIM phones (or Tri-SIM, quad-SIM phones) are quite popular in many developing countries, and AFAIK, most are based on…
bdutta74
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22
votes
7 answers
Identify processor type from raw binary code?
Not really related to chips, but hopefully I'll get some directions to follow from here. I got a chunk of code, but I don't know what processor it intended for. Are there tools available that can help me identify the code type? What statistic…
mentalist
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22
votes
8 answers
Why don't we have more registers in microprocessors?
Registers are theoretically not required; all microprocessors would still work without registers. But this seemingly trivial addition has helped make microprocessors more efficient. Why can't we have more registers to further extract benefit from…
Darshan Chaudhary
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22
votes
3 answers
Why does an inductor behave as a capacitor at high frequencies?
In truth, I've only been told this anecdotally by an instructor, but can someone explain the physics at play? I have been told that if an inductor is driven at a high enough frequency, it will begin to behave as an capacitor, but I cannot figure out…
Michael
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22
votes
5 answers
Can I use ST-Link programmer for non-ST chips?
Can I program all kinds of SWD-programmable chips (ARM-MCUs) with ST-Link?
Meylis Cherkezov
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22
votes
2 answers
Why do condors get electrocuted by power lines?
Plenty has been said about why birds are safe to land on power lines. But condors, apparently, are not . The linked article explains that condors are electrocuted often enough and endangered enough that they are doing special "power pole aversion…
Nate Glenn
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22
votes
4 answers
Why did my fuse blow after 3+ years of no problems?
For several years, I've had a solenoid wired to the 24VDC output of a PLC (Rockewell Automation 1769-OB16 ). To protect the PLC output card, a fast-acting 500mA fuse was installed between the PLC and the solenoid. The fuse has been working without…
user86927
22
votes
8 answers
STM32 & ST-LINK - Cannot connect to MCU after successful programming
I have built my own board with STM32F7-45VGT6. I have successfully programmed it with ST-LINK v2 (not the original one though) and now I cannot even connect with MCU. I use ST-Link Utility from ST and SWD interface. It can be the case that I use SWD…
zupazt3
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22
votes
5 answers
Whats does "hr" mean among "V" and "Ah" in batteries?
I have a battery which indicates 12V25Ah/10hr. What does 10hr mean here? I guess "hr" stands for "hour". But 25Ah already means if battery is fully charged and if I load 12V 25A (=300W) to it, it should last for an hour (correct me if I am wrong).…
Farrukh
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