Most Popular
1500 questions
21
votes
3 answers
Getting started with PCB Layout for BGA Packages
Are there any good resources for learning the intricacies of PCB layout when dealing with BGA packages?
I'm very familiar with layout for almost every SMT part that has leads on the edge (QFP, TSSOP, QFN, etc...) However, I have not ever had a…
Connor Wolf
- 32,168
- 6
- 79
- 138
21
votes
4 answers
Supercap compared to a battery
What is the current state of things when it comes to super capacitors and batteries? Are super caps anywhere near rivalling LiPo's in capacity?
I've often heard people talking about super caps as being a viable replacement for batteries, in that you…
Thomas O
- 31,786
- 58
- 184
- 322
21
votes
2 answers
Microcontrollers/microprocessors and different bit versions, what's the difference?
As a general engineering hobbyist, I am learning more about the world of microcontrollers each and every day. Once thing I don't quite understand though is the significance of the bit version of a microcontroller.
I have been using the ATmega8 for…
capcom
- 5,902
- 14
- 48
- 59
21
votes
6 answers
Diodes in parallel or series
I am wondering what the effects are of putting diodes in parallel or putting them in series. (like current capabilities, voltage capabilities etc.) Let's say I have a datasheet of a diode. What characteristics would change ? My estimation is that…
skyler
- 10,196
- 28
- 81
- 132
21
votes
6 answers
Why would a circuit designer use parallel resistors?
I've been reviewing this reverse engineered schematic of a bmax6 style lipo charger.
To my understanding this circuit is used to dissipate excess charge in a cell when balance charging. The circuit uses a parallel resistor network as the current…
Mazaryk
- 337
- 2
- 5
21
votes
5 answers
Why do FPGA projects always take the same amount of time to compile?
With software, when we compile the project for first time it may take a while but afterwards, it does not take so long anymore. If we change a single file in the project, everything does not need to be compiled again.
This does not seem to hold true…
gyuunyuu
- 2,023
- 8
- 36
21
votes
6 answers
How does a fuse blow at its current rating, regardless of voltage?
I know from reading elsewhere that it's safe to use a fuse with a higher voltage rating when replacing one, so long as the current rating and reaction speed is the same.
For example, if a fuse is rated 125V 1A, then a 250V 1A can be used.
Let's say…
JYelton
- 34,119
- 33
- 145
- 265
21
votes
7 answers
Random number generators using a GPIO pin?
I just read through question AVR Random Number Generator and encountered a number of ways to generate random seeds in an AVR:
Use a special-purpose "Secure AVR"
Use an internal temperature sensor
Read unwritten EEPROM
Measure time intervals between…
Vorac
- 3,131
- 5
- 31
- 55
21
votes
5 answers
Why is the PCB part number traditionally on a copper layer?
I'm an experienced board designer, having designed 100+ boards over the past decade, and I have yet to hear a good answer for why the PCB part number is traditionally on an external copper layer, and the PCBA part number is on a silkscreen layer. To…
Fix It Until It's Broken
- 877
- 8
- 13
21
votes
9 answers
Does the "Avoid using floating-point" rule of thumb apply to a microcontroller with a floating point unit (FPU)?
As a rule of thumb, I try to avoid using floating-point in my embedded system codebase.
Floating-point variables are:
Computation-intensive
Not atomic (can cause problems in an RTOS application or with interrupts)
Their precision can cause…
gbt
- 691
- 6
- 17
21
votes
6 answers
I'm TV technician, but I don’t know how to save or protect the boards in my workshop
I have main boards, power supplies, and so on as spare parts. But sometimes they spend several years in my workshop waiting for a customer. When I find the right customer, several times the boards were damaged, mostly because of corrosion.
How could…
NIN
- 423
- 4
- 11
21
votes
7 answers
Is there any definitive I2C pin-out guidance out there? Not looking for a "STANDARD"
EDIT: This has been repeated several times, so putting it on top: Yes, it is well known that there is no "standard" for I2C inter-device connectors, but surely this community can formulate a list of "guidance" points for making such interconnects,…
Anindo Ghosh
- 50,446
- 8
- 105
- 201
21
votes
5 answers
How to communicate faster than the system clock
I was reading about the new (ish) Thunderbolt 3 today, and was very impressed by the specced speed of 40Gbps. Then I looked at Intel's latest i9 processor speed... about 4.2GHz max. How can a system communicate almost 10 times faster than the clock…
Isaac Middlemiss
- 668
- 6
- 22
21
votes
3 answers
How to secure cables to a PCB
What is a good way to secure cables to a PCB?
There are some good advice in the following post, but the application is slightly different:
Securing electrical cables to holes in enclosures?
In this case, the strain-relief/securing of the cables will…
K0ICHI
- 429
- 4
- 10
21
votes
2 answers
Why did they use ultrafast diodes in a 50 or 60 Hz bridge?
This is again from an HP power supply (PSU). The incoming 230 V is rectified into 340 VDC and is fed to a switched-mode supply. The odd thing here is that the manual for that unit, HP6023A, has different diodes for CR1, CR3, and CR2, CR4.
CR1 and…
AndersG
- 546
- 3
- 10