Things derped engineers say.

[joblessalex]

In this post, I want to hear all the stupid things either you, or a friend has said about electronics. Bonus points if you can confuse the higher engineers!

I'll start.
"it's a current limiting power supply, the circuit can't blow up!"

[brabus]

OK, so...

A: This circuit needs 12V, 1A supply.
B: nice! I can give you this 12V 3A spare supply!
A:  are you mad? 3A would fry it!
B: 

[c4757p]

"it's a current limiting power supply, the circuit can't blow up!"

That's a good one. How about "It's not the voltage that kills you, it's the current"? Can't say I've heard an actual engineer ever utter that one, but a perhaps a friend...

[Recyclojunk64]

"It's not the voltage that kills you, it's the current"

Yeah, one of my friends has used that statement many times in conjunction with

100 Amps?!?! [lead acid car battery] that'll blow your arm off!!!

[Rufus]

"it's a current limiting power supply, the circuit can't blow up!"

That's a good one. How about "It's not the voltage that kills you, it's the current"? Can't say I've heard an actual engineer ever utter that one, but a perhaps a friend...

''volts that jolts and mills that kills'' which is quite true.

[c4757p]

It is "true", yes, but only useful under the consideration of Ohm's law. Most of the dopes who like to recite it have no idea why a 12V 300A supply will not kill you and a 120V 300mA one will. It is both true and reckless.

[olsenn]

Ohm's Law is not a law, it is a definition. The real law is P=V*I. Since either of these terms being zero would give zero power, if you have non-zero (real) power, you also have non-zero voltage and current. Dividing any two non-zero numbers will result in another non-zero number, and so we define R as that number (V/I).

Back when the only electronics/circuitry was metal wires and light bulbs (no AC, semiconductors, etc) I'm sure scientists believed that voltage truly was always proportional to current (in other words it's a law) but after discovering this not to be true we just never gave up the theory because it would mean admitting we were wrong all these years... it's easier to say it is a law but has exceptions... even though laws have no exceptions.

[c4757p]

Absolutely correct. I guess that just like I'd say "it's not the volts" is technically true but useless, I'd say considering Ohm's law there is technically false but useful. I'm really more referring to the general idea that current increases when voltage increases, regardless of the actual mathematical relationship. It's silly to say that volts don't kill, since volts make amps possible.

Way too many people confuse the current that will flow through their body with the current that will flow through a metal bar. That 12V 300A supply is not 300A when you touch it, and something only having a lower current rating does not in any way make it safer.

[c4757p]

100 Amps?!?! [lead acid car battery] that'll blow your arm off!!!

For what it's worth, a car battery is incredibly dangerous. I'd rather accidentally shock myself than accidentally bridge a car battery with a wrench.

[dr_p]

Me: how much cocoa does that chocolate have?


Colleague (with EE degree): why does that matter?


M:well, more cocoa is generally healthier.


C:why?


M:for starters there's less of the other stuff (sugar, colorants, flavors etc) and cocoa in itself is good for you, it's got fibers and helps some other stuff, I don't remember exactly. Ball park figure 50% cocoa is decent.


C:GTFO, even the chocolate that's 75% cocoa contains all the nasty stuff


M:yes, but less


C:no, they have the same amount, be sure.


M:they can't have more than 25% of the other stuff, because 75% is already cocoa. Dooooh


C:you are implying 75% cocoa means three quarters of the chocolate is cocoa ) that's insane, it's too much powder


M:well, what do you thing "ingredients:cocoa(75%), ..." means?


C:that the cocoa used was not pure, it was 75% pure.


M:and how much of the "impure" cocoa did they use?


C:I don't know..


M:I do.....

[Psi]

An engineer/lecturer at uni once told us that 'teletext' transmits your page request from your house TV aerial and the TV studio responds with the requested page.   

He even drew a nice diagram on the whiteboard showing the communication.

The few of us in the room who knew just how wrong he was were all in shock and just let him continue.

[c4757p]

The few of us in the room who knew just how wrong he was were all in shock and just let him continue.

Yep. Can't say I haven't done that.

[Psi]

Speaking of chocolate percentages.

You should try 99% chocolate sometime, It's crazy strong.

Almost impossible to chew without being overcome with bitterness. You have to let it dissolve on your tongue.

http://www.lindt.com/swf/eng/products/excellence/excellence-99/

[c4757p]

You should try 99% chocolate sometime, It's crazy strong.

Ew! I don't even like regular "dark" chocolate - candy should be sweet! If I want bitterness I'll drink coffee... 

[nuhamind2]

My friend ask this in class
F: Can common emitter amp be used to amplifiy electric power?
Other friend in another class
F:What if we couple a generator to motor and power the motor from generator?
L:Power will be dissipated on the wire resistance

[Excavatoree]

"That device doesn't need large wires because it draws a lot of current, the wires are large to reduce the voltage drop."

[c4757p]

F: Can common emitter amp be used to amplifiy electric power?

As much as it shocks me every time I hear that, that's a common misunderstanding of amplifiers. I guess these people can't be bothered to think back to physics.

F:What if we couple a generator to motor and power the motor from generator?
L:Power will be dissipated on the wire resistance

Well... technically true...

[Skimask]

"Hey, Watch this shit!"

[Balaur]

Speaking of chocolate percentages.

You should try 99% chocolate sometime, It's crazy strong.

</Chocolate freak/snob mode on>

Eh, all this commercial stuff is rubbish (I've tasted a lot actually)

Best black chocolate is made from Criollo beans. A 75% bar is sweet and almost chocolate-milk-like. A 100% bar is an acquired taste, but I definitely enjoyed very much (I'm actually in the same area as one of the last French chocolatiers who manufactures chocolate from the raw bean by himself).

I do prefer milk chocolate though and my "go to" chocolate is the standard "alpine" Milka. Very good quality/price ratio.

</Chocolate freak/snob mode off> Sorry 

[c4757p]

"Hey, Watch this shit!"

 

[peter.mitchell]

"Hey, Watch this shit!"

That is in the same league as
"How hard could it be?"
and
"What could possibly go wrong?"

[ecat]

It must be a software problem.

 

[ddavidebor]

You MUST drive led by voltage.

[c4757p]

You MUST drive led by voltage.

I'm not even really sure what this means.

[c4757p]

It must be a software problem.

 

Q: How many programmers does it take to change a light bulb?
A: None, that's a hardware problem.