@Asmyldof Working on finalizing my PCB today and tomorrow anyway.

@ThePhoton Are you being smart with the PCB?

:-)

I'm hungry

but it's also 2:30

might want to cancel my 8AM meeting

Or not

@Asmyldof Apparently not. I found one place where I didn't put a pull-up on an open-drain interrupt line. And two places where I put pull-ups on the same I2C lines.

@ThePhoton there's rules and filters that can help you avoid that

that's what I meant with smart :-)

@Asmyldof Is there a rule that will let you put a low-ohm series resistor in front of a digital output and then not gripe that the net on the other side of the resistor doesn't have an output pin connected to it?

If you have a rule set to gripe about signals not being hard driven that can only be fixed with a special resistor

I think

There's no "transparency component specifier"

@ThePhoton I think I may have though of a way, but I need to fiddle to see if I'm even remotely right

yay, support is really fast, a new keyboard in just a month, people should be praised for their speed...

@PlasmaHH Best start requesting a 2017 calendar

@Asmyldof more like requesting a new job...

nodoby heard me so far though

You're doing it wrong

like most of the things

I'm hungry

Still haven't eating anything since last I said that

now you might be doing something wrong here

like most things?

note entirely unlikely

Guess I'll have lunch then

when whacking together some simple oscilloscope myself, and it displays a square wave just fine after calibration, are there any likely caveats I can run into concerning its frequency response?

Band stop, band pass, tone-specific oscillation, more complex forms of frequency dependent attenuation or amplification

How is it possible to have a current flow through a dipole antenna if both ends of it are just open?

@trilolil magic

@W5VO getting this type of answers is why I like SE...

now a serious answer?

@trilolil when I went to college, there was a semester-long class that addressed this

@W5VO I am a last year university student in ee. But I am just a little confused about this.

what did you learn in your electromagnetics class?

@ThePhoton I tried (messing around in Altium looks like you're working to many people), but can't get it to work properly for all cases without making modified resistors.

@W5VO My current thoughts: Applying a sine wave to the antenna, causes the polarity of the antenna to change every time, as we use a voltage source (not a current source). This sine wave is not current only voltage. This changing polarity generates an emmanating EM wave. But I don't see where the current "comes in"...

@W5VO I know that current generates magnetic fields. So there s that...

@trilolil The trick is that an antenna is big enough relative to your frequency of operation that you can't treat it like a "simple" wire that you would find in a traditional schematic.

@trilolil Sounds like you need to take an electromagnetics class

@W5VO isn't it the other way around? The antenna is $\frac{\lambda}{2}$, i.e. a half wavelength. So smaller than the wavelengths themselves.

@W5VO OK I think I more or less see now. As each half of the antenna is a quarter of a wavelength this means you are at the peaks of your sine wave. Which corresponds with the omnidirectional radiation pattern...

@trilolil 1/10 to 1/20 of a wavelength is about where you can start ignoring transmission line effects as probably insignificant

@W5VO Do you mean reflections and impedance matching by transmission line effects? I don't see why you say that. How does this answer to my question: How is currentflow possible in an open circuit?

@trilolil self capacitance,. Kind of

@PlasmaHH I don't see how that relates.

Oh the joy of physics: the wife took a glass out of the dishwasher. It exploded in her hands, now tiny glass shards all over the place

@trilolil you need to bring the whole antenna to the same potential as the connected signal, electrical field wise. Thus you have to move electrons around

thx

@Asmyldof You mean make a resistor symbol with one pin designated as an input and the other pin an output?

@ThePhoton That's the only way I got it working fully with all kinds of strict driven signal rules

anyone got any thoughts on where to start if i want to create a 0V to 20V square wave with <20ns rise times?

@TheNoonMoose DIY or spending money?

hmm, either will do.

i'd prefer to buy something, bosses would probably like me to build it.

And how much power/ current?

i just need to drive an old CMOS input

so, presumably very low

trying to do propagation delay on a 15V part

Regular bjt inverter should do it

With some calculations to be sure about the rise time

It's easier if you aren't trying to keep power consumption down

@TheNoonMoose This is what I was going to recommend at first:

avtechpulse.com

But they're more for if you need a 1 A pulse or somethign.

i had been looking at something like this: berkeleynucleonics.com/model-505

not too different from your av tech stuff

@TheNoonMoose As long as you can bill your customer to cover the cost...

hahaha, hahahahaha

we're doing burn-in testing on these parts

yeah, we don't have a burn in oven yet

bosses decided they wanted the visibility of the order

so we'd just buy everything we needed to do it

fools

and they'd have their 28 year old first job "lead engineer" work out all the technical issues with such

hahahaha

at least i get to leave at 5 today

so, yeah, thanks for the help

@TheNoonMoose OK, I think you'll be able to hide a $10k function generator in that project. A new burn in oven is likely to involve knocking down walls, adding new power circuits, ....

ventilation ducts...