EEVblog #304 - Mailbag

[tnt]

Hi Dave,

Glad you like the pulse generator A few comments :

I put the design files are available here http://people.osmocom.org/tnt/hw/pulse_gen/ , the only mod is the addition of the CC-BY-SA license on PCB.

I didn't put a battery holder directly there because I wanted to mount everything in a tube and the the battery would fit "inline" with the PCB.

Concerning the connector yes, the other type would have been useful for scope testing but it's not easy to find good ones and I had a good BNC female / BNC female adaptor handy ... Also if you want to use it to test cables (Time Domain Reflectometry), it's not an issue if you have the right kind of BNC tee.

The appnote explain what you can tweak, there is also two through holes to connect a long coax (hard line) if you want to have the pulse last longer. Since my scope was only 350 MHz, I couldn't really see what difference several transistors made ... if you have better scope you might be able to compare to locally source transistors ...

PS: Hey, I've seen in the youtube comments some fellow "Louvaniste" (people from Louvain La Neuve where I live) and even from FSA / EPL as well it seems (school of applied sciences at the UCL university I attended).

PPS: btw: "Munaut" is pronounced "Mun" as in "MUNich"  and "aut" as in "HOse" (at least that's the closest match I can think of at 1am

[krivx]

Do you have any rise-time measurements for this build? Or should I wait for Dave's video?

[EEVblog]

Do you have any rise-time measurements for this build? Or should I wait for Dave's video?

Video uploading now. Although of course my scope is only 500MHz, so can't give a true value.
I tried to find a local scope somewhere to do it, but was out of luck.
Agilent have said they'll loan me a $100K scope which should do the job 

Dave.

[dda]

I was worried about the long thin package after you had opened the first.

[T4P]

That time when i got my digital calliper ( the same one you recieved )
it came okay ... somebody must be having a bad day

[PeteInTexas]

I was worried about the long thin package after you had opened the first.

Yeah me too.  I was imagining the "bodgy" electronics it may have had.

[free_electron]

i just watched the mailbag thing. hilarious. ladies wear...
you can change the motto to  :

'Don't get turned on ... take it off'

now 

[David_AVD]

I was worried about the long thin package after you had opened the first.

Yeah me too.  I was imagining the "bodgy" electronics it may have had.

So the construction may have been somewhat "dicky" eh?  LOL

[peter.mitchell]

hmmm...

now to start shipping random electronics from china to dave, just to see if they're useful to him.

EDIT: ordered some small boards, see how they perform for size and simplicity, im sure you could find something useful to use with them.

EDIT 2: forgot to change my shipping address back so i guess you can check out how dodgy the protection circuit is on a cheap chinese phone battery maybe even its rated capacity.

[nitro2k01]

That meter... Plug it into the wall in ohms mode. You know you want to.

[jucole]

Hi,  some info which might be of some use to someone regarding digital caliper bus signals.
http://www.shumatech.com/support/chinese_scales.htm

Regards

[Pat Pending]

So much bubble wrap and still a smashed LCD glass ??

[Monkeh]

So much bubble wrap and still a smashed LCD glass ??

There wasn't any seperation of items inside the bubble wrap.

[LaurenceW]

Dave, looking at the impedances around the avalanche transistor - pretty high. When you touch the transistor (collector) with your paw, you are providing a low impedance to ground (BNC shell), so THAT's why the oscillations die, I reckon.