EEVblog #304 - Mailbag - Page 1
Forum section: electronics / general

author: tnt
author_rank: Regular Contributor
timestamp: July 04, 2012, 11:44:35 pm
content: Hi Dave,Glad you like the pulse generatorA few comments :I put the design files are available herehttp://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

author: krivx
author_rank: Frequent Contributor
timestamp: July 04, 2012, 11:56:01 pm
content: Do you have any rise-time measurements for this build? Or should I wait for Dave's video?

author: EEVblog
author_rank: Unknown
timestamp: July 05, 2012, 01:16:02 am
content: Quote from: krivx on July 04, 2012, 11:56:01 pmVideo 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 jobDave.

author: dda
author_rank: Contributor
timestamp: July 05, 2012, 01:22:04 am
content: I was worried about the long thin package after you had opened the first.

author: T4P
author_rank: Super Contributor
timestamp: July 05, 2012, 02:24:28 am
content: That time when i got my digital calliper ( the same one you recieved )it came okay ... somebody must be having a bad day

author: PeteInTexas
author_rank: Frequent Contributor
timestamp: July 05, 2012, 05:30:11 am
content: Quote from: dda on July 05, 2012, 01:22:04 amYeah me too. I was imagining the "bodgy" electronics it may have had.

author: free_electron
author_rank: Super Contributor
timestamp: July 05, 2012, 06:05:31 am
content: i just watched the mailbag thing. hilarious. ladies wear...you can change the motto to :'Don't get turned on ... take it off'now

author: David_AVD
author_rank: Super Contributor
timestamp: July 05, 2012, 06:27:04 am
content: Quote from: PeteInTexas on July 05, 2012, 05:30:11 amSo the construction may have been somewhat "dicky" eh? LOL

author: peter.mitchell
author_rank: Super Contributor
timestamp: July 05, 2012, 07:42:22 am
content: 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.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: July 05, 2012, 10:30:24 am
content: That meter... Plug it into the wall in ohms mode. You know you want to.

author: Unknown
author_rank: Unknown
timestamp: July 05, 2012, 03:17:33 pm
content: Hi, some info which might be of some use to someone regarding digital caliper bus signals.http://www.shumatech.com/support/chinese_scales.htmRegards

author: Pat Pending
author_rank: Regular Contributor
timestamp: July 05, 2012, 04:03:19 pm
content: So much bubble wrap and still a smashed LCD glass ??

author: Monkeh
author_rank: Super Contributor
timestamp: July 05, 2012, 06:27:12 pm
content: Quote from: Pat Pending on July 05, 2012, 04:03:19 pmThere wasn't any seperation of items inside the bubble wrap.

author: LaurenceW
author_rank: Frequent Contributor
timestamp: July 05, 2012, 07:18:49 pm
content: 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.