EEVblog #866 - Mailbag

[Mephitus]

If people want i can order him something even more dangerous.

Check out bigclive.com or https://www.youtube.com/user/bigclivedotcom
 

He regularly does videos on some extremely sketchy chinese ebay tat. Like a 5 port USB charger that had it's grounding sheath tied into the 220v mains. Or a "water heater" that just uses open contact plates straight from the mains to heat the water.

[MatthewMorgan]

If people want i can order him something even more dangerous.

Check out bigclive.com or https://www.youtube.com/user/bigclivedotcom
 

He regularly does videos on some extremely sketchy chinese ebay tat. Like a 5 port USB charger that had it's grounding sheath tied into the 220v mains. Or a "water heater" that just uses open contact plates straight from the mains to heat the water.

Dave's reactions are comedy tho?

[Hypernova]

Just in case anybody is looking for the ebay listing..

http://www.ebay.com/usr/aberco

Postage to the rest of the world...... Ouch!

did order 2 though, and will frame them if they arrive intact.

Reason for the detector saturating is internal opamp saturating, as the massive signal exceeds the common mode voltage of the amplifier, either on chip next to the photodiode, or the one outside doing current measuring. A possible solution is to install an optical switch ( though at the cost of the sensitivity going down a lot) to blank the optical path during laser firing. You can use a second detector as well so you get the rest of the data, and this lower sensitivity data from the dead period should still be usable.

https://en.wikipedia.org/wiki/Electro-optic_modulator

The original use depends on the start of the pulse, and is specified for that. Saturation is not a worry on the typical system as they use a very good optical path to reduce leakage light. They want the first return pulse, and not the rest.

Bought the 20pcs pack, what good is disposable income if you don't use it, I spend more on the IEEE subscription I hardly use anyway.

[MatthewMorgan]

If people want i can order him something even more dangerous.

Check out bigclive.com or https://www.youtube.com/user/bigclivedotcom
 

He regularly does videos on some extremely sketchy chinese ebay tat. Like a 5 port USB charger that had it's grounding sheath tied into the 220v mains. Or a "water heater" that just uses open contact plates straight from the mains to heat the water.

And i also am already subscribed to bigclive,

Anyway emailed him and he already has this item.

[jesuscf]

If you want to play bullshit bingo visit http://www.bullshitbingo.net/cards/bullshit/ to get your card.

[strangersound]

If people want i can order him something even more dangerous.

Please do, that shit is hilarious! 

[kcozens]

Is this a slice of Dave's Brain?
Find out in today's Mailbag

At 41:32 you show a geocaching item. I've never been geocaching but I know someone who has done it in the past. I wanted to find out a bit more about geocaching so I joined the main(?) geocachine website. I found that the tracking item in your video has been logged by several people as having been last seen on your workbench.   I have also discovered there are about 50 geocaches within about 3.2km (2 miles) of my home. I didn't realize how popular this hobby is in my area. I have plenty of caches for me to track down if I want to get involved. At least it would give me something to do on my other than going over the same old routes I tend to travel during my walks.

[Halcyon]

Dave, what's the go with mobile reception in your lab? I noticed in this video you were on WiFi and your mobile reception was very low? I know the Sony Z3C isn't a crap phone (in terms of reception quality), so what gives? Either you aren't with Telstra or there is some very serious concrete going on and no pico-cells in your building?

[solarstandard]

Amazing mailag episode! Thanks, Dave! I really liked the wafer production steps and the Single Photon Counter. I wish there would be someone like Dave doing optoelectronics (lasers, photon detectors, electro- and acoustooptics etc.)... I find these things very interesting (and happend to be doing a PhD in). Maybe there is, anyone have any recommendations?

Or maybe Dave could do it? <: He seems very modest in saying he's not an expert, but he's doing it very well!

Here's a few ideas on regarding the Photon Counter and the signal in the first 2 us:

1) The signal is some sort of real optical backscattering, 2 us is only 300 m roundtrip for light, maybe there's something reflecting it back. Although the abrupt end of the saturaton makes this explanation unlikely.

2) Trigger-to-laser emission jitter? You say there's a 600 ns delay between the trigger rising edge and the laser emission and you show a long persistence trace. Is it the same pulse-to-pulse? Maybe 600 ns is just the minimum delay and it varies in the range of 2 us. I'm assuming your laser is Q-switched and these can have pretty much random trigger-to-emission delay. I believe it gets worse with increasing pulse energy.

3) EMI from the laser Q-switch ring-down? (Again assuming your laser is Q-switched). I've had major interference problems with a table-top mJ-level Nd:YAG Q-switched system and my detection electronics. After the laser emission the detectors would pick up us transients which would get worse the closer they were to the laser head and the Q-swtich PSU. Even some meters away I would get unacceptble EMI. And it's all with shielded BNC cables, grounded cases etc. It did get better with double-shielded cables though and erm... some tin foil wrapping here and there. Maybe it's the Q-switch EMI pickup that is triggering your detector?

4) Finally, if the detector has a gate input, why not use a fast PIN diode with a TTL pulse shaper and use the laser pulse itslef to gate out the initial detector response? (You may need to get creative to have the gate pulse arrive before the laser pulse). If the problem persists, you'll know it has nothing to do with the laser pulse and most likely is purely electronic.

And yes, the output for these detectors should be loaded with 50 Ohms. <:

[tszaboo]

I have half a dozen of these Foxanon (E14 6-ish W) running at home and they are not that bad. They use IC for current regulation, no blinking, the color temperature is sweet and they run more than a year no issues. Definitely not a Philips, but not Wung Hang Lo.

[Smokey]

Got my wafers today.  They look bad ass!  What do you guys think would be the best way to keep them centered in a picture frame so I can hang them on the wall?

[ccs46]

I was the one who ordered that horrible soldering iron.

It cost me £0.99 (AUD$1.86)

I think it might be one of the worst items he has every seen.

Was that 0.99p delivered??

If people want i can order him something even more dangerous.

Please Do. 

[Mephitus]

Got my wafers today.  They look bad ass!  What do you guys think would be the best way to keep them centered in a picture frame so I can hang them on the wall?

If I was completely bat-shit insane, I might just use some LOCA glue and put it between 2 panes of good optical glass in a suspended frame. But you would need to be careful as hell about bubbles. (LOCA = liquid optically clear adhesive)

[Smokey]

Got my wafers today.  They look bad ass!  What do you guys think would be the best way to keep them centered in a picture frame so I can hang them on the wall?

I ended up using some double stick tape in a circle around the outside of the wafer on the white mat that came with the frames and sticking the wafers to the mat.  Then the mat pushes them against the glass when you put the back on so I don't think they are going anywhere.  I'm super happy with how it turned out.

[Carl_Smith]

I have also discovered there are about 50 geocaches within about 3.2km (2 miles) of my home. I didn't realize how popular this hobby is in my area. I have plenty of caches for me to track down if I want to get involved. At least it would give me something to do on my other than going over the same old routes I tend to travel during my walks.

I was into Geocaching for a while but totally quit about 12 years ago.  I just recovered my account on the site about a week ago, and found there are around 700 caches within 10 miles of where I live.   But it turns out that a vast majority are "micro caches" that are just a tiny vial with a paper inside to sign, stuck with a magnet to a sign post or street light post.

I don't really get the point of those.  Years ago I did the geocaching to find interesting places to see.  I found more parks, hiking trails, interesting things like old bridges over creeks on old country roads in the middle of nowhere, than I had any clue existed in my area.  It was more about the journey and the interesting destination than actually finding the cache.   Walking 300 feet down the street and finding a paper in a vial on a sign post is not an interesting journey or an interesting destination.  Just another check mark on the geocaching site.  Guess I need to figure out how to do a search for "real" geocaches.

On another note, I've been thinking about how to repurpose an Amazon Dash button to be a "I was here" button for a Geocache.  I would need to be near an available WiFi AP though.   Maybe I should check if that's been done already...

[Nerull]

bigclive also got one of those irons, at least the wires on Dave's were attached:

[MatthewMorgan]

I was the one who ordered that horrible soldering iron.

It cost me £0.99 (AUD$1.86)

I think it might be one of the worst items he has every seen.

Was that 0.99p delivered??

If people want i can order him something even more dangerous.

Please Do. 

Yes it was £0.99 delivered.

[EvilGeniusSkis]

Why does the tencor wafer have a daughter board on it? Why not just build the brains into the wafer?

And "wet baby alert"? I thought that was a standard app in all Neuro-electronics projects.