ebay "0R - 9999999R Seven Decade Programmable Resistor Board, Step 1R, 1/4W" review

To satisfy my need for a decade resistor box I was looking for something cheep and I came upon this project. The idea was nice and simple, exactly what I was looking for but the price was not so attractive, 19$ + shipping for a little PCB with resistors and jumpers is way to much.

Next step was a little search on ebay and in no time I found the Chinese equivalent of the same idea at around 10$ and free shipping, now we're talking. You can find it on amazon also but the price is considerably higher. Fast forward a few weeks and the package was waiting for me at the post office.

And the ratings state:
- 7 decades coverage with 1ohm, 10, 100, 1k, 10k, 100k, 1M stages
- 1% resistors tolerance. Planning to replace resistors if the need comes with 0.1% tolerance
- 1/4W power ratting
- 250V max voltage, like that would be the case..

It came bulletproof packed. First time I've seen such a great packing, overkill in this case but a nice touch none the less. The PCB work was nice and clean, came with the male 4mm banana plugs and a bunch of extra jumpers. Banana plugs are the cheap ones but good enough and the extra jumpers beats me what they are for because I don't find a use in connecting more resistors in parallel.

With this occasion I had the opportunity to put my newly acquired DER DE-5000 to work. Got it with TL-21 and TL-22 accessories as the TL-23 is overkill for most cases and easy to home make anyway. Plugged the TL-21 alligator adapter, did an open/short calibration and clipped it on the Decade resistor board's jacks with all jumpers set to 0. Total disappointment! 0.8ohms!! That's almost 1ohm, not quite what I had in mind in terms of 0 resistance.
 

Couldn't find any problems other than, of course, the jumpers. Fiddling with them turned out values from 0.5ohms all the way up to 4ohms which is quite a tragedy. Took a closer look at the jumpers and couldn't find an actual fault with them. The mechanical contact is quite good, there was no sign of oxidation.. that's just the way it is, nothing to do about it.

So what did I end up with? The cheapest programmable resistor with 6 actually useful decades. Not the kind of equipment you can calibrate stuff with but good enough in situations where you need to test and tweak stuff.

YongNuo YN-622C review

Well, this won't actually be a review because you can already find that here, and I highly recommend reading that first. I just thought coming up with some extras.

So, first things first, ordering and packaging. Of course you can find them from big suppliers like amazon but I got a pair from the official ebay store, payed 94$. I ordered them on 23 November 2012 and even though they appeared as shipped the very same day I received them on 15 January 2013. Almost lost hope for them but can't put any blame on the sellers, holidays were in between and a lot of bureaucracy.  Got a pleasant surprise right at the post office though, as the package was marked as a gift and priced for 30$, great for dealing with customs.

Packaging is quite remarkable. First, there's the bubble wrapped envelope. Inside is an "original" fancy cardboard box, inside it a blank one with just a "tips" label on it (read the manual, don't use the units on a high voltage flash, it's OK to torn off the protective film), then comes two individual bubble wrapped bags protecting the tranceivers and an user manual and even a quick start guide. Even more, when I opened the battery cover I found a silica gel bag used to protect from moisture. The mentioned protective films protect the focus assist lamp and the top surface of every unit. I admit, I'm very impressed with the level of care these guys put into such a cheap product and yet so feature rich.

Unfortunately the so called documentation is quite hard to read as english is definitely not an often spoken language at Yongnuo, an extra reason to read that link I was talking about in the beginning. But that's hardly a problem with the amount of online support these days. The real problem I found was the fact that the hot shoe connection to the camera is not properly aligned as both units were having a slight left twist when mounted. It's nothing major, it doesn't even affect the focus assist lamp's aiming, but it's there non the less, for reasons that I can't understand. I thought about opening up a transceiver to get a look at the insides but is seemed it needed more than just unscrewing the obvious 4 screws, and that "more" I could not find. That also killed my hope that the misalignment can be somehow fixed.

The focus assist lamp is implemented through a laser diffraction grating that gets the job done in most cases. The limitation comes from a narrow central spread of the pattern and that fact that at close focus distances that pattern doesn't even cover the center focus point but stays above it because of the lens/transceiver parallel axes. That's not quite a big issue as it can be fixed if using single spot focus moved somewhere inside the assist projection pattern.

When it comes to weight, one empty transceiver is 76g, adding a pair of enloop 2400mAh got the scale at 136g. The enloops are quite an overkill for the task and regular batteries of cheaper rechargeables will do just fine and cut the weight a little. A nice surprise came from the battery compartment. Instead of the classical design where a spring is mounted at each end, here the springs rest inside the unit and metal pads at the insert/extract side. This makes the use much quicker and easier even though adds for a little attention to look at the battery marking.

But all this aside, what about using them? Well.. it can be as transparent as using a normal optically remote Canon flash or as complicated as other radio TX/RX offers with little buttons, lights and combinations. Point is.. it does it all, or the most of it at least. Am I happy with the purchase? Actually I'm waiting to get some money for another pair so I can use 2 off camera flashes.

Mini Dynamo Hand Crank USB Emergency Charger review

OK, I admit it, I was geek enough to order one of these gizmos from ebay. It was only 1$ so no harm done, right? Well.. rolled myself laughing when I saw the same thing for 20$ (twice reduced, from 49.99 and then 25) on amazon here. Luckily there's also another version here  for only 3.59$ :)) There are things about economy I just can't figure out.

But back to our little toy, if you haven't figure it out yet, let me explain it to you. It's a small crank driven dynamo that generates just enough juice to power an USB charging device like a cell phone, mp3 player or any other small type electronic, don't dream about tablets or other power hungry beasts. The key phrase there was "just enough" because it won't get to 100% but a charge or even a discharge to 10% and that's because the voltage out of this thing at "nominal" speed is lower than the standard 5V used on USB ports.











I knew from the start that it's a good for nothing toy but I couldn't help getting it and the first thing I did after unpacking was opening it up.

 It's pretty amazing what 1$ can bring you: intricate lubricated plastic gears, a DC motor, a small PCB with the voltage stabilizer, not to mention the plastic housing and the strap. Pity for all the work those asian manufacturers put in it. Seeing that PCB made me think that maybe some of you want to see the schematic also and with a little help from digikey's Scheme It here you have it in all it's glory:

Quite rudimentary but it's good enough for the budget involved.


Features?
- It has a red LED that lights up when you spin the crank
- It also has a strap that you can.. do whatever you want with it

Pros:
- Gave me something to write about in this article

Cons:
- It's a "junk out of the box" kind of thing

Fotomate LP-01, LP-02, LP-03

Since I am trying to sink deeper into macro photography and an usual macro lens ain't macro enough I thought about the other tweaks of the trade: reverse lenses, extension tubes, lenses back to back. All these require a focusing rail for ease of use.

This wasn't the only need for a focusing rail. I recently purchased a motorized astro head that I plan on integrating on a bigger project I'm working on and didn't have the chance to post yet. But to stay on track, the need came for such focusing rails and at first I tried the usual approach with well known brands and big stores. Sadly, as with most photo equipment I was shocked about the prices involved. I'm pretty mechanical open minded so I have quite a clue about what a focusing rail involves and it's nothing close to justify the hundred of dollars prices.

So.. same as before, I turned to my Chinese friends for a cheap bail out. One day or two on ebay and I put my order, three of four weeks later my rails were at the post office. I had a hard time determining what was the proper length needed and since price wasn't a limiting factor anymore I got one of each model that was worth it.

They're labeled Fotomate LP-01, LP-02, LP-03, where Fotomate is just a showcase name for Jiangmen MIDAS Hardware Electronics Co., Ltd. All rails come in plastic blisters, all rails have a central tripod mounting hole of 3/8" with an included 1/4" adapter. All rails come with two 1/4" camera fixing screws and all rails share the same pinion wheel - gear rack system for the rail movement.

Now for the hands on impressions: well, can't say I'm blown away but I didn't expect to be either. For they're price point they're quite a bang for the buck. They're now overbuild, they're not super quality and they're not highly engineered either but for a home user like me.. they definitely do the job.

I made a little video unpacking and playing a little with the rails. What I wanted to point out in the video but didn't have a mouth to do it was that:
- the paint job isn't the same on any two rails, not that it matters that much
- the paint job isn't that good either. Here and there the paint is chipped away and in some places clogged up, not affecting the functionality though
- the roll and lock screws both have quite a big play. It doesn't seem to affect their functionality at all but I don't know how this translates after 1 year of use of more.
- being a rather direct drive system, if under load and on an angled position the rail will slip if not locked. Since the lock mechanism uses a plastic pad between the rail and the base plate, the lock screw can be used  just like a friction screw on a tripod ball head, so you can limit that slipping to acceptable levels. Either way the rails has end stops so the base plate can't fall of the rail.
- because of the relative big teeth on the rail, the movement is a little jerky and needs a little friction from the lock screw if smoother positioning is required.

So if I draw the line.. Am I happy with the purchase? Yes. Would I buy them again? Yes. The only question left to be answered by every user is if the quality provided is enough for one's standards. For me it is