Just got back my first order of dirty pcbs, all up excellent. Anyway, plenty of others have espoused the greatness of dirtypcbs so I won't go into depth, but I haven't previously seen mention of how minimum the silkscreen text sizes can get.
I made some text on my pcbs really quite small, fully expecting it to be a miserable mess, but in fact it's beautifully sharp.
In the text sparks.gogo.co.nz shown below, the width of the lines in the characters is approx 6 mil (approx 0.15mm), this is a "Vector Font Size 4 with Normal line width" in Diptrace. The total height of the letter k is approx 46mil (approx 1.15mm). It is very clear and readable, and looks roughly the same or a bit smaller as the ID number printed by the board house.
FWIW, 5x5 protopack, I lucked out and got 12 boards, all look good, only thing I noticed was a very slight difference in registration between sides (that is, drill hits on one side are perfectly centered by mk 1 eyeball, on the other they are slightly off center, nothing major).
There are plenty of resistor network finders out there, but I never came across one that worked off "just what I personally have to hand", they assume you have at least a full E24 or better set - if you are a cheap bugger like me, you don't keep a full set, just more common values in a few decades.
So anyway, long story short, I wrote my own equivalence finder that considers only those resistors you actually have, and figured somebody else might find it useful, so I put it on the interwebs - Equivalent Parallel Resistor Network Finder Using Your Personal Stock List Of Resistors (it's a mouthful, but trying to be friendly to the future googlers here).
Caution, you should use Chrome for best results. Firefox works as long as firebug is disabled. No idea what IE will think of it all.
Scroll down the page to enter in the base values you have decades/partial decades of. Select the number of decades you usually keep. Enter in any holes in your decades. And any bumps outside of the decades. You can hit the "Save (sort of)" button and bookmark the result for next time.
Once you've described your resistor stock, you can search for a desired value (you can enter it in the usual various styles people use - 1.0, 3k7, 1.5M, 0R5, 0.5R, 762913 ... you get the idea), specify how much error you will tolerate, choose when the search should give you a less-precise but less-resistors solution, the maximum number of resistors per stack, and if there are no solutions within your error tolerance you can select a Last Resort option to look for a solution of two parallel stacks in series.
NB: The first time you hit Search it builds an array the possible stacks, so that can take a few seconds depending on the Maximum Stack setting.
Anyway, there you go, hope somebody else finds it useful :)
The Taobao seller also has a mini version of it, and sells built up in cases also...
The silkscreen (and a display on the 1602 LCD) says it is "BG2001_V2" "By_LET".
Anyway, supposedly (in so far as Google translate would allow) this supports standard Hakko 936 irons (and the T12 type which seem to be the most common in China for some reason), also supports 4 presets, automatic sleep, DC input in a wide range, input via encoder or buttons. I have finally got around to wiring it up as best I can figure from the diagram. It detects a Hakko 907 handle as a 936 ok, and drives the element, unfortunately it just doesn't seem to be able to read the thermistor at all, the iron temperature readout seems locked to the ambient temperature (but the iron heats up in a matter of seconds, it's not a delay thing, the element is being driven flat out at 100% PWM).
It DOES know the thermistor is there, if I disconnect it, it reverts to T12 mode. I tried putting a pot in place of the thermistor connection and twiddling that flips between 936 and T12 mode around 300 Ohm I think (more becomes T12 and the iron temperature indication changes, less becomes 936 and the iron temperature display seems to lock to ambient [and drives at 100%]). So far as I know the handle's thermistor is working - at least, the resistance across it changes with the application of heat to the tip of the iron. I think the 907/936 irons are just a simple thermistor.
What I suspect, is that the controller simply doesn't support 936 handles (907 etc) properly, since it seems everybody in China uses the T12 based irons. All the images show T12 irons in use, none show 936. So yeah, a warning, if you want to use a Hakko 900 series handle, these controllers possibly don't work as best I can figure, despite what they sellers say.
I guess it could be a configuration thing that has to be twiddled - if you hold the encoder button when powering up you enter a config mode where there are 7 different options you can change, some of them I have worked out, but some are just a number without any sort of notion was to what they do (if anything). So, if anybody has bought one of these (I see the ebay seller has flogged off a few of them) and had success with a 907 handle, please post below!
So I wanted to put one of my handy dandy LM2577 DC-DC SEPIC's in a box with some binding posts. Being of an incredibly cheap-ass nature genetically there is no way I'm shelling out for an actual project box if I can avoid it!
So, I present, Corflute as a simple DIY project enclosure material, all you need is hotglue, and a knife :-)
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Corflute is the (genericised brand name) fluted plastic board which real-estate and event type signs are made from. Indeed, I made my simple square enclosure out of old signs which I got for free, real estate companies usually give away their old signs, or just grab an event sign which has been left around after the date. Even if you can't find some old signs, this stuff is ridiculously cheap to buy.
I used 5mm variety, the really nice thing is that it's 5mm square, that is, each flute is 5mm on each side. This makes it very easy to cut to just the size you want, and makes the corners bend really nicely, just cut out the 5mm slice from one side of a flute, then bend, you get a nice curved corner.
At the join edge I left a 5mm flap to cover the end, then just hotglued togethor. For the caps on each end of the cube I cut a square of corflute to fit exactly inside the box, with a flap 5mm larger in each direction. The bottom I glued in, the top I left unglued, it's a tight "snap" fit to allow for access.
To hold the board, a couple of ledges were hot glued inside the box on which a shelf sits that the board is screwed to. I grabbed a handy spray can and painted the box before final assembly.
Working with corflute is very quick and easy, and it's also very strong, and doesn't look bad either, even for a ham-fisted fellow like me.
Has anybody seen Via rivets which will fit a 0.8mm drill hole?
I bought a few which were advertised as 0.8mm, but they turned out to have an outer diameter around 0.88mm and so would require a drill hole of at least 0.9 really.
Searching for 0.7mm via rivets or smaller is not turning up anything at all, well not from the chinese sellers on ebay or taobao. Perhaps they just don't exist at all?
Hi all, long time lurker (and occasional blog commenter), first time poster.
It was here on DP that I first heard about Taobao for electronics buying and I have made 3 orders of stuff from there to date, with a few of us having done so I thought that it would be a good idea for a thread about how we have found the agent service. This is not entirely altruistic because for my next order, I want a different agent.
There are other sites which have a few reviews of TB Agents, but electronics components is such a different area than [things you put on your feet (avoiding the new user bad words), tea, knock off labelled bags...] that we have specific requirements (and much more trustworthy reviewers!).
So let me kick off with my experience of...
Taobao Focus
I made my three orders using Taobao Focus.
The first order, in December, went well, it was a small test order about 70 USD total or so, nothing very much, some screw terminals, binding posts, fuse holders, right angle strips, and a pair of meter leads.
The second order, what a mission getting things that were not "out of stock and seller doesn't know when they will get more" of course that's not to do with the agent and given it was end of January perhaps understandable with the chinese new year around the corner. But anyway, Focus were (silently) patient while I pieced together replacement items from other sellers to add to the order (mainly so it wasn't too small to be worth shipping with all the missing items) and it all came out in the end.
The third order, things seem to be coming apart a bit, processing has been a bit slow in general, one of the items wasn't in the photos and took a couple of days to resolve that, and worst is they over charged me on one part of the order (and refused to fix).
So the experience with Taobao Focus has been pretty varied, from excellent, to a bit dicey.
Good: Photos before shipping included. No paypal surcharge. EMS rates are cheap. The packing of items was good - but not static safe, I didn't buy anything that is very static sensitive intentionally, certainly no bare ICs, I don't think a general TB Agent could be trusted for that.
Bad: The main problem they have is that their cart system doesn't handle fractions of a yuan. If you add something to your cart that is 0.1 yuan, it rounds up to 1 yuan, add a 1.5 yuan thing and it becomes 2 yuan. You can specify the "requested price" as the correct amount and in theory they are supposed to purchase at that requested price and set an adjusted total, or if they can't get it at the price, cancel the item and let you know.
The trouble is two-fold, firstly, the "first payment" is the rounded-up figure, for an extreme example in this last order I purchased 200 Via Rivets for 0.05 each, that's 10 yuan total but for the first payment I had to pay 200 yuan to order them, the adjustment being 190 Yuan contributed towards the shipping, quite annoying. But the bigger problem is you are having to trust them to do that adjustment, as I have seen in the latest order it's not a sure thing, one item I ordered a few of was 0.1/item, I specified that it was 0.1/item, and they still charged me 1/item (they should have cancelled that item if it was more than 0.1/item) and when I asked them to fix it, they refused. In this case I'd only ordered a handful so I just let it slide, but if it was say those rivets instead, that would have been a much harder pill to swallow.
Poor ability to communicate. The live chat is so-so. The in-order communication is very minimal. Email notifications of order status is very hit-and-miss if there are any. I tried to get that mis-priced item (1/item charged instead of 0.1/item) fixed by using the live chat support after the in-order communication request was refused, which was painful and unsuccessful, I don't know if they didn't understand, or didn't care, or both.
Conclusion: Definitely do not recommend Taobao Focus if your item prices are fractions of a yuan due the cart and pricing issues it has. For pricier items where that doesn't matter, I'd give Taobao Focus a slightly hesitant thumbs up providing that you login to the site and check the order status at least once a day (because you won't get emails half the time), that you double check the totals of your items as soon as they have gone to ordered status (especially if there is an adjustment expected to be made, calculate the adjustment and check they calculated it correctly), and that you don't need to give much of any sort of special instruction about an item.
