Chinese RTL-SDR Kit Question

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nay27uk
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Chinese RTL-SDR Kit Question

Post by nay27uk »

OK so had this blooming chinese RTL-SDR kit for over a month now and finally have some free time to start building the kit, I am starting off with the SMD's but I am lost.

In the kit with the SMD parts is one on its own, black SMD component that looks to me like a SMD LED (this thing is tiny, less than 1 mm and with a clear window on it each side with a green dots).

Can anyone that has built this kit tell me if this is in fact a SMD LED and if so how the hell do I determine its polarity? I have used all of the magnifying glasses I have now even one that is 500X and this thing is so small I can work no markings out apart from on the top and bottom it has a green line one side (Underside) and a green dot the other side (Topside).

Anyone got any clues please.

On the board at a SMD spot is screen printed LED-R I am asuming it goes there but what about polarity?.

I cant find any info on the net about it having an SMD LED its all about the ordinary LED that mine also has.

I will try and get a photo of this thing but it is that small that I am unsure how good a picture I can get on the only camera I have, My phone.
Last edited by nay27uk on 12 Dec 2016, 16:24, edited 2 times in total.
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nay27uk
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

OK here is some picture of it.

The first Picture is its top side.

I have highlighted (IN RED) the best I can its sides so you can get a grasp of just how small it is, this is taken on a 16Mp phone camera that is zoomed right in @ 100% and is about 1CM away from the item.
topside.jpg
The Second Picture is of its Underside, again the zoom etc on the camera is the same as in the first picture.
underside.jpg
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

OK as I gathered it is a LED and the cross thingy as seen in one of the above pictures is its annode
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Re: Chinese RTL-SDR Kit Question

Post by stanogs68 »

jesus nathan i would need binoculars and about 10 valium to stop my fat shaky fingers to solder on that ,haha
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Re: Chinese RTL-SDR Kit Question

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Mate I am realising now that building one of these is not for the faint of heart mate.

They have deliberately supplied the smallest SMD components known to mankind, they could quite easily have made the pads a little more spaced out and supplied 1206 SMD parts instead of the 0402 or even by the looks of them the 0201 size that they have supplied.

Just for comparison's sake a 1205 is 1.5 mm a 0402 is 0.5 mm and a 0201 is 0.3 mm, I blame the slanty eyes, the chinese must be able to see minute things better than the rest of us due to having slanted eyes (no offence intended, but come on bloody 0.3 mm)

I fully built a Softrock Ensemble II HF KIT (LINK HERE) that was easier than this thing to build and that had some small components.

I am building this thing with just a 30W soldering iron with needle tip, a helping hands with one 20X Magnifier and my GF's makeup tweezers because my proper electronic tweezers have vanished, and thats all I have.

When I built the softrock I had the same gear bar the helping hands.

It would help when doing stuff like this, to not be a right old shaker like me, my bloody hand is shaking all over the place (it's like I tell my brain OK Steady Now but my brain laughs and says YEAH RIGHT and I shake even more) and I have lost a less than 1mm part on the floor more than 3 times now and they aint easy to find once dropped, you so much as cough and these things go flying.

20 minutes after starting I have 1 X 33nF capacitor on, I have to say that it is one very neat looking 33 nf capacitor considering the kit used, I will post some pictures up of it at build intervals.

I am working on the SMD's first, then the not so SMD's like the USB and antenna sockets.

I will then go onto the through hole components.

Finaly I will do the actual dongle bit as I am waiting on some antenna converters to come from china so that will probably bee about march 2017, I cant build the whole thing before I get them as I will have no SDR.
Last edited by nay27uk on 14 Dec 2016, 11:38, edited 4 times in total.
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Re: Chinese RTL-SDR Kit Question

Post by stanogs68 »

might have finished for next christmas then lol ,good luck :thumbup:
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

stanogs68 wrote:might have finished for next christmas then lol ,good luck :thumbup:
Yep all in it will probably be March as I am waiting on some antenna converters to come from China
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

OK here are the tools I am using.

My Hands (complete with very bad dermatitis).
IMG_20161214_115252.jpg
A helping Hands (blu tacked to the Worktop in the kitchen (because the **** keeps moving around)
IMG_20161214_115303.jpg
Soldering Iron
IMG_20161214_115310.jpg
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Last edited by nay27uk on 14 Dec 2016, 12:35, edited 6 times in total.
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

Soldering Iron TIP
IMG_20161214_115325.jpg
IMG_20161214_115330.jpg
Yeah I know it is bent but it has had about 4 years of use
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Re: Chinese RTL-SDR Kit Question

Post by stanogs68 »

How many bits have to solder on mate
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nay27uk
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

Erm not sure mate but in the whole kit I think it is close to 20 or more things.

The Softrock Ensemble II I built was at least 40 or more.
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

Will post more pictures later when I get that silly small LED on
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

Well I finally got all the SMD's on the board, these things were tiny and the one in the far right top corner circled in red an SMD LED was a nightmare job.

Some of them don't look very straight but with the size of these parts and with only the kit shown above it is very hard to get them straight plus the board your soldering to is like an ice rink one tiny movement and parts are skidding all over it.

Because of the small components and the zoom on the phone it looks like my soldering skills are shameful.

I am not looking forward to doing the two pieces of wire that have to be soldered to the RTL chip legs.
IMG_20161217_080521.jpg
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

Oh I forgot to add that the 2 parts circled in the picture below seem to be magnetic, for some reason, so if you intend on building one of these kits then bear that in mind.

Not only are they very small but with them being magnetic and sticking to your tweezers it is very hard to get these aligned on the board and soldered straight without them moving or sticking to the soldering iron, I lost count of how many times the LED (top right) ended up attached by magnetism to the tip of the soldering iron.
IMG_20161217_0805211.jpg
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Re: Chinese RTL-SDR Kit Question

Post by nay27uk »

To sum up this far I am not happy with the build so far.

The SMD's are not straight enough for my liking and my soldering has been 100% better on other kits that have SMD parts using the same tools bar the helping hands (in fact the helping hands has caused a few problems (magnifying glass leaves no room) and at least 4 of those caps were soldered on using nothing more than my own eyesight).

More to come as I progress with the build.

Next will be the other not so SMD parts like the USB and the Toroid then the coils

A little note on air core coils.
You see many people on videos making kits or projects that do not take the ends of the air core coils into account, if you wind an air core coil properly each end of the coil is a 1/2 turn so together this is a full turn, so taking this into account if you need an air core coil of 11 turns then the full amount of turns you need is 10 + your 2 end turns at 1/2 turn. 10 turns + 2 half turns at each end = 11 turns
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