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This was partly a way to test my first panelised and V-cut PCB order from an online supplier. It turns out that the $2 for five panels soon adds up as you deviate from the norm.
I decided to make a small square PCB that has a micro USB connector on one side and a two pole connector on the other, with two 10 ohm resistors for current limiting. In hindsight this module could have been more useful if it had a solder pad and PCB terminal block option too. But that's why we make prototypes.
It works, and it means that I don't need to cut up any more USB leads to run strings of LEDs from USB power supplies.
If you want to get a batch of these PCBs made, here's a zipped file that contains all the Gerber files needed. Note that because the site is not currently https you may need to copy and paste the link to avoid weird security warnings.
It's an improved PCB with extra pads and strain relief holes for the direct connection of fairy light wires.
To use the files with a company like JLCPCB, go to their order/quote page and when you click on the "Add Gerber file" button, upload the full zipped file.
The PCB dimensions are 18mm by 18mm (if it doesn't fill it in automatically).
For better value select "panel by JLCPCB" and then type 5 into both the column and row options. That will give 25 snap-apart PCBs on each panel.
To allow for USB connectors with short leads, select 1mm for the PCB thickness.
When choosing a shipping option, make sure you look for the cheaper China-post or airmail options as the default will be expensive express shipping like DHL and Fedex.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.

It's time for a project and the project isn't going to involve these circuit boards that i got from glc pcb. However, i want to clear once again: they are not a sponsor. I don't accept the free offer of circuit boards, i always pay for them and it turned out to be very interesting because their two dollar offer does not always work out at two dollars, particularly in this one where well, let's talk about that in a moment, this Is a five by five array of little circuit boards are designed as an alternative to previous projects, where i've taken the strings of battery object, christmas lights and i've shown you how you can sleeve and solder resistors in after you've chopped usb leads off just to use Them as a usb connector, i thought it'd be really cool to make a circuit board where you can actually just plug the usb lead as it is onto the circuit board, and it's got the resistors and the connector, and it's just a little interface that lets. You connect straight to the lights, so this is the first time i've had them panelized and with the v score, and the v score means that you can just basically you can flex it and they will cut crack along a line, and then you can break it Down further into the individual circuit boards - and it's interesting to note i'd seen other youtubers that shield the glc pcb services and one in particular saying here's how many you can get for your two dollars you can get! You can penalize it with a v score to lots and lots of tiny circuit boards and he was getting loads and loads of circuit boards for the two dollar offer.

It doesn't work like that, if you're paying for them this circuit board here a set of five of these with the extra tooling cost that well the engineering costs for the v score and things that actually came into 7.10 plus shipping. That's fine! That's perfectly acceptable! This one, however, this is for a later project based on a russian lighting effect and it's lots of tiny circuit boards. Not only did it incur the extra charges for the v-scoring, but because the circuit boards are so thin that involves more manual effort, so this set of five circuit boards came in at 23.30 plus shipping, so it came close to about thirty dollars, maybe just slightly over Thirty dollars for this set of five circuit boards, uh, the other youtuber - did not really imply that that would happen, so it's useful to pay for them and uh get the same service as everybody else, but anyway, let's make this circuit board. So this has two 10 ohm resistors, i'm going to zoom down on this.

It has two 10 ohm resistors. It has an output connector and a little micro usb connector. It's worth mentioning. I went for inner circuit board here material here.

So here is the uh calipers and this material is 1.2 millimeters thick, as opposed to the usual 1.6 millimeter thick material and the reason i chose. That is because i got some of these little connectors from aliexpress and ebay different sources, and although they all look the same in the listings, i should scroll out of it here. Although they look the same listings, the length of the pins and the legs can be very variable, so i deliberately this one was the shortest, so i deliberately designed it to actually accommodate this little tiny connector. I like these.

These are micro, usb connectors, but they've got just two pins at the back. It just makes it much easier to solder than the surface mount ones with all the tiny, tiny pins these ones can actually put through a hole and soldered easily right. Let's get back down and start soldering this together and see if it works, i mean it should work. It's only two resistors in series, one, the positive rail one, the negative rail, why two resistors just to spread the load.

It means that if you're running them at fairly high current uh with low value, resistors they're not going to risk getting the resistors exceeding their rating uh notice, the the screen print looks a bit scruffy there mmm it's uh, definitely a bit patchy there as well. That's okay, it occasionally happens. It's not that critical. I wonder if uh, if i'd been getting them as a freebie, if they'd actually done the special service and given you know, taken things that into consideration.

Who knows right? That's the 210 ohm resistors, which i'm just forming by hand now, let's sort them in. Where is the soda there's the soda as usual, i'm just going to hold them in with my fingers at the back, while feeding the soda in so we'll start off with this one, as always, when soldering make sure you've got a nice clean. I like to turn it before use bit. It should be shiny, it shouldn't be matte and apply the soldering iron tip to the pad and the lead and then put the solder into it.

That way that vapor that's coming off is the flux. It's quite important that that boils off while you're actually making the soda joint, because it's the flux that makes them together. This is very hot, actually because uh because me holding resistors in, but that's okay, if you do what some people do and you put the solder onto the iron and then you take it across and try and wipe it off onto the joint. That's how you get bad joints, because the flux is all gone by that point.

Right. Tell you what let's uh do this? Oh, that's getting very hot, very quickly: ow ow, ow, tiny circuit board, that is the perl of tiny circuit boards. Now we can just grip! It from the side, so this is going to be a lot easier. So on goes the other solder connection at the end of that resistor and this one for the end of this resistor.

Okay, they look. Okay, they look fine, they look excellent. Maybe i'm exaggerated by saying excellent, we'll crop those off with these generic side, cutters from ebay, electronic side, cutters, lowest price first on ebay, they're, so commonly used in china that they're all pretty good quality, get yourself a couple of pairs, they're very, very useful. Now i'm going to put in oh, i forgot a component actually not to worry.

I shall go and fetch it in a moment. Now we'll pretend this little connector here which true to form uh. It's goes in a friction fit, but it's only protruding through a tiny little bit. That's annoying, but that's okay! It's enough to solder, which is the main thing.

That's why i went for the thinner circuit board. Maybe i should have gone for one millimeter thick circuit board, but as it is, i can solder it and that's all that's really needed. It's very random. These connectors what you actually get they're kind of a specialist connector, the little micro usb 2 pin through hole.

It's not normally used by companies, that is the connector, and it looks quite smart uh right now for the little other connector, which is going to mate onto the molexy type connector one more, i'm just going to grab that there we go. Oh, there is a bug in my drawer. There is a bug in my drawer. It's actually found its way into the drawer.

That's quite annoying so get rid of that bug later um. Now. This is where this connector goes on, with a little uh alignment and latching. Well, it's more for alignment, doesn't really latch at the back here and it's something i didn't really think of.

I measured these pins sideways and then put a round hole and it fits it's. A nice friction fit it's a very snug fit, but in the hindsight i should have measured those holes directly because that's the largest diameter so to speak, of a square pin, okay and now we'll solder. This in this is so easy to make you could, if you were making up a few of these, just do them on the panel before actually snapping them. Apart.

In hindsight, you know that thing that you submit the circuit board from manufacturing. You suddenly realize what i could have done. I could have moved that little symbol up there that one up there, i could have put great big pads here and you could have soldered. These leads directly onto the circuit board a bit like a little current limiting adapter, but i didn't think of that not to worry so this is it.

A usb cable can now physically plug into this circuit board, and then it has the current limiting resistors and then it puts out on this connector. So now we bring in the lights and this time i'm going to be featuring george home. These are very nice. These are from a supermarket in the uk called asda, and the nice thing about string lights is they're, pink purple and blue.

That's really nice! It's a good color! So let's get rid of this huge ugly label, we'll just cut this off completely and the child safe. Uh battery box with screws in it how annoying so, let's crop these uneven length and i shall strip them using this generic pair of cheap wire strippers. This these ones are made by draper no.ws6. I presume that's the model number they're, just generic wire strippers and now, let's check the polarity so to check the polarity.

I recommend just getting uh lithium button cell hold the wires on either side if the light as they are, then the wire that is in the big side. The positive side is the positive i'm going to put a red dot in there. I'm going to get a sharpie and i'm just going to put a sploot of red on it. That is the positive now i'm going to handle that before the sharpie has dried and get red ink all over my fingers.

This is where the project suddenly gets very expensive, but there's other options you can solder into these little crimps. Now the connector i'm using is typically called its online name is a kf2510 kf2510 very common connector. I really like these connectors i've. Always i've used them a lot.

I probably started using them because, with rapid electronics, it's probably the most affordable little circuit board connector they had and at the time this crimping tool wasn't that cheap but still affordable compared to the official type tools. I really desperately want to twist these wires together before putting them in. But you can't do that with crimps, because these little crimps actually wings that fold round like the mcdonald's m and actually they make golden arches and they crimp into the mars, and they part them into two little clusters. If you twist them together, it interferes with that and it can actually cut some strands.

It's very hard to have it doing, though i did it so long. I never really had problems, but hey you know. What i'll do it the proper way i'll be a pro in goes this crimp when you first start crimping things like this, the first ones are pretty tricky until you get used to it and then it's plain sealing and you can stamp seeing that i'm going to Mess it up now, but it's plain sailing after that, once you've got used to them and you can make the crimps quite easily now traditionally i would usually put the positive, which is marked red in here and the negative in here. I've just put that set of a crimps on top of something making creaking sliding noises.

That is it. Let's try our system out. So here's a little usb power bank. You could use a plug-in usb power supply.

Is it going to work, let's uh zoom out here? It could be a disaster, it could just not work. I chose the two 10 ohm resistors, just because that's a good value for a typical current limiting option there. It is in hindsight it might be an idea to use the right right angle, connector, but this is it it's uh, it's doing the job and they do look bright. They look pretty damn good.

Actually, nice colors. What is the current uh flowing through those? If you want to know the current flowing through a circuit without actually putting the meter when you put the meter in line, it adds a resistance in this current range, there's a way to measure the uh the current through resistors, just by measuring the voltage across them. So these are 10 ohm resistors by measuring the voltage across them. I'm going to turn this down to the 2 volt range by measuring the voltage across a 10 ohm resistor.

It is 1.06 volts and you can work out the current through it. I equals v 1.06 volts divided by the 10 ohm resistor equals at 106. Milliamps is flowing through that circuit that, if you're using, if you've got a very low voltage differential, sometimes the on particularly in the low current ranges, the meters their internal resistor can act actually had enough resistance to actually seriously affect the current so where i'm at. Whereas i measured well, let's try that let's try that, let's see what uh the meter measures, if i just unplug this and i'll just make a little adapter up right now and we'll put the meter in series we'll see if it comes anywhere close to that one Moment please and continue so putting this little dinky meter in set to the 200 milliamp range.

It has skewed the reading by about 5 milliamps, so it's showing 100.9 milliamps. Now, let's put in the original meter that measured about 106 milliamps. If i remember correctly so i shall plug this into the comm. I shall plug this into the micro amp milliamp.

I shall turn it round to dc 200 milliamps and i shall inject the meter in series. After tightening up these leads, i could actually put the crocodile clips on, but i'm not going to what's this going to do. It says 88.6 milliamps, uh, that's just being affected completely by the value of the resistor inside different meters, so the most accurate ways to measure across one of the resistors in the circuit is also very easy, and it will give a really accurate current indication. Uh currently doubt remembering that the current connections are pretty much a dead short circuit over to com.

Apart from that, resistor always go back to your normal voltage reading settings, so that is it. The project is complete. I'm just going to put this meter down and then come back over to where the microphone is um. Then i'm gon na pull that out there that out there and just uh stuff this connector on here and restore the marvelous asda christmas light glory, but now running from a usb power bank or a plug-in usb adapter.

You don't have to worry about the batteries. This little circuit board takes the standard usb lead and lets you either run them for the power bank or a plug-in power adapter without worrying about the batteries at all and there's 20 leds here that say: 100 milliamps for the 20 leds that works at about 5 Milliamps each that's a fairly decent brightness, but that this will run up like a hundred leds at say one milliamp, which is usually still quite bright as well, but there we go project complete. I think that works out quite nice. It's a very neat little circuit board and it's very easy to build.


13 thoughts on “Usb to led string pcb prototype build”
  1. Avataaar/Circle Created with python_avatars Hola! Boris S. says:

    Clive and Elves (as it's Christmas Time) I know of a UK circuit board manufacturing company near me are you interested… Although their internet site is not as good as jlcpcb… they need some tweaking..

  2. Avataaar/Circle Created with python_avatars Marinus says:

    I've never been able to make use of the 2 dollar offer, maybe it's because I live in the Netherlands? It always turns out more expensive, no matter the type of board I'm choosing.

  3. Avataaar/Circle Created with python_avatars Thomas Tallis says:

    Thanks for getting out the very near calipers! I've have a pack of new batteries sitting on my work bench for a month, totally forgotten why I bought them. My caliper died the very moment I need it the most 😛

  4. Avataaar/Circle Created with python_avatars Daedalus Young says:

    The $2 panelised boards used to be a thing, but people started abusing it and ordered many boards for $2, so they've nerfed it. For larger boards, say 5×5 cm or so, panelising them up to the maximum allowed $2 size of 10×10 cm actually doesn't give any advantage. 4 panels on a 10×10 board, times 5 boards gives you 20 smaller boards, but it costs exactly the same as if you'd just order 20 5×5 cm boards. Obviously they had to make that change, if a lot of people aren't paying for 20 boards, but still ordering them.

  5. Avataaar/Circle Created with python_avatars Cream Of Botulism Soup says:

    I stopped using cheap flush cutters after one of the jaws broke off and flew into my face. I wasn't doing anything too extreme with them, just cutting off some supports from a 3d print.

  6. Avataaar/Circle Created with python_avatars leewot says:

    Clive – you need some ‘crop & bend’ cutters

    They’re what we had as a standard tool for hand fitted components at Plessey- that were fitted after the surface mount and wave solder process- after removing rubbery solder resist

    After ‘crop & bend’ the components remain in the board when you flip it. Avoiding the need to burn your fingers.

    Although having bent leads does make them harder to desolder if you need to do further work

    We also had a ‘stylus’ tool custom made in the factory too shop from a stick of circuit board with a track that went around the ‘nib’ edge – it was used to bend over pre-cut component leads on things like I.C.s etc

  7. Avataaar/Circle Created with python_avatars dglenn247 says:

    Maybe already said in a comment. I think you should do a test. Order the same exact PCB designs from a few places to compare and/or buy from just one company that you buy one set yourself and get the other set supplied on a sponsor spot.

  8. Avataaar/Circle Created with python_avatars Alex Fedorov says:

    Isn't it a better option to go for plated holes instead of single sided PCBs? The price will still be the same, but you don't have to worry about lead length, joints will flow anyway.

  9. Avataaar/Circle Created with python_avatars GJToken says:

    My 2¢ / suggestions for a later revision, I'd definitely go with the right angle connector, and maybe do a 2 sided PCB with the resisters on the reverse as surface mount, that way you could create a slimmer profile that would almost align with the USB connector, perfect for a short length of heat shrink if you wanted to give things a little protection. A tiny side mounted switch (or option for one) could also be handy.

  10. Avataaar/Circle Created with python_avatars Michael Jantzen says:

    JLPcb is quite a bit easier to work with that other company YouTubers push. It's almost a Chinese standard to lure you in with one price and get you with all the add-ons – it would make me a tad more upset if they weren't so good at what they do however.

    OshPark which is a local company for me does even better but they are quite a bit more expensive.

  11. Avataaar/Circle Created with python_avatars Grayson says:

    Our shops experience with jlc has been good. But their smd parts have always come installed backwards and random. We now use Oshpark, made in USA so no more exorbitant customs charges, which I recommend everyone, and they come in a pretty purple!

  12. Avataaar/Circle Created with python_avatars 21palica says:

    Watching Clive work, while also listening to his walkthroughs in that calming voice, makes everything he is doing so clearly and easily understandable. This is so important when trying to recreate something that he made by yourself, because it gives you much more confidence in your work. At least to me it does. Thank you for that, Clive! Keep up with your great uploads!

  13. Avataaar/Circle Created with python_avatars event-horiz1 says:

    Hey Clive, have you done a 'voltage & current limiting device' 101?
    Which cap, diode, transistor, resistor to choose, how and why.
    I always seem to hear references to limitation but sometimes it's capacitors, sometimes resistors & sometimes both. Or "insert a diode in line to drop the voltage".
    Seems to be a lot of options. Have you covered this already or do you fancy doing an updated breakdown with pointers to more resources? 😊

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