SMT variant of 2N3904 NPN transistor? Answered

Im looking for a SMT equivalent of a 2n3904 transistor. I found one on digikey that might be similar, the MMBT3904. Is this correct? Many thanks- Astroboy907

Question by astroboy907   |  last reply


eagle - how to put smt components on bottom layer

Hello all. I'm trying to lay out an eagle pcb with both smt and conventional components and I'm trying to make it single -sided. Does anyone know how to put an SMT part on the bottom layer? Thanks

Topic by thegruffalo   |  last reply


Good soldering iron, w/ fine point tips, less than $50? Answered

Hey all- I've finally decided that my soldering iron just plain sucks. $3 harbor freight irons just dont cut it anymore :) (dont really recommend them. Solder eats away at tip). So- the question. I need a good, high quality soldering iron, preferably fine point (or has fine point tips available). I would like one under $50, but I'm looking for around $30.  Do you think I need to get one with variable temp? I am using lead free solder, but I may do some (not a ton) of SMT work. Just as long as it works, and has a quality tip I am good :) Thanks for your answers -A907

Question by astroboy907   |  last reply


How do the buttons on a calculator work?

My calculator has these black lines (under all the buttons) that are very close but not touching in wavy designs right on the PCB. How do these buttons work? Is there a way I hook up a SMT push button to this? Like I mentioned before, both my calculators have these black traces. Is this a covering over the copper? How would I get to the actual copper? Do I try to sand off the black?  Thanks!

Question by HavocRC   |  last reply


I need help identifying SMT components of a laser pointer driver. Answered

I recently dismantled my 5mW green laser pointer because I was sick of feeding it AAA batteries. I'm using 4 18650 Li Ion batteries now. I found a little trim pot that increases the power output and when I turn it up, two of the driver components get really hot. I would like to build my own laser driver based on the original, but I need help reverse engineering it. I've attached a few photos, including the circuit I determined so far. The node voltages when the laser is operating normally are included in blue. The two main (I'm guessing) components are marked Y2 and MY and I have no idea what they are. MY becomes very hot at high load. Please help me ID them!! Oh right, and I had to put the big resistor on there. It's a 1Mohm. Somehow it's necessary for the circuit to turn on without the pointer body. It's connected from battery positive to the bottom of Y2.

Question by laserjocky   |  last reply


Has anybody tried painting LEDs?

Because the colors available just aren't enough and we want more. *glances at collection of smt LEDs then at collection of nail polishes* The odds of me blowing up an LED or setting something on fire are slim, right?

Topic by aliasjanedoe   |  last reply


Can someone help figure out this Analog Devices chip? Answered

I recently aquired a handful of chips labeled Analog Devices ADTL 84. It's a 14 pin SMT part. Any ideas about what this is/does? I've done extensive Googling to no avail. I can add pictures later if anybody wants. Thanks in advance!

Question by Erik J   |  last reply


October 12th Grand Opening-Fremont CA

Schmartboard, The World’s Greatest Electronic Circuit Prototyping System, has relocated to the historic Centerville section of Fremont, CA. Join us on October 12th from Noon to 3 P.M. as we celebrate our new location. • Come and meet and have your photo taken with Oakland Raiderettes: Chanel Nichols and Ashley Brown • ***Hand solder a chip using Schmartboard’s patented “EZ” technology which makes hand soldering fast and easy • Contest with prizes from Schmartboard, other technology companies and local Centerville businesses. • Special offers not available to the general public. • Giveaways, Food SchmartBoard is the destination for people who want to hand solder surface mount (SMT) components. Are you an engineer, technician, educator, student or DIY hobbyist who has avoided utilizing SMT components? Those days are officially over, because with SchmartBoard practically anyone can hand solder SOIC, QFP, PLCC, QFN, BGA and discrete surface mount components. More Details

Topic by nealgb   |  last reply


Smallest thing to make an LED flicker?

I'm just wondering what's the smallest thing I can use to make an 0603 smt LED flicker (not blink/flash)? I love the look of simply having a bad connection to the battery, but sadly that's not a very good or reliable method. I suppose I could use an AVR chip, but I've never done that before an it looks expensive to start. Any chance there's something like a flicker resister that I could just solder into my wire?

Topic by aliasjanedoe 


Eagle design question? Answered

Hey- im trying to design a single sided ,mostly smt board in EagleCAD, but I am having some trouble. I want to make the program to alooow bottom side jumpers, but have them always terminate on the top layer (so pretty much jumpers underneath the board). I have some pads or header pins pointing down, but the wires usually connect to those because pads are on both layers.. any way to fix this?  I really would not like to manually route every trace myself.. Thanks!

Question by astroboy907   |  last reply


Wildlife CCTV repair question

So, I accidentally agreed to fix a friend's IR wildlife camera,  which has had the cable mostly ripped off. I have three wires to solder back to a crowded circuit board, but I don't know which goes where, and I've never done SMT soldering like this. I've tried finding diagrams or manuals, but I haven't managed to yet. Does anybody have any ideas? (In the photos, the only wire soldered in place is the black one, and the jacks are the end of the cable away from the camera)

Topic by Kiteman   |  last reply


Arduino Motor Control Shield

Hi! I am having trouble with two motor control shields. 1 - Arduino motor control shiels                                               // Hole-through devices  2 - Adafruit motor control shield V2                                         // SMT devices My problem is the installing the libraries.                                // will not compile,  need an AFM !!! I have done this before, but every now and then I'll get stuck or confused doing it.                    I've read the tutorials and seen the Youtube, what can I say I'm still stuck.                          // simple get hard sometimes I normally build my own circuits and programme them, but lately, I'm buying them already made and most of them need a library. . If anyone can help me I sure would be thankful. Thanks Frank G.   

Topic by 56Frank   |  last reply


I rebuilt a battery and it didn't work. why? Answered

Today i got the 12 batteries required to rebuild the battery in my powerbook 190. i dont know the condidtion of the parts inside the laptop, but it must still be in a somewhat working order because when i hooked it up to an ac adapter (12v, 15a) before, its power light turned on and it made some noises. it didn't fully turn on though, because it needed 24v, not 12. hoping that rebuilding the battery pack would help, i bought 4 cordless phone batteries, each consisting of 3 smaller batteries and equaling 3.6v. all together that created the 14.4v that is needed to replace the original, acid leaked batteries. i wired them in series to get the 14.4v. I think that it may have not worked because the original batteries were nimh (nickel metal-hydride), and these new ones were nicd (nickel cadmium). Upon observing the internals of the laptop earlier, before i bought the batteries, i noticed some peculiar things: -there were a few spots where some components were added, (eg- resistors, capacitors, jumper wires, all were smt) -a unbranded piece in the battery power area, labeled on the board as XFER1. it is black and has five connections on each side of the component, which seem  to have copper wires attached to them leading inside the component. -no marked fuses on the board. the (apple released) manual for disassembling the machine states "you can blow a (soldered) fuse on the board", but there are no spots where a fx (x representing a number, eg: f1) is present, and most of the smt components in the suspected area are not marked and lok much like the same piece. can anyone help me figure out what may be wrong? the ac adapter port works but the battery doesn't, would uploading pictures help people help me?

Question by zack247   |  last reply


Look here if you need Ideas!!!

Lots of people are asking for ideas for instructables. Here's a few ideas that might give you a new idea. If you have any ideas, post em here, so people can hopefully make em.Tech:* As suggested by Redrev: Take a DVD-Player/recorder that the DVD drive has died and take the tuner and video hook ups along with lcd screen(that shows the channel and dvd section numbers) and connect to the computer to watch t.v. and dvd's ala win-tv.Climbing Robot- a robot that can climb a little stairs of books or something. Or at least crawl.A model of an elevator- you know, you hit a button on a remote, and the elevator rises to that level.Model Train- one of those little trains. Would be cool to learn how to make one.Model Forklift- Its basically an R/C car, but can anyone make it lift a little notebook?Pencil Sharpener? (Electric)Introductions - Theres a lot of big words out there, but most of us have never heard of em. If you're good with something, why not shre your knowledge?FlexinolsmtOffBeat:Weird Uses for satellite dishes- I've noticed how many thing you can do with old satellite dishes. Be creative!Naruto Costumes and accesories (not paper)Dragon Ball Z style effects with smoke- how about pressurizing fog or something to have it shoot out of a tube? Would be neat.A DS Game CaseArtHow to draw Anime Hands- personally I find that hands are the hardest thing to draw. Maybe someone has a little trick to get em right?Bridge of toothpicks- Its a bridge made or little wooden sticks that can hold a grown man. I've seen it in a lot of science fairs, and it would be neat to learn how to make em.As much as I hate myself for doing this, yes this is another post of an old topic I had. Just saying it before anyone else.

Topic by Keith-Kid   |  last reply