How exactly does an N-P-N transistor work? Answered

I need to know about this topic to the core, like from where the electrons flow, which one is heavily/moderately/lightly doped, why electrons flow from that direction and not the other, etc. thanks guys!

Question by ankur2893   |  last reply

need help figuring out what these chips are good for

Im kinda new to electrical components i can follow a picture and put things where they are post to go but figuring out what the components are for no clue i'm currently working on making a 3d printer and was hoping that some of the these components that i found can be used for anything useful.  so heres the list of the chips LM741CN rca 832 P109 DM7473N  7945C  SN7475N MC14093B   CP   7939 ALSO MODEL Z240D10 SOLID STATE RELAY 3-32 VDC CONTROL TURNER ASSY 510-310 DRILL510-311 ITS A BORAD

Topic by MichaelD136   |  last reply

Voltage regulator Design Problem?

 Ah, voltage regulators. Easy Right! Not this one. I am making a voltage regulator like for an automobile regulator for a DC generator. (I'm replacing the old DC generator regulator on Pre 60's cars) A battery is charged from a winding on a Generator  (20V @ 60 Amps) A voltage sensor on the battery voltage turns on and off a switch driving the Field winding. The Field winding basically "turns on and off" the generator output. The battery is connected directly to the generator. (Why  and Why not is coming up) But when the Genrator's output is lower than the Battery voltage, current will flow back from the battery to the generator winding and discharge the Battery. So I need some isolation between the generator output and the battery. Alternators are easy since it has a bridge onthe output keeping the current from flowing backwards. Old regulators used a relay which burned out sooner or later. So easy, use a diode right? Just put a diode inseries with the generator to the batery. By the way, the "open circuit" voltage on a generator is about 200VDC No! The best diode I can find has a .7V drop at 60 Amps which is 42 Watts of heat to dissipate. Ahhh, so use a FET, They can get down into the milliOhms right? Except for the reverse polarity (and ESD) protecton diode always across the FETs defeat the purpose of a reverse polarity switch. So who out there is smarter than me? What goes inthe box marked ?? Any solutions accepted. Ungefahrt (now neither young or fast)

Question by ungefahrt   |  last reply

How do you substitute a diode?

I'm putting together an order at Small Bear Electronics but they don't have the bat46 Schottky diode.  How would I substitute another diode?  None of their inventory seems to be Schottky.

Question by flagrantfouler   |  last reply

Which optical sensor will be best for rotary encoders?

I am trying to make an Optical Rotary Encoder please can anyone suggest that which optical sensor will be best for good resolution and accuracy...I have made one using Photo diode as receptor but the proble i am facing is that switching is not fast enough which results in a lot of what can be done to make photo diode switch fast or should I use some other sensor(phototransistor or Photoresistor) and please do tell the reason...thank you..

Question by malhotra18   |  last reply

Anyone know how to get samples from fairchild semiconductors? Answered

I tried but it said my email wasn't valid or something like that.

Question by furrysalamander   |  last reply

Remote control reciver help?

I need to replace a part from a remote control areoplane. The part number is 06N03LZ and I cant find anywhere where I can buy one. Does anyone know a online store with the part listed and can they give me a link? Thanks. (it looks like the same one in picture but I cant tell because it is in another language.)

Question by David97   |  last reply

Substitute for Boron in p-type semiconductor?

I am trying to think of ways to make solar panels from scratch.  I can get phosphorus from pee, silicon can be extracted from the rocks all around me, but I don't have naturally occurring boron nearby.  What are some substitutes that can be synthesized from the world without modern factories or laboratories?  Furnaces are not out of the question.

Question by tincanz   |  last reply

Semiconductor based switching with a different power source?

Lets say I want to switch on a circuit, that runs on one power source, with a different power source. I know this can be done easily with relays with the coil attached to one power source and the remaining pins to another power source. However, I want to know if something like this possible with electronic semiconductor based switches too. I am trying to make a USB based power outage detector for my computer that can help me in safely shutting down my computer automatically when I am not there to manually shut it down. A male-female USB extension cable of a very short length can be stripped and the red wire (+ve) can be split and connected to an electronically controlled switch which will remain closed as long as it receives current from an external power source say a wall adapter. As soon as the power fails, the switch is opened. A simple USB device like a flash-drive can then be connected to the female end of the cable and the male end of the cable to the computer. A simple C program will check at specific time intervals if the flash drive is accessible. As long as there is power, the program will be able to access the flash drive. As soon as there is a power failure, the program will no longer be able to access the flash drive and start the shut down process. Do have any suggestions?

Question by raftor   |  last reply

Where can i find the exact semiconductor that matches the kind in an LED, without trying to melt or crack them? Answered

I've been looking everywhere for the same material, but i can't seem to find it. tried to harvest it from the led's themselves, but its near impossible! its a bit smaller than a grain of salt. any ideas??

Question by lutziepv08   |  last reply

What are some recent topics to make an innovative electronics project?

I'm not sure whether i can ask such type of queestions here or not , I am interested in analog electronics,microelectronics,semiconductors .What can be some innovation i can contribut to elctronics. Any help would be recommended.

Topic by jatinbatra   |  last reply

Can i use Copper Oxide to make a Home Made Peltier?

Here's the site .  i thought that i can use Copper(I) Oxide to make a Peltier Module. Peltiers are made up of semiconductor materials like bismuth telluride. 

Question by bhipolito1   |  last reply

Transistor Swithching Voltage? Answered

Looking at this data sheet: How much voltage has to be applied across the base and emitter to switch on a "TIP 3055" transistor? The V-be row is the only thing that looks like it is telling about that, but I don't think that's what I'm looking for (mabey it is?).

Question by Jaycub   |  last reply

sdcard Atari drive Answered

Hello, I am going to build the sdcard arari drive from this website. Will these parts work for my drive? I do not think I need a status led unless I want to know if my device is working. Thanks for any help

Question by jbaker22   |  last reply

Can I use a 2SK2690 mosfet directley with a arduino?

Hi, I want to drive a lardge DC motor with arduino and a 2sk2690 mosfet. I have teasted the transistor and it works. Can I connect the gate to the arduino and have it draw not much current. I want to do this like in the picture but allso with a resistor to drain the mosfet. All I want to know is that will I blow up my arduino with this transistor? Here is the datasheet.

Question by David97 

Hello all friends , I wanna make a DSSC , i need to make TiO2 as Semiconductor ,from which sources can i make it?.

I have a research to make Dye-Sensitized Solar Cell-DSSC and i should make every materials by myself in Lab. how can i make TiO2 and from which sources ? to be more cheap and easy . and what is an alternative material for Iodide ( electrolyte ) in DSSC? thank you for replying and for sharing your knowledge about. :) 

Question by Omid1985 

Bob Pease is dead

Bob Pease, the Analog design engineer who, while working for National Semiconductors,  developed devices like the LM317 regulator amongst many others, died yesterday in a car crash in Silicon Valley. Bob was a legendary figure to any engineer working in the analog domain. He died leaving the memorial service for another legend, Jim WIlliams of Linear technology, who died of a massive stroke last week. Bob was one of the nicest guys in the business, and mentored dozens of engineers in his long career.

Topic by steveastrouk   |  last reply

DIY step up switching regulator?

I have a 6v power supply from 4 D cells that I need to convert into 24v in order to drive a solenoid. Can somebody direct me to a switching regulator circuit that I could build? Alternatively, if someone knows of a semiconductor that I could obtain that would do this, that would be great. However, I have looked around quite a bit and have not found anything. Again, my request is for a 6Vin to 24Vout switching regulator circuit, with about 500mA - 1A output... Thanks!

Question by raykholo   |  last reply

Low power mosfet replacement problem

Can anyone help me identify a substitute for a mosfet? It is used, as far as I can tell, as a low power DC switch. It is a 6 legged SMD beastie, part number FDC654 - possibly with a P on the end and is completely short circuit. I'm assuming I've got the right device. There is some information about it here: I can't find anywhere to buy this component as an amateur, and don't know enough to work out a suitable replacement. Can anyone help?

Question by throbscottle   |  last reply

Flexible LEDs to boost biomedicine

Nature News is reporting today on the development of thin flexible sheets of LEDs which could be used for medical diagnostics, or even implanted in the body to use with light-activated drug delivery.  Besides these uses (obviously cooked up for the grant proposal :-) ), the clothing and other DIY uses seem fantastic! The interesting thing to me is that these sheets are made with conventional semiconductor LEDs (surface mount) and the flexibility of the leads is handled simply with extra lead lengths to pick up the slack. The original paper is being published in Nature Materials (Kim, R.-H. et al. Nature Mater. doi:10.1038/NMAT2879 (2010).

Topic by kelseymh 

How do you all become so knowledgeable about electric and computer technologies?

Circuits and semiconductors and transistors and capacitors all confuse and intimidate me so... :-\ I want to know how to turn a walkie-talkie into a communication jammer like in Fringe or create an X-ray machine from an old tube TV like in Burn Notice. Ultimately I'd like to become an FBI agent or CIA spy, but I've gotta start somewhere, so asking how to do electrical engineering on Instrutables is the first place to start I'd imagine.

Question by Pompom   |  last reply

Modifying a DC-DC boost circuit

I'm building a circuit that would run off roughly 7v and convert it to 12v using the LM2577 (LINK). the datasheet (LINK) provides an example circuit that will output 12v @ 800mA. I need a little more power than that. around 1.25 A. my question is that if the 100mH inductor was replaced with a larger one. say a 150mH one, would that increase the current output? i would also replace the 680uF cap with a bigger one to reduce ripple. FYI the LM2577 is rated to convert 3.5v-40v to 12v. any information or direction would be appreciated picture is from the national semiconductor datasheet page 3

Question by stapler117   |  last reply

Voltage regulator circuit design

Hi, I'm trying to make a DC - DC voltage converter. The real purpose is to power an old USB hub in a car. This is because so many of my electronics these days use USB to power them and rather than have a nasty mess of car power adapters I want to use a single 12V supply for the hub and then plug all of my goodies into it. Now for the meat of the question..... What is the best circuit design for using a voltage regulator. I have looked at some stuff in data-sheets and it just seems way too simple. The part I'm looking at using is a National Semiconductor LM1085-5.0. Input voltage 6.5 - 20V output 5V max of 3A

Topic by Sailing_Nut   |  last reply

What components do I need to produce my 3 rechargeable Power-Packs using what ive collected so far ? Please can anyone help ?

Hello & Good day to you all, I'm making my own powerpacks for: a miniature wireless CCTV camera & receiver (Link Below for specs) , and a rechargeable powerpack to charge my laptop (that dies in 15minutes!) Wireless Pinhole Spy Camera & receiver After spending stupid money on sh*t 9 volt batteries (600mAh = £11 EACH) - ive had enough of the crap and absolutely absurdly LOW capacity 9 volt batteries out there (when TODAY's 'D' cell is capable of 11,000mAh !!!) and extremely high cost - i am making a battery-pack to power my receiver and another power-pack for the wireless camera using Ni-MH rechargeable batteries in the following packs: Powerpack 1 (for camera) 6 x 18650 cells @ 3.6v each, 5000mAh {Total Power=21.6v} Output Power Needed:  8v, 200mA Powerpack 2 (for camera receiver) 24 x D Size cells @ 1.2v each 11000mAh ( Total Power= 28.8v)  Output Power Needed: 12v, 500mA  Powerpack 3 (for Laptop) 40 x D cells @ 1.2v each, 11000mAh {Total Power=48v} Output Power Needed: 16v, 4A  I should add that my existing 9-volt (2 new & 1 old) rechargeable batteries are a little-more-than USELESS (Rated @ 175mAh...{USELESS}) as the receiver of my wireless camera drinks the power (juice, lol) at an extremely FAST-Rate... 15 minutes of use and its DEAD. 10 mins of use from the old 9 volt battery. And thats all from a 9 hour charge... How pitiful...Despicable & Disgusting... Now i got the idea to use a semiconductor from an instructable to make a simple solder-fume-extractor... (Link Below!) and also i know that resistors can reduce the voltage and amperage output of a circuit.......... Solder Fume Extractor I have calculated, researched, 'Googled', calculated again, more googling and after 6 months of trawling through the internet to find parts of designs i could hack together to achieve my goals including getting answers from "SO-CALLED-EXPERTS 'In the trade'" and from Circuitry & Electronics Forums (whom shall not be named...) yet they always say, yeah, here's my email address, email me your questions and when i do, they all turn around and gimmi some crap like " have your plan all set-out so what do you need me for ?" AS*HOLES! F*C*ING AS*HOLES!!! - If these peeps didnt want to help in the 1st place, then WHY BOTHER to give me their email address so i could ask them directly for help ? Im now going to give up and finally cry-out --- Please HELP (Again and probably for the last time!) ok ok, enough of the hell's-anger-fuelled-rage-at-"EXPERTS" who give me the run-around.....(Bcoz they're AS*HOLES...) Please please please can anyone help me find the components i need to make my very simple circuits for my battery packs ! I know that the use of a/a few? semiconductor/s (3 pin only) can let in a certain voltage and only output a specific voltage & amperage - i think i'll be needing a combination of a semiconductor and a resistor but i've searched continuous for 6 months now and am now irritated-beyond-belief that i still haven't found what im looking for or that no one is willing to help! ffs! Many thanks in advance for some light on this darn-troubling matter.... Please Help !!! Power-Specification For My Gear: Wireless Receiver: DC 12V 500mA Wireless Camera: DC 8V 200mA Sony Vaio Laptop 16v, 4A Also how do i charge my individual power-packs ? At what volts & amps do i charge them ??? Im already severely mobility-impaired and wouldn't want my life getting worse by any of my battery-packs exploding near me!!!!  Ingredients i have collected So Far: - 12 x 18650 5000mAh Batteries (Li-ion) (i want to make a total of two power-packs with these) - Solder Tabs for battery Packs -Small to medium collection of semiconductors + (plus) & - (minus) output voltages (from -24v to +25v) and from 100mA to 1.5mA amperage... - Heatshrink (40mm, 50mm, 70mm) - 24 x D cells @ 11000mAh - 40 x D cells @ 11000mAh I have no resistors but can order anything i need online if i only knew what to order!!! i would also need to include a circuit to prevent deep-discharge & over-charge! This is where i need the main help: I cannot read electrical diagrams at all but try to but it takes a day of deciphering and thats only if i do it right, i have dyslexia and am fighting daily with it when it comes to referring to any diagrams concerning circuits so would it be possible if someone could draw the circuits i need onto an a4 piece of paper and photograph it to be posted here (or draw it in paint, lol) - what i mean is, to draw a basic 3 pin semiconductor (a square with the 3 pins coming out the bottom, lol) and then draw the wires that need to connect to all the 3 pins to then for the wires to go to whatever component they need to go to next, for example ? {the 'solder-fume-extractor's' wiring picture where you can clearly-see where all the wires connect to all the components is the only type of simple diagram i can read by myself} Still wiht me ? i lose myself sometimes! So as i understand it, from what ive been reading so far, as long as the voltage output of the battery pack is correct, say for example for my wireless camera, if ive used a semiconductor to get the voltage of my power-pack down to give an output of 8v rated to 500mAh, as the device (wireless camera) only uses a max of 200mAh, then does this mean that the device will only use what it needs and ignore the rest ? Also it has taken a week of help from many friends of mine to help write this question and to keep it on-track with my main goals for the 3 power-packs listed above! if anyone needs more info, please let me know and i shall endeavor to reply as soon as humanly possible, again many thanks for your help Again, many thanks in advance for all help given and i sincerely apologize the long speech of a few questions, im afraid i get too-specific when asking for help (and often branch-off far-too-much, like now, lol)

Topic by offtherails2010 

Please could anyone Confirm what i intend to do is Correct ???

Hello again ! Ok well, after another week of major research, i have a theoretical concept for my battery packs that i intend to create but would very-much-so appreciate it if anyone could confirm that what im about to do is correct in the sense that it will serve my purposes! Scenario: I Have a pinhole wireless Camera & Receiver, the camera will be attached to an RC 1/10th Scale Buggy and the receiver will be near me, in a bag, on the floor... Instructions that came with the gear states: The Camera should receive 8 volts DC and will consume up to 200mA per hour... The Receiver should receive 12 volts DC and will consume up to 500mA per Hour... (Yet the receiver runs off a 9v battery!) As i am still waiting for some battery holders & a few other components to arrive i have put together the following for prototyping, please could anyone confirm that this would  work as i intend it to ? : Li-ion Pack (For Wireless Camera): 14.4v { Four x 3.6v Cells } Connected in series Charging Start @ 13.2v Charging Finish @ 16.8v To Emit 8 Volts, 1A Max: i will Use an ''LM2940T'' Semiconductor i will want to Either BUILD (preferably) a charger OR Buy this CHARGER... -------------------------------------------------------------------------------------------------------------------------------------- Normal Battery Pack for Wireless Receiver: 24v { 16 x 1.2v Cells } -Individually charged- + FOUR x 4-AA Battery Holders (In Series) To Emit 12 Volts, 0.5mA Max: i will Use an '' L78M12CV'' Semiconductor -------------------------------------------------------------------------------------------------------------------------------------- The usage i currently get from a humble 9v battery connected to the camera and receiver (two 9v batteries in total) is WORSE than abysmal and i only get upto 15mins of decent record-time from the wireless gear so i will be making the two battery-packs above to get a much-longer run-time.... Questions: 1. Will my power-packs work as i intend to use them ? 2. When i go to build the Li-ion battery-pack i really want to include some circuitry for Deep-Discharge Prevention & Over-Charge Protection, could anyone please point me in the right direction for a schematic please ??? A MAJOR thank-You to all that have helped me in the past & A-MAJOR Thank-You in advance for everyone's help again!

Topic by offtherails2010 

Exactly what components do i need to charge a bank of our four (or however many it takes!) 18650 batteries {we will be using a dynamo} with an LED to show that the batteries are being charged ?

(if needed ?)Hello & Good day to you all, Me and a friend have plans to build a miniaturized 'Rolling Road' platform for our RC 1/10th scale nitro cars!! What we both agreed on is that the Rolling Road platform is to be made out of acrylic and using skateboard bearings and other hardware, but we are completely stuck, we have an idea to add lights to the platform, the kind of cold-cathode tube lights that are for inside-pc-use... We want the tube lights to run from a rechargeable battery bank from the Rolling Road but incorporate a charging system "built-in" to the platform and a system based on renewable energy because as our cars are nitro powered, they will be turning the rollers of the platform for many hundreds of thousands of times and we wanted to harness that mechanical energy to charge the battery bank - in turn to operate the tube lights! We are both ok the structural aspect of building this rolling road platform but dont know where to start on fabricating an electronic set of components culminating into a sustaining system that produces (almost) free energy! The system must be able to run 4 sets of these tube lights, each tube light set is comprised of 2 tube lights each, so 8 tube lights in total ! The tube lights are rated at 12 volts. What our dreams are : (lol) - The system must collect the electric being made to charge a battery bank, - The system must have an LED 1 to only show the battery bank bank is being charged, - The system must have an LED 2 to show that the battery bank is fully charged, - ALSO ! if at all possible, include a simple row of 6 or 7 LED's (LED BANK?) to indicate how full/empty the battery-bank is & - Lastly, there must be a switch to switch off the circuit that charges the battery bank (when batteries are fully charged !) Ingredients: (what we DO have, lol) 20 x 18650 batteries Plenty of spare motors Lots of different grades of wire soldering skills a few switches 10 Pairs of 12v PC Tube lights (Both 4" & 12" ) Small to medium range of "ON Semiconductors" (Voltage Regulators) Max Input Voltage is 40v of one of these! What we dont have: - Knowledge of electronics! - LED's - Capacitors (if needed ?) - Resistors (if needed ?) - Transistors (if needed ?) - Semiconductors (if needed ?) - Diodes (if needed ?) - Help ! Please please please could anyone help us to even roughly 'sketch' a set of components that we could solder together, lol, a Circuit, lol x2!, so we can start ordering the needed items to enable us to make this miracle happen ?!!? But to make it idiot-proof (dumb-it-right-down for us!) and extremely simple circuit diagram, not the actual way you geniuses write em, if say to draw a semiconductor, i would draw a square then draw 3 lines coming out the bottom of it to show the legs of it! We were only-just able to follow the circuit diagram HERE - ONLY BECAUSE there was a picture of exactly how the circuit looked, in-real-life! So we followed the wires exactly to make the solder fume extractor but were only able to, again, because of the pics! please help! i feel like crying! lol ! We have both spent a few years trying to read electrical diagrams and we get lost very easily ! Is there even a way to dumb it down for us ??? Is there any hope ?!!?  lol A very-Many thanks in advance to all for reading this and even more for any help received !!!!

Topic by offtherails2010   |  last reply

Find the average and highest voltage from multiple photodiodes before analogue Arduino input? Answered

Hi, I have a large number of photodiodes (too many to connect all of them individually to the analogue inputs on my Arduino) so I was hoping I could form say 4 groups each containing several parallel photodiodes and find the average the highest voltage for each group. This way each group uses 2 analogue inputs. The picture below depicts one group of photodiodes connected to two 'black boxes'. The 'highest voltage' black box would determine which input had the highest voltage and would then output that voltage to the Arduino. The 'average voltage' black box would average the input voltages and output this voltage to the Arduino. I have found a passive averager circuit on this website - - which appears to be suitable however I have no idea how to find and output the highest voltage. Hopefully this sufficiently explains what I'm looking to do and I look forward to getting feedback. Andrew

Question by Andycb93   |  last reply

I have a LED i cant light, no matter what. It has a little black dot in it. What kind of LED is that? Answered

Appearance: It is a common 5mm, transparent case, LED, being different from all others only by having this very tiny square dot over its anvil, kind of covering the reflexive cavity where the semiconductor (i don't know which) gets lit up. Other: I could not light this LED whit voltages from 1.5V to 3.5V. =O It came out of a photocopying machine, and was paired with an IR LED in some kind of emitter-receiver set. Other components of this set were a pair of smd resistors and a smd trim pot. Would it be and IR receiver or photodiode? UPDATE: I've took some photos of the mysterious LED. BUT, as no macro-enabled camera was available, i had to do the ghetto-way of photography. Soo: i have photos of it compared to the IR LED, and some photos of both anvils (IR, unknown), at 200x magnifying. Here they are. BTW, i hadn't tested the suggested circuits yet. =(

Question by vinacarv   |  last reply

How do I tune this?

I bought a passive subwoofer crossover the other day in Toronto at some crazy combination Home Hardware/Chinese ran semiconductor supply shop. It was simply bought as a pcb in a bag for $18, which I thought was a good deal for that much so I picked it up. It has a large inductor coil and a 188uF 50V capacitor mounted on it, along with a positive and negative terminal soldered on for input/output mono speaker connections. I did hook it up to try in line with my sony stereo and turned the default button on my EQ on to restore the original signal and it worked pretty good to block out most of the signals like I was looking for it to do. However even with the boost on my EQ at 30 and 60 hz, it's not coming through to my sub even like before I hooked the crossover up. I was wondering if that's because of the capacitor or not? The little peice of paper that came with it said it was a 120 hz passive crossover and that it was workable with 4 or 8 ohms. I'll post pics tommorow when I wake up as it is lateeeee. I appreciate if anyone can help me as I don't wanna take the capacitor off there to find out that it wasn't worth it.

Topic by Punkguyta 

Anyone have any interest or experience with proximity based BLE iBeacons/Sensors?

Hi All, I'm semi-tech. & new to the community but figured I'd reach out, so please bear with me as I describe the following ask.Since last yr. I've been on the hunt for a small iOT sensor that based upon close proximity can be identified & actived via BLE without an attached app. Thought an Eddystone may work but purchased a few nRF51822 semiconductors but haven't tested them as yet & not sure if it's even the proper solution. I would need to program this beacon/sensor to launch a website, video on nearby cellphones. NFC works perfect but is extremely limited to only a 5cm range & requires an NFC capable device.I was told to try: "Perhaps the Raspberry Pi 3 Model B+ could work since it supports BLE and also has WiFi: "But I'll need something much smaller [see attached] & less costly per unit. I'm envisioning something no larger than a quarter & powered possibly by a watch battery. Do you think the nrf would suffice?Any suggestions I'm super open as well as just ideation. Thx in advance.

Topic by AxelFoley77 

Trying to identify a few old electronic parts

I inherited several cabinets full of electronic components from a friend's dad who used to work at Apple during the Apple ][ days and although I've identified most of the parts, I needed some help identifying some old Fairchild parts in "plastic can" type packages, and some other miscellaneous parts. One is labeled "F" (Fairchild logo, I think) μL 91428-750, and has eight leads from a round ceramic plastic-topped package. The only thing I can find in google that American Semiconductor sells it as a "Fixed Positive Voltage Regulator" (but I don't have any assurance this is the same part) but doesn't seem to have a pinout or datasheet: . I've got probably 50 of them, so I'd really like to find out what they are. Another similar 8-lead round ceramic/plastic can part is labeled "F" μL 90028-807 (and a couple marked 90028-639, is that a date code, 1963?!). Can't find them anywhere on the web at all. A couple more 1-off chips that I can't seem to find anywhere are labeled: SCM90058C "M" (Motorola) 8002 (16-pin ceramic DIP) DTμL93059 "F" (Fairchild) 839 (14-pin ceramic DIP) Any help you could provide identifying these parts would be greatly appreciated! Andrew

Topic by andrew.allen.75839 

How can I determine if my LM386N amplifier chip is defective?

I'm following the National Semiconductor datasheet for an approximate 200X gain (very minor modifications), but I get no gain at all. I do get sound though, which makes me believe the chip may be working just fine. The reason I know I have no gain is if I hook the audio out directly into the speaker I get the same sound volume/quality. I'm using a 9V battery for power, a 10 microfarad capacitor to connect pins 1 and 8, and a 220 microfarad capacitor between the 5 pin and the speaker positive input. Here are some differences in the modification: 1.) I'm using a 4 Ohm speaker and not an 8 Ohm speaker, but from what I understand that shouldn't matter since this is just a matter of less resistance and not more. 2.) I don't have a bypass or a .05 microfarad coming out from pin 5. 3.) I'm using a standard RCA cable from my computer headphone jack to test, and clipping a 20 gauge wire to each to run into the breadboard. I'm really new to all this, and I've tried like 3 or 4 different configurations, but they all generate the same sound volume/quality. Any suggestions would be greatly appreciated.

Question by giantjamsandwich   |  last reply

How to select transistor?

Hi guys! How do you know which version of transistor to select when it comes to doing some projects? I mean, lets say i have all the parameters of my project, the output current and voltage, so how do you know which specific model of transistor to select from the data you have? Is there some kind of list from which we can select the required model from our data? For example, i have an LED array which draws about 90mA of current in total and has a total operating voltage of 15V, and from past instructables that i read on this site, i know that BC547 has a current rating of 100mA and can tolerate the voltages, so i can use it. My question is, that suppose i didn't read these instructables, then how will i know which transistor or FET i have to select that has a current rating of about 100mA and can tolerate the voltages(i.e how will i know that i can select the BC547 or alternative)? Also, when selecting a diode for example, i know from reading few instructables that 1n4007 has a rating of about 1A and can tolerate good amount of voltages. Suppose i don't know about the diode, then how will i know that based on my requirements, i can select the 1n4007 diode? This is an example in general, and it applies to all cases of load currents and voltages, and other semiconductor devices.

Topic by charmquark   |  last reply


LED throwies are so populear that this happend. i serched for LED on google. Light-emitting diode - Wikipedia, the free encyclopediaA light-emitting diode (LED) /ɛl.i.ˈdiː/ [1] is a semiconductor diode that emits incoherent narrow-spectrum light when electrically biased in the forward ... - 153k - Cached - Similar pages - Note this Howstuffworks "How Light Emitting Diodes Work"Light emitting diodes form the numbers on digital clocks, send data from remote controls and light up traffic signals. Find out how LEDs work. - 62k - Cached - Similar pages - Note this SUPER BRIGHT LEDS homeOffer LED products and components including replacement bulbs and circuit boards. Includes detailed specifications and wholesale information. - 4k - Cached - Similar pages - Note this is everything LED. Find loose LEDs, LED controls ...TheLEDLight.Com stocks a variety of low voltage (12vdc or 24vdc) LED lighting products such as under cabinet lighting, LED bulbs, LED fixtures, ... - 40k - Cached - Similar pages - Note this LED Circuitry tutorial: how to hook up LEDs.LED Circuitry tutorial: how to hook up LEDs. Text and illustrated instructions for setting up a circuit, what is series and parallel circuits, ... - 15k - Cached - Similar pages - Note this LEDs Magazine - LED Technology, Solid State Lighting and other LED ...LEDs Magazine - LED Technology, Solid State Lighting and other LED Applications. - 31k - Cached - Similar pages - Note this What is a Light Emitting Diode?What is a Light Emitting Diode Fundamentals of Physical Science Experiments by Experimentation ACEPT. - 8k - Cached - Similar pages - Note this LED Throwies - Instructables - DIY, How To, art, techDeveloped by the Graffiti Research Lab a division of the Eyebeam R&D OpenLab, LED Throwies are an inexpensive way to add color to any ferromagneti... - 178k - Cached - Similar pages - Note this

Topic by dsman195276   |  last reply

Crystal radio help anyone?

(If you want the blow-by-blow of my questions, skip the following gigantic piece of text and proceed to the 2nd list after the first)   I was reconsidering making a crystal radio the past week and so I set out to research the topic on the 2nd most popular information database on the internet which comes out of the 1st most popular one. According to wikipedia, all you need is one diode in order to split the AC signal coming in via the antenna in half, therefore it uses half-wave rectification (it's not quoted; it's what I understand from it). Could full-wave rectification be also used? Like connecting the antenna to a bridge rectifier (aka. diode bridge, aka. 4 diodes stuck together)? I know that half-wave rectification yields pulsed DC, but I also don't understand how. By that I mean what happens to the other half? Does the other half of the wave connect directly to the output? One last thing, I know the largest metallic object I can ever use as an antenna is basically just my roof, but then I don't like coming up to the roof and looking for some exposed metal to connect to. Any thoughts on what huge, metallic items I can use in my household? I've already thought up a list of what I could use for an antenna: -Window screens -Extremely long piece of wire (I have an 8 meter long CAT5 cable going from the 1st to the 2nd floor) -My front gate -Sheet metal laying outside my front door (not the gate) Here is the summary of all my questions: -Is this wikipedia article true? (see at the list "semiconductor" area) -Can full-wave rectification be used on such radios? -In the case of half-wave rectification, where does the other half of the signal go? -What can I use as an antenna (excluding my roof)? Aside from the asked questions: -Is there any other way to tune to a particular frequency? -I'm asking opinions to people who know what they're doing (no offense to beehard44, this is more of a poll that anything else).

Question by nutsandbolts_64   |  last reply

High power LED Ledengin 10W. How can I drive 4+1 of these from a laptop power supply?

Dear fellow hobbyists, I have four deep red, 10 watts Ledengin bulbs mounted on a MCPCB (as well as one cool white 10 watts bulb from the same company). I would like to bring them to life using a laptop power supply. I know that I do absolutely need a constant current to avoid getting SEDs or friods. Unfortunately my knowledge of circuits is very basic and several decades old. I have read and re-read several times the excellent instructubles tutorials and gathered more information from the web. I think I got it (well…sort of) and I have successful built a small array of inexpensive, low power (20 mA) LEDs, using a resistor as the current limiting device. However I am aware that this is a rather inefficient way to feed high power LEDs, particularly related to power dissipation (i.e. efficiency of the circuit). I would like to build a LED driver using either 1) the NFET + NPN circuit #2 from Dan ( but I am not sure if the listed components are good enough to drive four/five 10W LEDs (mid power LEDs are used in the example), or 2) find a buck pack that does not cost a fortune and is guaranteed to work (National semiconductors seems to have a few at very low prices, such as …., but I am not sure they will do the job and how well) . Also, I would like to know if it is possible to drive the 4 red together with the 1 white LED from the same power supply, or if it is better to use two PS, each with its own driver? The two ledengin LEDs are LZ4-00R210 for the red and LZ4-00CW10 for the white bulb. I intend to drive them at 700 mA to maximize shelf life and the maximum Vf for this current are 13.76 V for the red (only one bin code) and 16.64 V for the white (for safety I was advised to use the highest Vf bin value from the datasheet as it is close to impossible to get the correct bin code specific for the bulb from the distributor). I am actually considering running the 4 red + 1 cool white LEDs all in parallel, with each individual LED having its own current limiting device (the inexpensive ones from Dan): a bit more involved but maybe the safest?Thank you in advance for all the help you can give me.Arcibaldo

Question by arcibaldo   |  last reply

Easy automated method to find chronological age of an integrated circuit design? Answered

This is not a question related to a homework or career assignment. This question is an existential question. Specifically, the thing that I am wondering if it exists, or not, is an easy and automated method for finding the chronological date, e.g. a year, Anno Domini (AD) or Common Era (CE), when a named integrated circuit (IC) was introduced.  Preferably this method exists in the form of a free resource on the Web. As an example, the well known 555 timer IC was introduced in the year 1971, and I am reasonably confident that was the year, because the Wikipedia article titled "555 timer IC", contains the words: "Introduced in 1971 by American company Signetics, the 555 is still in widespread use..." And I assume that statement is totally true, because if I can't trust the people who edit Wikipedia, I mean, who can I trust? ;-) Unfortunately, Wikipedia does not have a fact-filled article for almost every IC every sold.  In contrast, a place like has data sheets for almost every IC ever sold, but, it turns out, the data sheet does not always reveal the year the IC was introduced. To clarify this further, the thing I really want to exist, would be like a web site, with a name like:, or, or etc. (Please note that none of those URLs point to actual existing web sites, at the time of this writing.) Moreover, I am fantasizing this web site would contain a form, for to enter the name of the IC to look up, and then after hitting the "Submit" button, it would magically tell me what year that IC was introduced to the world, and maybe also which semiconductor company gave birth to it. As some example input and output, the query NE555 would return:  NE555, 1971, Signetics(r) As an additional twist to this fantasy, the query, LM555, would return the same thing, and this magical web page would like, know, that LM555 was a later version of the same IC, except produced by a different manufacturer, namely National(r); i.e LM555 was National's version of the 555 timer . If you have read this far, I congratulate you!  And I appreciate your eyeball time! If you are wondering about my motivation for this question, it is just that think the year an IC was introduced would be a very useful metric, like for answering more specific questions, like: The SG3524 and LTC3780 are ICs used for making switchmode power supplies.  Which of these ICs is more modern? I.e which IC was introduced latest? It turns out, the answer to this question is: The SG3524 is older (introduced first).  The LTC3780 is younger (introduced second). The SG3524 was introduced (I am guessing) in 1977, and that guess is based on some cryptic scribbles in a data sheet for the SG3524, published by Texas Instruments(r). The exact characters were: "SLVS077D – APRIL 1977 – REVISED FEBRUARY 2003" and I am just naively interpreting that blurb to mean the SG3524 was introduced in 1977. Regarding the LTC3780, I think it was introduced some time in the 1990s.  Looking at its datasheet, from Linear Technology(r), I could not find an obvious description of what year it was first introduced, but the first page mentions some US Patent numbers, and looking up those patent numbers, gives dates circa the early 1990s. So the LTC3780 is the younger than the SG3524. However to find that answer, I kind of had to do a bunch of reading of datasheets, and US Patent numbers, and that method took a little bit of work. My question:  Is there an easier way to find out how old (or young) an IC is?  More specifically is there an existing resource on the Web, like a free database, or a IC history site, or something where I can essentially "look up" the year an IC was introduced. By the way there is no absolutely zero urgency attached to this question.  So please answer if you feel like it,  and don't if you don't. I thank you for reading this.  My name is Jack A Lopez, and I approve of this message.

Question by Jack A Lopez   |  last reply