PN Junction Diode Thermoelectric Generator?

Hi, I was wondering if you could DIY a thermoelectric generator by dissecting  some PN junction diodes and sandwiching the P type material adjacent to the N type materials between heat conductive material, such as two circuit board wafers?

Question by jmlidea 6 years ago  |  last reply 6 years ago

How do solar junction boxes work?

With solar systems, you often see a junction box that apparently is necessary equipment for a solar installation. What is it? It has diodes inside, right? Why do you need it?

Question by Udon 8 years ago  |  last reply 8 years ago

help with installing a doorbell transformer?

I just bought a doorbell transformer and i know how to do everything but install the transformer.. i know it could be hooked up to a junction box i just dont know how. it has three wires on the back, and a junction box i looked at had four different colors of wires in it. i do not know how to install it. please help me.. thanks

Question by 87bhoward 8 years ago  |  last reply 8 years ago

Landscape Lighting Electrical Connections?

We are in a newest home (5 years old). We had in-ground wiring installed but no lights. My wife now wants landscape lighting installed.I have two sets of 12 awg wire terminating near an outlet at the rear of the house. One wire was tapped with black electrical tape while the second 12 awg wire had green electrical tape.I found all the wire loops (where they come out of ground)However, I also found a junction box. There are two sets of 12 awg wire into the junction box but nothing is connected (pic attached)I then found a location where two sets of wire terminate. (Pics attached) comes out of ground, does a loop, but there's also an end piece. First I assumed, I had a "loop" system" but the junction box and now these two locations with en end piece of wire is throwing me off. Thoughts? Any suggestions would be helpful.ThanksB

Topic by BertF8 1 year ago

Can any one let me find a substitute of BT33F ?

Can any one let me find a substitute of BT33F ? its a single junction transistor i have tried 2n2546, 2n2067, 2n2068 but could not get sucess, pls any one help me out.

Question by raphelcf 1 year ago  |  last reply 1 year ago

Anybody working on cryolipolysis? Answered

I am looking at using a pair of Peltier panels to make a "spot reducer" using cryolipolysis. Cryolipolysis is what the Zeltiq machine uses to freeze fat cells such that they dissolve. On a bodybuilding forum they were talking about using cool-paks, those gel-filled plastic blocks that you put in the freezer.  My idea is to take a hand clamp and mount the Peltiers to it. I may need cooling on the hot sides, for that I will probably use liquid cooling blocks from computer CPU coolers. Then, you just clamp those babies on your love handles and crank up the juice. "Animal studies show a fat-reducing effect starting at around minus 1C, with the plate in place from five to 20 minutes." Since Peltiers get about 65 degrees C in differential, and room temp is about 26 degrees (warm room!) it will be a piece of cake for the junction to chill off those love handles. Would not be hard to put a temp controller on it to protect from frostbite or from burning up the junctions. Before you scoff, a Zeltiq treatment runs $700!

Question by Exocetid 8 years ago  |  last reply 8 months ago

BJT under saturation condition??

Under saturation condition base current is very large that voltage across Base-emitter junction of  silicon based BJT is more than 0.7 volt. In this condition the voltage at collector (Vc) is 0.2 volt. By kirchoff's voltage law Vc=Vce( imagine emitter is directly grounded) Vce =Vcb+Vbe. If Vbe>0.7volt how Vce=0.2volt? As Vce includes Vbe, it must also be more than 0.7 volt. But it is 0.2 volt wich is less that 0.7 volt. How?

Question by deepakmurali 7 years ago  |  last reply 7 years ago

For FET of n-chanel Idss current is maximum but i found it to be as minimum? Answered

For FET in n-chanel i found that as i incresses the Vds of transistor  the depletion layer of the both pn junction increases .due to this less no. of electron crosses the channel.when both the depletion layer touches each other then Idd current will flow which is maximum possible current through the drain which is approximately equal to zero mA.but as tge depletion layer touches each other there pass very few electron .so as the less number of electron pass current must be minimum instead of maximum  

Question by vivekbittu77 8 years ago  |  last reply 8 years ago

Logic Gate Help Needed Answered

I am building a Binary to Decimal converter and i need help making a flawless AND gate from bipolar-junction transistors. If someone could Send me a link or email me some schematics, I would greatly appreciate it. If you do email the schematics please make sure they are compatible with Eagle. I don't want to use a converter chip because it takes away the fun of the project for me. I have tried all of the common types of AND gate configurations using NPN's (C-fwd B-in E-collect, C-in B-fwd E-Base, Etc.).

Question by toast5678 6 years ago  |  last reply 6 years ago

high output metal to metal thermoelectric generator?

I saw this on youtube: He has like 16 wires in this setup, and it generates enough power to light an LED... how much power could you get with some more wires? Say 1600? Does the thickness of the wire matter? Sorry to make you watch the youtube video, if you don't want to, here's what's going on. This guy, Nyle, uses copper wire lengths which he has heated at one end and cooled to coat each end of each length with copper oxide. He then bends the wire so that two ends of copper oxide-coated wire are touching and another end is about 3 inches from the junction. By heating the loose end, and touching one wire to another, he's able to generate enough current to light an LED... pretty neat!

Question by jmlidea 6 years ago  |  last reply 6 years ago

How would this schematic look on a circuit board?

I currently have this schematic for solar powering my Arduino board. I got this schematic directly off the instructable:   I am a newbie to this kind of stuff and understand how circuit boards work but have spent hours trying to figure out how to correctly draw it like it was on a circuit board. I made a final attempt and drew it on a PCB circuit board template shown below. The components used are annotate with their polarity (the switch isn't cause it can go either way) and the red lines indicate the soldered connection. If someone could just check it out and make sure all the parts are right, it would be greatly appreciated. The main problem I have with it is the junction where the battery positive, switch and Arduino positive all meet. All help is greatly appreciated Thank you, Connor

Question by cobrien2115 4 years ago  |  last reply 4 years ago

mA on high intensity LED?

I bought a couple of red "Coast LED Lenser" LEDs from Frys ( They are in the standard 5mm package, but they give no forward voltage and the mA looks a bit high, being without a heatsink . If anyone can tell me if it looks correct and not a misprint, i would be very grateful, since coast doesn't have them on their website anymore. Oh yeah, while trying to light one I ran 8.5V@4.5A (PS2 adapter) accidentally (forgot the resistor) and it exploded loud pop instead of melting or burning out the junction like the 3mm LEDs from ebay, if that helps. The specs.   Intensity :                       10,000 mcd   Directivity:                      15* (degrees)   Operating Lifetime:      Up to 100,000 Hours   Wavelength:                  620nm   IF30:                               mA   IFP:                                 100 mA   VR:                                  5V   PD:                                  120 mW   Topr.:                              -30* to +100* (degrees) I'm guessing the forward voltage would be about 2.00V +/- .20V

Question by LuciferTengu 9 years ago  |  last reply 9 years ago

Need an 8 foot super rigid tube that needs to beak down into 2 foot sections

Hi -- I need to create a tube that is as small diameter as reasonable, relatively lightweight, and very stiff. It will be supported only on the extreme ends (thus the need for stiffness). There will be a comparatively light load, equally distributed over the entire length of the tube when in use.  The thing needs to build up to 8' overall, HOWEVER, no single section can be longer than ~2' when broken down. My first thought was 1" PVC - it's NEARLY stiff enough, but a trifle bulky, and it does droop in the center by about 1.5". 3/4 EMT tube is great, and stiff over a 10' span (when in one piece). Problem is how to connect the sections together. Typical off-the-shelf EMT junctions tend sag just trying to support the tube with no load. I have a number of ideas that are likely overly complex and stupid, but was wondering if y'all might have a something that I have not thought about. Thanks! Ted

Topic by morgan834 1 year ago  |  last reply 1 year ago

What do you recommend for wire connectors / clamps for making a Nitinol shape-setting fixture?

I'm weaving Nitinol wire so I have a square piece of plywood with the shape that I'm weaving around placed in the center and the bundle of .7mm Nitinol wire is emanating also from the center.  For clamps I used speaker posts that have hand-rotatable post "screw-collars" and are gold-plated.  However they're really hard to work with and to mount.  They're great because they also have a high-current screw-in wire junction in the back.   Anyway, what alternatives can you think of while requiring a hand-turnable release and clamp of the Nitinol wires (so plain terminal blocks won't work unless you also found a screw with a handle that fits).  There will be about 20-100 small wires used in the bundle to weave the shape.  And the board is about 30cm sq. at the moment so more likely there will be only 20, in order to fit the wire clamps unless you know of a micro method, such as: copper tubes and "nails", which might work now that I think of it...

Question by daniel.donnelly.549 4 years ago  |  last reply 4 years ago

Cyclist attacks again...

Uh this is annoying after last year when there were attacks on cyclists made by motorists I've been thinking it better not happen again this year, well my fears turn out to be well founded, just as our bike month kicks off so does the war on cyclists...Coming down the hill towards work, going well over the posted speed limit of 30mph a boy racer in a vauxhall corsa boxed me in and tried to run me in to parked cars, i managed to get in front of him and out from behind the parked cars, he then went on the wrong side of the road and overtook me, only to try and brake check me, I was absolutely incensed he was looking me right in the eye through the rear view mirror, He got away at the junction at the bottom of the hill because the light was green and he was going straight on, I was going to take out his wingmirror but nay he didn't stop, next time I see the car I'll get his liscence plate numbers, then report his car as stolen... because he'd get off scott free for attacking me like that, despite having endangered my life and broken the speed limit by a lot more than I did...

Topic by killerjackalope 11 years ago  |  last reply 10 years ago

Thermocouple calibration - How to

Hello,I have a few questions about the thermocouple calibration.I want to use three type R thermocouples to measure the temperature during a 3d printing process using an Arduino Uno and the max31856 amplifiers. Right now I am doing tests with K type thermocouples before we buy the R-types. It seems to work fine, it measures a room temperature of 22ºC more or less and reacts reasonably in my opinion but I would like to know if the measured temperature is the actual temperature.1. Is a calibration needed? I know the amplifiers (max31856) do some corrections automatically, but maybe an extra calibration is needed.2. If such a calibration was needed, how would I do it? For example, I will put copper in an oven and heat it and measure the temperature with my thermocouples and with a bolometer. If my thermocouples measure something different, how do I correct it? Theoretically my program transforms (via amplifiers) the measured tension difference into temperature, correcting it at the junction. How would I tell it now that it has to measure differently?3. If no calibration is needed and, as I explained in 2, my thermocouples measure something different as the bolometer, which one is the accurate? Thank you very much for your help.

Question by DiegoH57 1 year ago  |  last reply 1 year ago


Hi there, I would like to say hi to the instructables members for a start. Hi! I have always enjoyed reading from this site and I see that there is a lot of help in the topics posted here. I am a Computer Technician that now wants to play in the hardware game (Are you all enjoying Windows 10?). So I'm starting small with an arduino and the raspberry pi, (not side by side yet,) a few motors, servo's, 7" color crystal display, and other things that I have salvaged from stuff or found cheap. I have a few of these CD drive eject motors with lil' knobs I was reading this post about how to make an electric magnet as I am trying to manually make my own point motor for my model train set.  For those in and not in the know, here is some information about what I am trying to do. Create 2 electric magnet coils that pull or repel a nail or metal bar where an upright pin ~2-4 mm is able to travel a distance of ~6-8mm (oo Gauge) in order to change a track piece from one position of a "junction point" to the other, allowing the train to change track or take another route. I would like to try and do this myself as I have plenty of different types of gauge wire, dpdt's (for pole switch?), nails or metal bars(to act as middle pin maybe and bar to be pulled back and forth), diodes (for bridge rectifier) , resistors (to calm the voltage down if I have to as I think it will get rather warm else), a constant power supply (16V ac admittedly)  and plenty of BABY BABY small yet rather strong.. magnets..etc.. ( BTW These were taken from a motor that was inside some water speakers, for perfect reasons the motor had a spin disc attached to it with 3 very small magnets, then in the water compartment there is a spin disc with more magnets attached and a wirly-gig to create the siphon to jettison the water up when the music is played so I now own 60 of the little blighters, (that's if i need them at all to be honest I'm a little lost in this idea))  So please take me as a n00b and please help me in going about this. Yes I could go buy one, but what does that achieve, when I believe I have everything I need at my fingertips and I wish to learn. I presume I will need to deal with the constant AC in order to be able to make a switch to change the polarity of the two coils in order to pull or repel the magnet or nail in either direction to then move the tracks junction from one line to another. I'm going to try and make some coils, in some rather thin wire that is insulated.  Thanks again for any replies. EOL

Question by WAREZRONIN 3 years ago  |  last reply 3 years ago

Outdoor listening installations

Would appreciate some advice on this project.  I'm putting together a proposal for a series of outdoor sound installations in a nature park.  a couple of the installations will be places where you can plug in headphones to listen to certain sounds captured live from a microphone in an interesting place- for example a hydrophone in a pond.  The plan is that the mic will be hooked up to 3.5 jack sockets and listerners will be able to plug in their own headphones.  Now obviously there needs to be some amplification because the mic signal level will be far too quiet to hear on headphones. I need a power amp that will be powered through a solar panel.  My question is, shall I just use a headphone amp, like the Behringer ha400 or make my own power amp circuit? I need to be able to make everything sturdy and fit into a weather proof junction box to protect it from the elements. I have done some experiments with an LM386 power amp module but there was so much background noise and it didn't pick up the mic level at all (may have been a problem with the mic I was using,it was a crappy little lapel mic.- I did get a signal from a piezo disc but it was again really crackly and noisy.)  If it is best to build a circuit with a power amp module, could people make suggestions of ones that will sound good and clean, and work with stereo headphones.  Thanks a lot Ash

Topic by AshtonM4 3 years ago  |  last reply 3 years ago

Homemade Cryolipolysis revisited - is cool plate and vaccum technology instead of ice packs more reliable?

Http:// Using the Peltier effect via an aluminum plate, would it be possible to create a homemade cryolipolysis machine? The method cryolipolysis uses to kill fat cells is this: The vacuum pulls the adipose tissue away from the body's core along with the surrounding skin folds to prevent the tissue from being warmed by body temperature. The temperature of the fat cells drops to between -1 degree Celsius and -10 degrees Celsius, triggering pre-programmed cell death. After one hour of application all of the susceptible cells in the area have been triggered and will die off between two weeks and 3 months later. I don't want to use something as inaccurate as ice packs, I would like to buy an aluminum plate, attach wiring to one side to utilize the Peltier effect, apply a light vacuum to keep contact, and insert some kind of temperature control per Peltier junction to keep the temperature in the optimum zone. As far as the back of the connections that gets hot, cooling that with circulated anti-freeze or water should be sufficient, but I'm not sure of the best configuration on the plate/vacuum setup. The way the current Zeltiq technology pulls the skin so far away from the body leads me to believe it's not great for any area that doesn't have a lot of excess skin to pull on and I would like to create a shallower cavity that can fit in harder to reach places like the side of the chest under the arm.

Question by DIY_Novice 6 years ago  |  last reply 2 years ago

Is it possible to drive a tip31 from the signal generated from an mp3 player? Answered

I have been reading through the many many instructables about driving leds from an audio signal, but so far my experiments  have not worked out.  I'm trying to drive one led from the audio signal coming from a pair of earbud style headphones. Here are some videos demonstrating the circuit. (I can't get the editor to embed videos today, so please follow the links to view the youtube videos Proof that the led works Proof that the transistor works Hooking up the audio signal - I got nothin Proof that there is an audio signal coming into the circuit I'm basing this circuit on the numerous diagrams on instructables for syncing an led to music.  Here are just a couple of them... Sync LED to music LED Music Sync Headphones These and many other instructables show the same circuit and they all seem to be working, so what am I doing wrong? I hooked the base of the transistor up to the signal coming from one half of a earbud type headphone wire, hooked the ground of said wire to the emitter, and then hooked up the collector/emitter to a circuit with one standard led and 3V worth of batteries.  I checked the output of the headphone wire with an oscilloscope, and there is definitely audio coming out of it, but it's a very tiny signal, on the order of a few millivolts.  How does such a small audio signal generate enough sound to be heard?  How does anybody drive a transistor off such a tiny signal?   Doesn't it need at leat 0.7 volts to get over the diodey hump of the base-emitter junction. ( I don't know, that was a pidooma, it's been way too long since my last electronics class. ) thanks for any thoughts...

Question by foobear 8 years ago  |  last reply 8 years ago

Having a peculiar issue with the max6675 and grounds?

So first off, this is an application for use in a car. I have ensured that all of my grounds are good, and the power is clean, so I know these are not the issue, at least not on the car side of things. I am trying to get an electric fan controlled by an atmega328 (through a relay), which I have successfully achieved  on bench tests using an alternative heat source. It works reliably until I apply the circuit in the car. When I install it in the car with my thermocouple on the radiator pipe for the temperature reference I get all sorts of temperatures that are not the correct one. Its either very high, or very low. I have tried multiple thermocouples (of similar style) with no changes. If my thermocouple is not making contact with any grounded portion of the car (for example, the engine) it reads fine, so I know that my issue lies somewhere in there. An easy solution would be to simply mount the sensor in a coupler in the radiator hose (thus isolating it as best as I can) but I would rather fix the issue than apply a bandaid. I've tried searching for other people having a similar issue but haven't had any luck. One peculiar thing to note is that if I have the ground disconnected, and the thermocouple touching a ground, the system receives power, so I am assuming that the junction makes contact with the outer case of the thermocouple. My circuit is nothing too elaborate (I can upload a schematic if need be); I have a DC/DC adjustable converter to get 5v for the micro and 6675 power, which does not have an isolated ground, an atmega328, an OLED display, some tact buttons, and a max6675 development board. There are other passives as well but those should be minor. Does anyone have any idea what may be going on with this? I'm stumped. I should be able to provide any info you may need.  PS: this is the development board and thermocouple that I am using: 

Question by zack247 3 years ago  |  last reply 3 years ago

Are you guys up for a challenge, I need a hand with something

Well, peeps, I got a challenge you guys are going to help me with. Let me explain what it's about. We pay $35 something a month for 3mbit internet. I've only ever seen 1.3-1.5mb of it. The CO (Centeral office, it's a brick building they place in each "area" and it handles all the telephone and internet connections for you area, most isp's have one or more in each town they cover and those buildings are linked with fibre optic cables) is just down my street, I can practically walk out my front door, down the street and see it. So I'm rather close, and to top that, tiverton (where I live) is where my isp decided to set home, the "HQ" is just a km down the road from my CO building. Logic tells me that I should and have the right to get all of that 3mb I pay for, I can see if I live a certain distance away, but I don't. Here's where it get's a bit interesting, I was suggested to by dijital101 to run some cat-5 cable between the junction box and my dsl modem. Well that's just what I did today, I bundled the 8 seperate wires into two big wires (4 each) and even soldered them to ensure a good connection. Ran the wire, connected it all, attached a phone plug onto the other end of the ethernet cable and got it all hooked up. Well wouldn't you know, I see not one bit of differnce. Speed tests still show like 1.2-1.5mb (When It starts, it takes forever to even build up speed). But Interestingly enough...I get full upload speed (512k is what I get for up). When I'm uploading something too, such as files or torrents, if I let it go the full 70kb/s it limits my download speed to 30kb/s around there. This is something I've had to put up with for a long time, if anyone is familiar with "BMTS" that's my isp. My question is, what is there I can do to fix it? I even unhooked the wire coming off the telephone pole, cut the ends off and re-stripped the wires and that did nothing either. The wires are pretty old and tarnished, even under the rubber coating, and they're kinda peeling too. Should I call my isp up and complain again, think they'd come and replace the line? I just don't know what to do, if I can fix it, I'm going to cable internet.

Topic by Punkguyta 11 years ago  |  last reply 11 years ago

Escape from Berkeley (by any non-petroleum means necessary)

Now that Convert your Honda Accord to run on trash has won the Craftsman Workshop of the Future Contest, it's prepped to race to Mexico for a chance of winning $10,000.00!Our friends at The Shipyard and ALL Power Labs are running Escape from Berkeley (by any non-petroleum means necessary), the premier alternative-fuels road rally, for the second year in a row. Last year they escaped from Berkeley and fled to Vegas; this year they're running for the boarder.The directions are laid out for you, all you need to do is get to work. Will you be there? If so, be sure to document your alternative fuel project on Instructables!A road race to Mexico, no fuel allowed.June 12-16, 2009Berkeley, CA - "Escape from Berkeley (by any non petroleum means necessary)" is a road rally of alternatively powered vehicles from Berkeley, California to the US-Mexican Border. Part engineering problem, part artistic opportunity, the rally challenges contestants to start their "engines" on something other than petroleum based fuel, and by any means necessary, cause their "vehicles" show up at the border five days later - using only fuels/power/motive force scavenged for free along the route.Last years inaugural race took us from the DIY oasis of ALL Power Labs in Berkeley, CA, to the consumptive excess of Las Vegas, Nevada. Returning to compete for the second running of the race will be 1st Place Rally Winner Jack McCornack from Cave Junction, OR and Runner Up Wayne Keith from Springfield, AL. Registration for new racers is now open. Interested racers should write types of vehicles are welcome. All schemes for non-petroleum based transport are encouraged. In short, everything is permitted - just as long as your "fuel" is from a non-petroleum based source, your acquisition of it does not require money, and you start the race with no more than 10kwh of it on board. The full field of power generation and conversion is open for scavenging and creative power hacking.DARPA had a Grand Challenge. . . the rednecks a Cannonball Run. . . and the Auto X prize is still a year away. So in the meatime, NASA scientists and junkyard fabricators will go head-to-head in a no holds barred battle of engineering prowess and creative excess. Hanging somewhat in the balance are bragging rights for saving the world. That, and a grand prize of $10,000.Schedule:June 12th - Race begins at ALL Power Labs in Berkeley, CA. End and overnight in Parkfield, California, the Earthquake capital of the world.June 13th - 2nd leg start at Parkfield. End and overnight at El Mirage dry lake.June 14th - Day off at El Mirage dry lake for landspeed trials. Some EFB racers to run speed trials.June 15th - 3rd leg start at El Mirage. End at Salton Sea, California State Recreation Area.June 16th - 4th leg start at Salton Sea. End at the beach where the fence goes into the ocean at the Border Fields State Park, US Mexico Border."Some entries will arrive at the start line with extreme technical innovation. Others will arrive with only creative excess. The best entries, as well as the likely winners, will need to arrive with both." - Jim MasonNew York Times article on last year's race.

Topic by StumpChunkman 10 years ago  |  last reply 10 years ago