How to lower the DC voltage of a transformer. Answered

Hi, at last i have got a 45-0-45 transformer @5amps, but now i have a problem, the VDC output i am getting is 74vdc but my 400watt rms mono amp's maximum input VDC is 56vdc, so i don't think its a good idea to feed the 74vdc, so is there a way to lower the 74vdc, BTW please don't advice me to unwind the secondary coil because i am new to electronics and the transformer didn't come cheap, so i don't want to break it. i am using IN4007 diode and 4700uF 63V cap for the bridge rectifier. ​I just forgot to give some details on this topic. The transformer is to use with the 400watt rms mono amp. The amp has 8 MOSFETS side by side, 4 IRFP9240 and 4 IRFP240 and 6 transistors. BTW the transformer shows 45-0-45 VAC but when i test with a multimeter, the VAC is 53volts. Thank you. Regards.

Question by Lima79   |  last reply

Rewinding a DC motor for different voltages

I modified small DC motors, like used in toys and such but now I have one that requires to do it properly.Motor in question runs on 24V and uses about 3.5A under full load.Drives a high pressure water pump on either side of the shaft.The rotor is basically empty with just a few turns of wire and lots of empty space.I assume the same model is used for multiple power configurations by the manufacturer.For the toys my basic approach was to just calculated the number of turns or to count them when removing.From there I get the voltage per turn and can rewind accordingly.So in theory and by blissfully ignoring all higher things involved I could do this motor the same way.Right now I see 10 windings per coil, so with thicker wire I would use 5 to run it on 12V at roughly the same speed.Only problem is that thing then would use around 7.5 to 8A when running under full load and get quite hot.I need the speed to keep the flowrate at the same 7.5L per minute but I also need the power to be able to still get the 120PSI from just 12V.Isn't there any winding trickery that would allow me to reduce the required current a bit without sacrificing on speed or torque?

Topic by Downunder35m   |  last reply

K'nex guns; Lower piece count, still great performance?

I love building with k'nex. I've always been fascinated by the k'nex guns on this site, but all the good ones need tons of pieces. And all of the simple guns are too, well, simple! I want to build these guns so i can modify them or even re-design them myself, but i can never find k'nex where I live, and I don't have a credit card to buy online (Parents would, but don't have the money themselves). So, are there any good guns out there that can be stripped of some parts, but maintain their functionality? I'd prefer something semi-automatic, with good range, but feel free to mention single-shots too. Revolvers, pump action, and chain feds would be awesome too. When i say stripped of some parts, I really mean bare essentials. If its not necessary for functionality, I don't want it.

Question by Mr._Rodgers   |  last reply

Heat transfer through cement

I have a garage on top of garage because my land is on a hill. The lower garage is all concrete all the way around including the ceiling. The floor in the upper garage is the cement from the roof of the lower garage. I want to heat the upper garage, but I know the floor will always be really cold because it is cement and the lower garage is not heated. The lower garage does stay quite a bit warmer than outside temps.My question is this, If I heat the lower shop, will the floor in the upper garage and the upper garage that is insulated be warm as well? Or am I better off just heating the upper shop and having a cold floor? I spend a lot of time in the garage and would like it comfortable when I am in there. ThanksJed

Question by jedidieah   |  last reply

Dog crate/protection/divider for boot of estate car - lower height to be covered by parcel shelf cover?

Hi there I'm looking to come up with a solution for the boot of my car so any suggestions you can come up with are welcome!  I have a Labrador and would like to have a divider/container for him in this boot, so effectively one side of it would be 'his'.  I would like to have the parcel shelf/cover able to be down as per the photo so that anything in the other section can be hidden from prying eyes.  The crate we have at home is too tall (26") and to get a crate with the right height (20") the crate would be much smaller in length and width and wouldn't be suitable for the dog especially when travelling long distances. We had a pen for the garden when he was a pup but it's too tall also. the dividers you can buy require a backseat grill effectively to be purchased alongside it so it attaches properly - adding cost and also losing my parcel shelf/cover capability. Any suggestions folks? Thanks in advance!  

Question by KirstyD3   |  last reply

how to design a wind powered water lifting system?

I need to lift water from the higher tank to the lower tank ( against gravity)...i difference between tank a and tank b is 20 cm only

Question by lulu114   |  last reply

Hoist? Answered

Any ideas for a small hoist to lift an air conditioner out of a window that is about 3 feet off the floor and lower it to the floor for transport to another room. It would be helpful if it was small enough to fold and fit in a VW trunk. It should have casters on the bottom.

Question by emit   |  last reply

What can I make out of a hospital gurney?

I have an old hospital/ER gurney similar to the one pictured minus the padding. Originally I planned to scrap it but it is just to nice. It has a very easy/smooth hydraulic lift and lower mechanism (non electrical) and it can be angled either direction (head up or down). The wheels are large and sturdy and can be locked. I hate to just scrap this when I know someone more creative than I can think of a way to convert the hydraulics into something cool/useful. Just to clarify: you use your foot to pump up the bed and press another foot pedal to lower it. Thanks for any help!!

Question by nasus123   |  last reply

how to put a jeep cherokee window regulator back in the door? Answered

i got the part out and put the new part together but i cant figure out how where to screw part of it in. In the picture it is the lower left part.

Question by gantyman   |  last reply

I need an AC Voltage Stabilizer?

I have low voltage at my place which keeps on going even lower at night. I need to create an AC voltage stabilizer to keep the power at the required level (230v 50Hz)?

Question by nabulomi   |  last reply

Paper cutter fix needed !

The cutter blade is now stuck in the up position and can't be lowered. Could I use the beautiful instruction on how to refurbish a similar cutter (but different brand). Seems daunting if there is a simple adjustment instead of removing every screw and hoping to get it back together. (first time site user)Thanks

Question by gale olson   |  last reply

How to open a Jack LaLanne juicer? Answered

I was given a motor to a Jack LaLanne juicer. How do I get inside? I want to repurpose it as a sharpener, but can't get to the motor shaft. I took the feet off the bottom, but the lower plastic end cap remains in place. Has anyone ever been inside one?

Question by vectorges   |  last reply

Marbles in a funnel?

Does anyone remember the museum piece that described angular momentum or some such thing? It looked like a large wooden funnel with marbles that were augered up from below and let loose to roll around and down, spinning up the lower they got? Has anyone made a home version of this? Can something like this be made into a coffee table?

Question by javajunkie1976   |  last reply

When installing a domestic pressure pump how far can the pump be away from the tank it's sourcing the water from?

When you install a pressure pump would it be possible to have the pump 200 meters away from the tank it's sucking from if the pump is lower than the tank by about 1 meter? Thanks in advance

Question by legend4930   |  last reply

Could I use a scissor jack and attach a mount bracket to the jack for a router lift?

I was looking at the idea of gears and router table lifts. i thought for 20 bucks and some metal it could be done to lower and raise the height of the router  tool attached to a car scissors jack. can this be done with accuracy? Has any one tried it?

Question by Speded   |  last reply

Bike too big

Hey all, I need some DIY help. I just rescued this road bike from a woman whose father was a racer, I love it but its just too darn big. I ride it comfortably standing, biut getting on it is quite risky. Any suggestions? I lowered the seat. I don't know what else could be done, but I'm hoping!!

Topic by itsdori 

Is this 4-Sided Diamond Hone Block any good? Answered

4-Sided Diamond Hone Block  I was wondering if it would be a  good idea to use this to polish up my katana that I'm building. I already have a whet stone but it powders easily and seems  to not be able to handle the job. also it takes forever i want something with a lower grit.

Question by the_burrito_master   |  last reply

3d printer?

Two ideas wondering what people think.... 1. Have the up/down bed for a 3d printer go up and down with water... Just have a little valve that lets water out and the printing bed would slowly lower. At whatever speed you wanted. Could work the other way and fill up. 2. Have the extruded plastic print into water... it would cool instantly and might help with resolution? Just an idea. 

Question by bellinghammakerspace   |  last reply

[ask] Blinking led advantage

Hi all, i want to ask in order to use less power (voltage, current or watt, i'm confuse about that) to light led. If i power up 100 leds blinking in parallel, blinking one by one, 50 hertz or higher, Am i get kWh (kilo watt hour) lower value instead powering 100 led without blinking...? Thx

Topic by shinjiyuubix   |  last reply

Washing machine motor on an electric vehicle?

Hello, i already asked a question about a car starter as a Motor for my Electric bike project. I got bad news from the answers, so I wanna use a washing machine motor.  My question is, do i need 240V to power it? Or it has like a transformator in the washing machine that makes the voltage lower? I never opened one..

Question by dsirotic   |  last reply

Does someone have engineering drawings for a gas-spring lift-assist assembly (horizontal platform)? Answered

I have a long-dormant project for a "powered" tricycle carrier for a car trailer-hitch. It occurred to me today that a piston "lift-assist" device could do the job. I wonder if anyone here has a technical design for a lift-assist assembly that I could use to understand the mechanism better. I need something that provides lift assistance both raising and lowering (maximum 10 lbs user force either way, for a ~50 lb load).

Question by kelseymh   |  last reply

Trying to make a black light mirror the magnitude of speakers Answered

Trying to make a black light mirror the magnitude of speakers, not just on or off if the sound is loud enough, I'm trying to make it get brighter and dimmer as the music gets louder and softer. Help please? I can't find anything online that would be variable, all I can find is guides for LEDs, which are much lower power than anything I'd like to use, and guides for modules that simply switch on or off like the clapper. Any advice or ideas would be greatly appreciated

Question by moses324   |  last reply

Turn an ATX Power Supply in to a Welder? Answered

I was wondering if I can turn an ATX power supply in to a welder: Before I write down the specs/amps of the power supply, I want to say that I have no experience in welding, I'm wondering if it's posssible to make a small welder out of an ATX power supply. Is there some kind of minimum current that you have to pass to start welding (softer?) metals? The lower the voltage the better right? I didn't give a lot of information, Because I don't know what to ask... Thanks :)

Question by Yonatan24   |  last reply

How much water does it take? Answered

i was   curious if  anyone could  tell me    how  much  water   (pressure/ volume)  it takes   to turn  a  small  hydro  power generator?   I ask because i  have  about 120 ft. of fall  from   the  top of my   property  to the bottom.  I was curious   how  hard  it would   be    be to  gravity  water through  a  hydro station    at  the lower  end. I plan   on reading up  on  some     small  generators , but  thought someone has   probably already    knows  the answer.The  ones   i seen   on another post   did not    get into the   pressure    volume   information. Thanks  for any help  you   could   give.

Question by andy1917   |  last reply

Hydraulic or air powered carousel horse, is it possible?

I have a niece who is fond of carousel rides, and I wanted to try to make her a fun ride.  Is it possible to have a hydraulic system (Like the ones they use in lowriders, perhaps...) or air pump be used to raise and lower a carousel horse while someone is sitting on it?  My initial idea is this... I turn a switch on starting the pump, and the horse slowly raises up about 1 foot... turn the switch off, and the horse goes back down, repeat, etc....  Anyone knowledgeable who could help me with this?  Thank you!

Question by Isabelle356   |  last reply

Can a charger made for 1600mah batteries safely and effectively charge 2500mah batteries? Answered

I have several dead battery packs for my 18v power tools.  Planning to rebuild them and figuring I might as well upgrade their run time while I'm at it.  The original battery packs are 1600mah but I can get 2500mah battery cells that are the same size for about the same price.  1) Will I still be able to charge the higher capacity batteries with the charger that came with the lower capacity ones?  2) Will it charge them to their full 2500mah capacity?  3) Will it be able to detect when they are fully charged?  4) Will it give a false positive and think they are fully charged as soon as they reach the 1600mah of the original battery packs?

Question by etcmn   |  last reply

Limiting current?

Good day, I am interested in an effective way of limiting current for a TEC application. This application involves using the TEC's (12V @ 1A) to reduce the incoming air temperature in a noise isolating enclosure from ambient temp to about  5-10 deg C cooler. In doing some research on implementing the TEC's I have found that these units operate at their greatest efficiency around 1/3 of max amp input and lower when you do not have a large heat load to "pump" away. So all of this being said I would like to operate a number of TEC's at  this low amperage range, and to be able to cap their maximum current draw between .1 and .3 amp.  Any input would be greatly appreciated, thanks

Question by MatthewSternbauer   |  last reply

New Vacuum Pump Idea

I have a new idea about a new type of positive displacement vacuum pump.  Its of the piston variety, but instead of a one way valve which doesn't work when the pressure gets low enough, another piston is used to act as a valve switching between the vessel to be evacuated (when the main piston is pulling a vaccum) and the atmosphere (when the piston pushes the air evacuated out). This solves the one way valve problem.  Could this pull a much lower vacuum?  I need a fairly strong vacuum, but I don't want to have to build/buy a turbomolecular pump. Also, i have a metal lathe, that's why i'm going with the piston variety.

Topic by guyfrom7up   |  last reply

Electricity over IP

This is not really a new concept (first published in 2002), but one to mull over :-) Electricity over IP (EoIP, pronounced "yoyp") is a proposed scheme for delivering electric power via IP (Internet protocol). EoIP was developed to eliminate the unnecessary redundancy inherent in maintaining separate distribution networks for electricity and the Internet. The technology could be especially beneficial in remote areas with Internet kiosks but without electricity.The architecture for delivering EoIP is known as MPLampS (Mostly Pointless Lamp Switching). Electricity is digitized and encapsulated in discrete packets. According to the IETF's marketing segment, "MPLampS has the potential to dramatically lower the price, ease the distribution and usage, and improve the manageability of delivering electricity." Electricity over IPThe IETF Network Working Group described EoIP in RFC 3251, published on April 1, 2002. April 1 is also sometimes known as "April Fools' Day."

Topic by Goodhart   |  last reply

Work table/bench for working on lawn mowers

I've searched here and elsewhere without any luck. I'm looking for a design for making a table/bench about 20 inches high for use in working on lawnmowers and other items that require a lot of bending or stooping to reach. I'm nearly 80yo and have a pinched sciatic nerve in my back. I can't stoop or kneel (replaced joints in knees and hip) for any length of time without painful consequences. I'd use a stool or chair while working.In the vein of not re-inventing the wheel, I thought I'd ask around before attempting my own design. Two important features are 1) a ramp or hoist to raise and lower the mower/whatever; 2) a lazy susan type table top. I don't have a welder so the thing would have to be made of wood.Thanks,cb21

Question by Cueball21   |  last reply

How to choose the right capacitor for Harbor Freight AC Welder to DC Welder conversion? Answered

I'm watching this series of videos about improving a cheap harbor freight welder. Right now the step is converting the AC to DC. It seems like the guy is just using whatever components he has laying around or that are the cheapest but I want to make sure to get the most power as possible. Here's the AC to DC conversion video:;=PLd_DTtq1stJJ4C0qlUnxqBvrfLXLKDyYr&index;=1 Here's a link to the Harbor Freight page with the welder specifications:;=PLd_DTtq1stJJ4C0qlUnxqBvrfLXLKDyYr&index;=1 It says on the specifications page that the open circuit voltage is 26 volts, does that probably mean that that's the max output voltage at which the welder operates? Anyways, here are my questions: 1.Can a capacitor be fully charged by a lower voltage than it's rated for? For example, the modification in the video uses a 50V capacitor to store charge from the transformer of the welder, which I'm assuming is a 26 volt or less source. Will it still reach it's 46,000 microfarad charge storage potential or does the charge storage potential vary based on the charging voltage? In which case could the capacitor store more charge at a higher voltage, a lower voltage, or wouldn't it make a difference? 2.For the rectifier, assuming the max output of the welder is 120 amps at 26 volts, I am thinking that the guy in the video should have used a rectifier rated for at least 120 amps, probably somewhat more than that to be safe. But instead he is using a rectifier rated only for 100 amps at 1600 volts. That's it. Basically what do you think of the modification. Are those components in the video adequate, the rectifier and the capacitor, or if doing this modification would you have selected different perhaps higher rated components. I have a habit of thinking that I'm too smart to follow instructions exactly and then wondering why things go horribly wrong when projects, recipes, etc. don't turn out.

Question by avocadostains   |  last reply

How can I make an AC adapter that will fit a standard 1/2" drive 18V DeWalt drill?

I am sick of buying batteries or having them not stay charged very long. How can I make an AC adapter that will fit a standard 1/2" drive 18V DeWalt drill. I want to drop 120 volt to the 18V (with lower amps?) and do it in a hollow battery house so it will take the place of a battery when I run low on charge. You would think a cordless drill company would offer something like this as an accessory. I bought a cordless drill for the convenience, but 9 times out of 10 I am still close to an outlet. If I don't get an answer here I will just go ahead and figure it out on my own. But I really don't want to have to re-invent this wheel if someone has already done this.

Question by bobhdus   |  last reply

How to make Finches - Love Bird Incubator

Hi, I have read many blogs on how to build our own small incubator for my finches or hen eggs. The problem is every blog, instructable, guide shows to put 25 watt bulb, but my question is.. Is there any possiblity to put some automatic thermostat which gets on when the temperature is lower then desired  temperature (eg. 102-103 degree fahrenheit) and the thermostat should shut down when the temperature is reached to desired temperature. Using bulb can not be effective in different climat condition and after a long run it becomes very hot inside the incubatore, plus it needs extra attention during the incubation period. I checked on net for this type of automatic thermostate but it is too costly and basically made to control for room temperature. Any guidance on low cost automatic temperature control where a user can set temperature for low temperature of appx 100-103 degree fahrenheit would be much appreciable. Thanks in Advance. Rohit

Topic by Rohit.Agrawal   |  last reply

Long term experiment - Transplanting lichen.

  Lichens are fascinating things.  They are a symbiotic association between a fungus and an algae and can be found growing just about anywhere if you look.  However the varieties which will thrive in a specific area are determined by the air quality as certain pollutants will kill certain lichens.  You will find the cleaner the air, the more species of lichen you will find. I picked up the lichen-rich rock in the picture from the lower slopes of Pen-Y-Ghent in Yorkshire (UK) and took it back to where I live in the Cotswolds - A rural area in Gloucestershire and around 200 miles south of the rock's 'home'.  It now resides at the top of a dry-stone wall bordering our drive. I intend to photograph this rock every six months to see which lichens thrive and which decline and whether any transfer across to the surrounding limestone of the wall.  The first photos were taken in early August.  One photo shows the lichens already established on our wall which has been there 16 years.  I'll update this topic with new pics in Feb 2012.

Topic by AndyGadget   |  last reply

Bass (guitar) signal spilt + combine

Hello I have been thinking about a project that I would like to try. The idea is that I would like to be able to take the signal from my bass guitar and split it in two (configurable how much signal in each, but the sum should be 100%), apply an effect to one of the lines and then combining the two signals again having only applied the effect to some of the signal while carrying the clean signal through. This way I could apply e.g. distortion to only 20% of the signal. I thought that I could control the volume simply by putting an resistor in the signal line, but this gave quite some noise. This is my first attempt at building electronics for instruments, but have some experience with electronics in general. Hope you can help me with a couple of questions: 1) Shouldn't you be able to lower the signal simply by resistors? Should you use any specific resistors for audio? 2) Is it possible to recombine two audio signals and can you just put the wires together? Kind Regards Brian

Topic by FatMooseHenry   |  last reply

Is it cheaper to pump water or buy it?

Considering a height difference of say about 15 feet would it likely be cheaper to pump water from a lower elevation (such as a creek or pond) to a higher elevation or would it be cheaper to fill the reservoir with city water which is already under pressure. This is all just theoretical but would the cost of running the pump be more or less than the cost of buying the water?  Of course other factors would play in such as the city water being bacteria and sediment free (in theory) but im ignoring them for now.  Any insight would be appreciated since I have no idea of relative costs for either right now.? Edit: Maybe I made it seem a bit too formal but I am just talking about putting a pump in a lake or creek with a garden hose attached vs turning on a garden hose connected to city water.  Im not trucking it in or anything.  I dont have specifics as said but if the answer depends on specifics then that gives me enough of an answer to know that i will need more research when ready and that its not easily one or the other.  Thanks.

Question by kinderdm   |  last reply

How to grout uneven glass tile?

I have installed glass "wavy" tiles around the walls of a bathtub/shower.  Each wavy tile is about 2.5" long with a square piece of marble between each glass wave piece.  They are arranged on a 12" square sheet of mesh in a basket weave pattern and each of the pieces are butted up next to each other (leaving no room for grout).  The person at the tile store told me that I didn't need to grout it.  However, given that it is in a bathtub that also used as a shower, I'm thinking it will need to be grouted so water doesn't get up under the tiles and loosen the tiles over time.  Three questions: 1) Do you agree that I need to grout?; 2) How do I go about grouting this wavy tile (it is very uneven... the lowest part of the wave of each tile is 1/8" lower than the top of the wave); 3) As an alternate to grout, is there a clear product I can put on it that will seal up the spaces between the tiles without ruining the shiny finish of the glass?

Question by daltexson   |  last reply


Hello,I'm Marcin from Greece. I saw yesterday a video about a interactive speaker cloud,but is too expensive for me.I started search about how to build one and I saw Arduino think. (I don't have any experience about it but with instructions I believe I can make it for my nephews) That is my project: I think to use led lights and speakers 2.1. I want to sync the woofer with a specific led strips that gonna make a bright white/light blue light when a loud lighting strike hits and then the following sounds that happens at lower volume to light up the others leds,and some times some random lightening lights. All of those thinks to sync with a sound effect of raining and storm that I will download from YouTube and can play for 1 hour and more. Maybe inwill use ceiling power supply so please someone tell me if that is possible to me to make it and how much gonna cost and if anyone can guide me about what I will need and the commands.Please if anyone can,really I want to make it for the kids because they love it when is raining and hear strikes.Love from Greece.SORRY FOR MY ENGLISH.

Question by marcin93 

capacitor bank questions.

Hello all, this'd be the first post i've ever made, and may be in the wrong place....... edit- i guess it was in the wrong place, since no one replied.... so i'll try here.... i'm tryin to make a cap bank from 30+ flash cameras (possible? possible outputs? how do i calculate that?)  and i have some question/problems. is it possible to take a bank like the above and use as a spot welder?   if so, how would i trigger the spark without the trigger becoming the spark gap?  another possible use i have for it is a rail gun...... theoretically, if counter evidence isn't provided by all of you much more tech inclined ibblers a second concern is that the caps come in at least three different micro farad ratings. would one explode if it's rating is lower than the higher ones?  (the ratings are between 80ish to 150 ish (don't remember)) i rather need the weilder for a possible steampunk project that i just bought a bunch of metal junk for....(knowing me though, i'll never get around to doing it....)

Topic by badideasrus   |  last reply

Will my metal welder work ok?

I'm totally new to metal welding but am going to give it a try. My oven/range has a power outlet that reads on it: 125/250V, 50Amps. It has four prongs, three vertically oriented flat ones aligned as a triangle with the center one lower than the other two, and a fourth one top center that's round. My breaker box shows a 50Amp breaker for it. The welder says it's a MIG 170, 240V AC, 20Amps,single phase, 60Hz (Harbor Freight). I think the power I have is actually 220V but I'm not sure. If I do only have 220V will the welder only draw as much voltage as is asked by it - that is, if I only crank it up, say 3/4 of the way, will it draw less than its rated 240V? Or is that 240V just a maximum rating and it should run ok with 220V? It would seem odd that they would sell a welder that won't work for the power their customers would have by default without modifications. Also, where can I get a double socket for that outlet with one having an extension so I don't have to pull out my oven every time I need to weld something? Thank you. Bretina

Question by Bretina   |  last reply

Curious striations on avocado sapling trunk...?

Greetings I started growing an avocado tree from a's at least 8 months old now.  My roommate said it was important to nip off some of the top shoots so that it would get stronger lower leaves.  After it got about 20 inches tall, we nipped off the top, and now a few weeks later the top half of the trunk is showing signs of what I can only assume is infection. The bottom of the stalk/trunk is quite strong and stiff - as are the 6 or so leaves coming from it.  Above that, where the newer leaves are, the stalk is mottled with 2-5mm long dark spots running vertically, and all the leaves in the area with the spots are paper thin, slightly translucent, and very weak.  On top of them they have a waxy shiny sheen, where the healthy leaves do not.  The healthy leaves are quite erect sideways, opaque, and vibrant dark green -  while the weaker leaves droop almost vertical, are translucent, and lighter in colour. Is it an infection?  Is there anything I need to worry about?  Is there anything I can actually do? Pictures:  1) Good bottom 1/3 section 2) mottled middle 1/3 section 3) mottled top 1/3 section

Question by frollard   |  last reply

50-45V 1200mA Ac to 12V 1000ma

Hey. So i have this led light panel which was damaged by some water that leaked through my ceiling from heavy rain.My dad wanted me to try repair it(he didn't want to spend another 100$ to buy a new one) so i did and i found in that the led panel has 4 strips of ca 70 leds each 1 m length each, powerd by this guy 2 of those led strips wouldn't work anymore so i had  one led strip of 2 m which i bought for some project , and  i wanted to replace the ones that aren't working anymore but they are working pretty well on 12V 1000ma Dc(they are heating pretty fast but for that i think i will need some resistors for that or i don't know). So i'm asking how can i convert 50-45V 1200mA Ac to 12V 1000mA Ac so that i won't burn that led strip that works on lower current. A schematic will be all i need and the components that requires. P.S : I'm a begginer in electronics and i don't know that much about them and i'm looking forward in learning more sorry for the long story.

Question by valexandru1   |  last reply

City Flying Taxi

LINK"Developed by the British company Avcen, the Jetpod is a small twin-jet aircraft with newly developed VQSTOL (Very Quiet Short Take-off and Landing) technology - and it’s aimed to make short-distance air travel possible in built-up urban areas by the year 2010.""75 Jetpods would service a city the size of London and thereby relieve road traffic of 37,000 return car journeys every day. A one-way flight from outer London to the city centre would take just 4 to 6 minutes. The Jetpod doesn’t even require a conventional runway. It can land on grass, dirt or stone-strewn areas. Avcen designed the Jetpod using the latest jet engine technologies for optimal fuel efficiency and lower emissions noise levels, when compared to car transportation.TECHNICAL SPECIFICATIONSDRIVE SYSTEM: Dual jet enginesENGINE THRUST: 2 x 13.3 kN (3,000 lbs)CRUISING SPEED: 550 km/h (350 mph)FLYING RANGE: 1480 km (920 miles)OPERATING PAYLOAD: 700 kg (1,543 lbs)SEATING CAPACITY: 7"This is pretty cool, can't wait to see if it actually gets into production.

Topic by laminterious 

Voltage regulator to get from 70vac back to 120vac?

Hi all, I am using (and for strange reasons am required to use) track light outlet adapters to power some LED light strips. The LEDs use an AC adapter that requires a minimum 100vac to run properly. The problem is that the track lights are dimmed substantially, so the voltage coming from the tracks is only 70vac. Any idea what I can use to bump the voltage back up to the 100+ voltage range? Tripp Lite has a some regulators, but they don't go down to 70vac. APC makes one that goes down to 80vac, but that's the lowest I've found. Is there an off-the-shelf regulator that goes down to 70 volts? I found this contraption that looks promising and maybe a little sketchy (alibaba style). Any other recommendations? I guess the other question is what is the risk in running the LED strip lights if their AC adapters are getting 30v lower than they recommend? The lights appear to function fine, but will the adapter overheat? Burn out quickly? Cause a fire? If it burns out, say, once a year, I'll probably leave it, but I have no idea what the consequences are. Thanks in advance! 0    ..    o uuuuuu nnnnnn

Question by uuuuuunnnnnn   |  last reply

Repair on a Russian Belarus farm tractor?

Sirs, In 1990 we purchased a new Belarus tractor, made in Russian.  It came equipped with a large front-end loader and really for the most part it has been an economical, dependable tractor.  It has one small flaw, it doesn't like to start in cold weather, hard to believe they use these tractors in Russia.  Anyway my husband solved that problem by installing both a block heater which heats the water & an oil pan heater which of course heats the oil.  Only thing necessary is to either keep it plugged in all the time or plan ahead and plug it in the night before.  Now for my question, the seals on the arms which raise & lower the loader bucket and the ones that tilt the loader bucket are leaking hydraulic fluid.  Can anyone help us in changing the seals.  We ordered and received the necessary parts, but would like help with specific, very detailed step by step instructions to perform the repair.  It is our understanding the repair can be difficult if one is not careful in removing the end caps that hold the hydraulic cylinders.  Also the cylinder caps are external ones & the diameter is 40 mm.  Any and all assistance will be GREATLY appreciated.  Thanks so much, Debra Kay

Question by Debra kay   |  last reply

Tired of dumping dehumidifier... Float switch, submersible pump, and a timer?

I have a small dehumidifier with a removable tank that has to be emptied far too often.   It has an integrated float switch in the tank that shuts down once full, but if you neglect to dump it, the basement gets way too muggy. I would like to put in a submersible pump (like this) that is activated by a simple mechanical float switch.  Once activated, I only want the pump to run for a set amount of time, in order to keep the pump from pumping all the water out and running the pump dry.  I thought about this timer, which has a minimum interval of one minute.  One to two minutes of pumping would be about right for the tank size, depending on the pump flow rate and where the float switch was set to initiate the pump. I had originally looked at a Kerick Valve float switch, but this will only let enough water drain out to lower the float and close the valve.  This will essentially just trickle out. Any ideas on this? I don't want to drill a hole in the tank and just run a drain tube... though I considered it.  Part of the reason is that I wanted to avoid just letting it trickle out.  And I also felt like I wanted to tinker just a little.  :)

Question by jmgustin   |  last reply

How clouds act as an air pump to suck in air. Not how you think they do!

I have been thinking a long time about the biotic pump theory but I still don't understand it.  The math is too hard for me.   BUT it got me to thinking.   It is a point of major dispute in the meteorological world.   Does condensation cause low pressure?  2 russian nuclear physicists say yes,  almost everyone else says no!   So,  I thought and thought and thought.  Now I think I have a simple enough explanation And yes, they may not necessarily cause low pressure under the cloud (probably do)  but they definitely suck in air from elsewhere.  Imagine a fleet of huge doughnut shaped dirigible airships. They are sitting at 10,000 ft just floating there.   Now the commander tells everyone that they must now fly at 5000 ft.   So they turn on their propellers (in the hole in the doughnut) and drop down to 5000 ft by propelling air up  through the hole.   Now staying at 5000 ft is achieved by running the propellers at just fast enough.  So at 5000 ft they are pumping air from under the doughnuts to above them.   Now imagine a cumulus cloud.  Even though it is not fixed in size or shape and it does not have a propeller,  it is doing the exact same thing.  Air is being pumped up the middle and the clouds are sitting lower in the sky than they "should",  because they are sending that column of air up into the sky.   Here is my video to explain it visually.

Topic by gaiatechnician   |  last reply

How to choose wire gauge for Brushless DC motor?

I'm planning to build a Brushless DC motor, with inrunner perm mag rotor and stator on the outside. How can i determine the proper copper wire gauge for the stator windings? How much current will the motor pull? At first i thought it was just "Power = Voltage * current", so knowing the power and the voltage i should be able to figure the current. However, when the motor is spinning it generates back EMF, which counters the applied voltage and diminishes the current. At no load, the motor should draw no current for an ideal motor, and only a small current in real life to overcome friction and losses. In any case it would be much lower than the nominal current. So, for instance, a 1000w motor at 50v should draw 20A nominal, but in most situations it would be less than that? How much is the starting current, when you have to overcome inertia/tire friction? I know the motor can take higher currents for small amounts of time, before it gets too hot,but how can i determine what will be the "average" current. Is there a rule of thumb that motor designers use?  Also, the amp rating for each AWG seems to vary a lot. Some places list a conservative rating that is used for home wiring. But other places list much higher currents. If the stator is on the outer side and exposed to air, how much current can the copper handle for each AWG? Any insight will be appreciated, thanks.

Question by SlickT   |  last reply

Robo-Goat Lives - At least I hope he Will

OK here goes. I work at zoo and I am a self taught geek, (mainly old school). I recently volunteered for a project mainly because I'm too stupid to know that it's not possible :~) Purpose of the program/project To - Engineer, Design and Build an Animatronic Robot Goat for: a Cheetah Conservation Fund in Kenya, Africa. This device will replicate a live goat in: size; appearance; movement; sound and smell (smell supplied by others), that can withstand the sever conditions of the desert, durable, possibly solar powered and easy to transport, setup and operate. Note: Up until this point real goats have been tried but they have not been too successful. They were either too stressed or they were stolen for by locals their meat. Objective(s): To lure Cheetahs into an area and enticement them into a cage trap with a simulated live goat (Robo-Goat), to provide a safe humane and ethical capture of wild cheetahs so that recently acquired state of the art GPS/Cellular tracking collars can be placed on them to help gather information to preserve this endangered animal. Analog Radio Tracking Collars have provided the only way to gather much of the information for many different wild animals. Radio Tracking style of the past has always been a difficult and time consuming endeavor, with old style tracking, large heavy radio collars that broadcast a ”beep” continuously, must be tracked with specialized hand-held radios and yagi antennas. All this to locate an animal being studied. Many times you would have to get close enough to disturb the animal just to find out where it is and then try to track it. Obviously not good “normal behavior” data gathering. The new GPS/Cellular systems track the animal in real time and send back data coordinates on the animals location, elevation, speed and direction as it travels. This GPS information is sent via cell towers, (yes they have them in Africa), to a computer that logs and graphs the movements. The research gathered through these efforts may provide the answers to saving these endangered animals. Project design/methods: #1. Establish parameters Record video & audio movements and sounds of normal & panicked goats Research and study movements and demonstrate what mechanical requirements will be necessary to replicate the minimum needed movements - [DONE]. {Raise and lower head; Look left and right; open/close mouth} Determine movement engine {I'm not sure here} {All of the movements are really axial in nature} {At first I was thinking motors but then there are end stops, control systems, ect. To deal with} {next I'm considering solenoids for the low energy requirements and simple full scale movements, except you cant control the speed} {But now I am becoming fixated on model airplane actuators for low weight, low noise and appendage like joints and accessories} {then I ran across "pager motors" and how they are small powerful and inexpensive some how I don't know where to begin} {can you tell this is all still up in the air?} Throw distance & Speed of movement - [DONE]. {Raise and lower head = 90 degrees of arc from base of neck = 5 seconds max} { Look left and right = 90 degrees of arc from left to right with return to normal center point half way = full movement l-r = 2 seconds max i hope} {open/close mouth = 45 degrees of arc from lower jaw = 1 second max} Repetition rate & pattern {random if possible} Determine audio requirements - [DONE]. {this is easy but requires playback trigger synchronized with mouth} The Cosmetics: Determine body and outer skin requirements – [Engineering]. {aluminum wire frame mesh} {foam sculpted head for low mass} {foam wrap suit for body & legs for low mass} {tyvek skin, airbrushed or penned for low mass} {stainless steel / nylon joints for low mass} DB level of normal and panicked goats - [DONE] {I have determined audio system requirements} Determine control system requirements {clueless at this point} Determine power requirements {I'm thinking deep cell marine battery and solar panels to retain charge autonomously} {amp hour rating for battery and solar charging circuit TBD after R&D; tests} {if solar is not feasible them battery exchange schedule TBD} #2 Acquire all electronic and mechanical parts #3 Create mechanicals Fabricate lightweight frame and skeleton structure. Assemble motion joints and motion engine Assemble and test motor functions Determine estimate of MTBF for spare parts, if any #4 Create & install sound system Edit custom audio media for both normal & panicked goats Utilize 12v Solid State Audio Playback Unit # 5 Create Control System #6 R&D; Testing Test charging and power circuit Final assembly #7 Final test Any help to provide suggestions to get me started on the type of engines would be great. tia

Topic by sharpfocus