how to reduce current ?

We designed a circuit . But it is drawing 70mA of current. I want tot reduce it for atleast 30-40mA.

Question by SunnyJ1   |  last reply


I am currently building an RC hovercraft, I plan to use a single 12 volt 2.1 amp hr lead acid battery to feed both the lift fan for the skirt and the power motor for the drive. However the fan for the skirt is 12v 0.3 amps. How can I reduce the feed to the required amperage with out affecting the other feed from the same battery that will power the drive

Topic by Seafarer77   |  last reply

cutting 53.9 volts dc to 12 volts dc like a car uses

I own an electric scooter the problem is they desided when they bult it that it would use a 52.9 volt dc light which I can't go any ware local and buy I need to bring the dc volts down to what a car uses then I can so the that kind of light bulb for a car can some one could please tell me what electronic parts I would need that would be of great help you can contact me @ ?

Question by Cleasonsook   |  last reply

Active Noise Reduction as Software--possible?

While on vacation last week, I was trying to watch a sophisticated, complex movie (something with Muppets) on a laptop and was having trouble hearing the audio through headphones, due to the general loudness of my family.Is it possible to actively reduce noise through computer software? I assume that the programming itself would not be too complex, but I don't know if the time taken to process microphone input and use it to modify audio output would be too slow. The only place I found through Google that discussed this was a forum wherein the members couldn't get past the concept of attaching a microphone to a headset. I also found a schematic with instructions for building headsets, but I would prefer a .exe file.

Topic by CameronSS   |  last reply

Options to improve cooling and reduce consumption for portable coolers

I recently had to start learning how to service airconditioners on the fast and that learning got me thinking about my portable coolers.... Some of us like to go camping or on longer fishing trips, so there might be one of those 3-way fridges in use or a better cmpressor model. The one thing they all have in common is that they can only cool down to a difference in ambient temperatures. No matter which way we turn it the cooling produces heat and that needs to get away somehow. The other big thing is the cooling cycling - or the lack of it on a warm day. After some reading and thinking I came up with some ideas that might be applicable to your existing cooler if you are willing to mess around a bit. Let's start with the produced heat, shall we? Down here in Australia most people either have the fridge in their4WD or camper. In a car or small camper trailer there is often the problem of airflow, so the cooler might be doing overtime for no other reason than a lack of airflow. If you check online sites like Amozon and Ebay you quickly find fan systems meant to be installed inside the cooler to get lower temperatures and a quicker cooling of fresh goods. The thing is that the box is quite well insulated and the benefit of the airflow goes only as far as it can reach. And even if the box is quite empty and you would have a benefit of the cold air moving around it won't change the fact that "improved" cooling always comes with more heat in this case. But if we use one of these fan systems to actually improve the airflow on the hot side we not only get better cooling but also a reduce power consumption - something worth considering if you have no backup power generator.... This of course brings us to placement. As I have done the mistake myself you might be tempted to put a 3way cooler onto your seat. Opening it with the back free means the lid always gets stuck on the seat, do it the other way around and you block the airflow. If you do put it on the seat then make sure two things match: 1. The thing is secured properly. 2. The airflow from your aircon is able to reach the hot side of the cooler. Even permanent installations in a camper benefit from a good airflow. Often the fridge or freezer is built into some sort of bench and the airflow behind might be very limited. A simple solution here is to add a vent on top of the bench to allow the hot air to escape. A better one is to use a fan that is powered together with the heating element or compressor and drives the hot air to the outside. How to improve the cold side of the box or fridge? Well, to be honest there is not much that can be done unless you are prepared for some serious work. Depending on compartment size, contents and how full it is a little fan can help to keep the temperatures even but it won't help to get it cooler or reduce the cycling periods for the cooling. The only really working way that I found is to use a "battery" for the storage of the cold. The cooling works by checking the inside temp of the box and if above the set temp the cooling won't stop. This is all well and good while we have a constant supply of power but once we are on batteries it would be great to keep the active time to a minimum. A working solution is to build a container that fits around the cooling element. Smaller types often use an aluminium heatsink, bigger types might come with a compressor and an evaporator. In either case proper sealing is important! Most good models are fully waterproof, meaning even if you would fill them with water they would not leak in other areas than the door. But double check and if in doubt use a bit of silicone to make sure. Ok, but how do we "store" the cold coming from the device? Cold packs ;) These things contain a ready to use mix that holds cold temperatures quite well. Another really good alternative is alcohol or radiator coolant, although the last has limited capabilites in terms of holding capaity for the cold as it is desinged to exchange heat fast rather than to keep it. With a suitable sized and sealed box around the active cooling element we will need longer to actually see any cooling happen (with a warm "battery") but that can be compensated for by good planning or a frozen water bottle. If the cooling element is covered with a box of cooling gel then it has to cool this first before anything happens inside the box. But once it does the pack is already far below the normal temp it would have during normal operation. Remember the inside of the cold pack cools down first before the outside will get cold ;) So once the set temperature is reached the device will shut off. But since the cold pack is far below the set temp it will continue to cool our box until the core is warmer than the set temp. Quick thinkers will now say the benefit is lost as the time required to cool the "battery" down again is much longer than the normal cycle time - and they would be correct. But as we get much colder temps inside the gel box the overall running will still be less compared to normal operation. And since from the second cycle on the gel is only warming up to operating temp of the box it will be much faster than with a warm box. Another benefit might be the ease of cleaning and ice removal. Some peltier driven coolers have big cooling fins or a quite bad design for the heatsink allowing mould to grow where you can't remove it easy. If the box is made from stainless steel and flush with the back wall of the box we won't have that problem anymore. Ok, but how much is good or too much for the size and gel content? You got me there as it is bit tricky. You don't want to loose much usable space for starters and you don't want to wait hours for the gel to cool down if the box was not used. IMHO the size should fit the cooling element with about 20% to spare all around. If stainless steel is not an option than aluminium is the next best choice. Thin sheets can either be be cold formed with a hammer or "brazed" with a good torch and the right rods. Ok, before that route is there anything I should consider or do first? Depends ;) 3-way systems usually use a flame or heating elements to heat an ammoia solution. After years of neglect corrosion can form and reduce the amount of heat transfered into the system and reducing the efficiency this way. It might help to take the heating elements out once a year or so to clean them and the contact areas from any corrosion or dirt build up. With a fixed shedule for this you won't have the problem of never noticing a badly corroded heating element either - and this is the main failure on these systems.... Modifying your camper or making a few mods to your 4WD drawer system is not for the faint of heart and should be done with consideration. The last thing you want to do is rush things to find out it was not necessary. Before cutting holes check if you can't find the room for the fan in a different spot and use ducts to control the airflow - sometimes it is easier to blow air in than to get air out ;) When it comes to creating vents or connections for air to the outside always make sure it is waterproof and insect safe! If you can let the outlet go downwards so water won't run in, for 4WD trailers consider a flap to prevent water from going during a river crossing. Flyscreens will not only prevent insects from coming in but on the inside also prevent dust to go eerywhere - allow to the removal and cleaning! The salts used in these cold packs can be corrosive, so you have to make sure there are no leaks and that there is no steel to come into contact with gel - this includes screw ends hidden in through-holes. If in doubt use a coat of paint but keep it as thin as possible. Even on peltier systems it might be impossible to remove the heatsink without massive surgery on the internals. So before you take it all apart to gain access check if it is far easier to seal around the box opening and possible screw connections using silicone. The cooling battery can be screwed on and sealed with silicone as well as an easy escape route. Although for this to work you need to check if the material of the box allows for a proper bond with the silicone! Some materials just won't allow anything to stick at all, even after sanding them. So do a test first in an area where you would be able to cut the silicone away without causing damage. If you can rip or peel it off the surface you should not try to use a cooling battery screwed to the wall, only use a box that is fully sealed with the cooling element and has a seperate back - one complete unit around the cooling element. I have a 3-way system with a freezer compartment that does the cooling for the fridge too - what can I do? These units either provide good freezing with the fridge temps too low or good fridge cooling with no freezing capabilites - depending on the thermostat used. Our problem is that is next to impossible to add a cooling battery of the normal kind to these systems. The L-shaped freezer box can really only be added with a L-shaped cooling battery from underneath. Only if you don't need any freezing at all you could add a cooling battery to fit into the freezer box shape. In either case the benefit is somehow limited by the way the thermostat is used. If there is no temp control for freezing it should be fine. Warnings... Only peltier driven coolers are free from refrigerants. Every 3-way or compressor system uses refrigerant as evident by more or less piping and heating elements. Never attempt to screw anything into a cooling element containing refrigerant! Even if you think between the channels all will be fine it won't be! The material is just pressed to form the channels and any damage caould mean refrigerant leaking out! Use silicone instead and make sure all surfaces are properly cleaned before applying it, also wait until the silicone is really fully cured before putting any stress on it. As said, these cooling gels can be corrosive, especially if DC voltage is involved. Make sure that everything that is not aluminum or plastic is properly sealed before allowing ongoing contact with cooling gels. Do not attempt any of this if you have to ask yourself what tools you might need or how make a suitable container for the gel. If in doubt check Google on how to work with aluminium or stainless steel if there are not enough Instructables for it. The gel will expand a little bit if it freezes, this no problem in a metal container if you allow for a bit of flex or on the side added strength  - whatever suits you better. Another option is to get a few different cold packs (by the active ingredient) and to do a check in a little container. Freeze it and note whe level cold and warm. Little to no difference means nothing to worry in terms of expansion during freezing.

Topic by Downunder35m 

How to reduce signal noise in a circuit (for Amplifier)?

I am building a sound reactive RGB light. Using a LM386 and a 16f88's AdC. I got it to work great with just 1 RGB LED on a breadboard, powered from a 7805 I then built it on perfboard, watched the amp's output on my O-Scope, worked fine. this schematic for LM386Once I hooked up 3 Constant current regulators with 3x 3 watt LEDs(red-green-blue) through 3x MOSFETS, the Amp's output signal becomes blurry/chaotic and the light malfunctions. The regulators negative output must be connected to logic GND, which i know to be where the interference is coming from.How can I reduce the noise coming out of the Amp? Even if I gotta use different type of Amp. I don't know to much about them.

Question by PuffMag1cDrag0n   |  last reply

power supply voltage reduction 9v input to two 3v outputs

Hello all ! I'm new to instructables and I’ve found some cool and helpful information for my projects. I need a bit of help designing a power supply voltage reduction device. One that accepts 9v input and output into two 3v 5mA outputs. I want to replace the batteries in a/b Boss selector with a more reliable source of power.

Topic by testpartner   |  last reply

what kind of fabric could i use for headphone foam noise insulation? Answered

still thinking of making custom headphones for fun. would love to make the cushioned pads on headphones but don't know what sort of fabric is could use around the foam. I want something as waterproof/resistant as possible to protect from sweat. really wanted to make square foam inserts and cover them with the fabric for noise reduction. thanks

Question by plasticpopcorn4   |  last reply

Stepdown from 19V to 12V using 3 IC for reduce the heat output?

Hey guys,  I want stepdown my charger laptop from 19V to 12V but I read from they said IC produce excessive heat if I connect it directly, Then does by doing 3 stages of reduction, can reduce the heat output of the IC? For example I use 7818 > 7815 > 7812 for 3 stages of reduction.

Question by goldenyears1x   |  last reply

what is the possibility of having liquid crystal shutter in a camera? Answered

I've seen many camera, they all have mechanical shutter, what is the possibility of having liquid crystal shutter in a camera,like in shutter glasses?

Question by Suraj Grewal   |  last reply

youtube no option for 144p and 480p and 1080p when using tethering on phone [ANSWERED]

When I open youtube to watch any video, and I am connected to the WiFi in the house, I get all the quality options available to me: 144p, 240p, 360p, 480p, 720p, 1080p, and occasionally original (usually reserved for 4K resolutions?) However, when I use my phone's 3G/4G and wirelessly tether that to linux, I do not get all 6-7 quality choices. 144p, 480p, and 1080p are missing. shows tethering 4G to my computer shows a 3-8 Mbps down with ~70ms latency. the WiFi in the house is CenturyLink DSL, and can get as fast as 1.5Mbps with latency ~50ms at best, it can sometimes get very slow and I am forced to switch to tethering my phone's 3G/4G. Also, it is worth noting that the 360p quality appears more compressed, The amount of "boxiness" (MPEG reduction) is annoyingly high. (poor quality) While the phone is in 3G, I can't even watch 720p quality, the lowest quality that allows one to make out a faces in the video. It does not appear to be Chrome, the browser I'm using or flash video, as it is also true with the HTML5 player. 

Question by -max-   |  last reply

anr aviation headset pc conversion

I have an anr (active noise reduction) aviation headset that I want to use with my pc. I've searched everywhere but nothing converts it directly from a six pin LEMO (power panel, redel) to anything my computer will take. I'm assuming because the anr requires a power source. is there anyway I could convert it?

Question by bravoechonovember1   |  last reply

How can I open the earphones of the Sony NWZ S639F mp3 player to replace its cable? Is there a non-destructive way? Answered

These are normal headphones (not those with active noise reduction). I think they are used in many Sony walkmen. The cable is just too tiny -- I want to replace it with a stronger one.

Question by J. Raff   |  last reply

How do resistor-capacitor circuits work? Answered

I know this is a basic question, but it has bugged me, and is in two parts. The first: Are resistors like reduction valves for electricity? i.e. Do they simply absorb and dissipate excess electricity, or do they restrict its flow, as in making a large capacitor discharge its energy through a resistor to prolong output from the capacitor? Also, do capacitors store electricity until it is full, then release it, or is that only when they fail? Thanks!

Question by mad magoo   |  last reply

3.3V to 3V - Power a GameBoy Color from USB

I want to power my GameBoy Color using the USB port. It needs 3V ( 2 AA batteries). I found a voltage regulator, that puts out 3V, but it does not seem to be available in Germany. But there are loads of 3.3V regulators. So I wonder, how I could use one of those. Is it possible to simply put a resistor in row (if yes, what value would be suitable?) or is it a bit more complicated?

Topic by SpecieS~   |  last reply

Power supply volt/amp question?

Hi, My power supply is ac 110v to dc14V 700ma and I want to connect in parallel 2 strips of 4 led (350ma - 3.2v each)  Total voltage per strip 12.8v with 350ma each. I would like to power these leds at 2.5v each (total 10v)  and at around 250ma each. I installed a buck converter at the output of the power supply to reduce voltage at 10v. Will the amps also drop as voltage is reduced or will it stay at 350ma on each strip?  If it does not drop, how could I reduce amps to about 250-275ma? Thanks

Topic by Lion_Heart   |  last reply

Lowering the power coming from wall socket into Wood burner?

Hey hey, I have a wood burning system that I LOVE, but at its lowest setting it burns just a touch too hot. It has a variable temperature dial, but it doesn't go quite low enough for me. Is there a way for me to reduce the power coming into it from the wall?  As an example of the kind of reduction I'm looking for. If I run my small space heater off the same outlet, the wood burner burns slightly cooler at a temperature that works for me. Any help would be extremely helpful! Thank you in Advance! Mike

Question by MichaelW552   |  last reply

Coilgun? Induction? Or something else? Answered

Hi, There video above shows a simple coilgun like device that shoot coins. In my understanding, it looks like a simple induction Coilgun design, since it repel coin away from the coil instead shoot the coin through the middle. However I have a hard time replicate the result. I use the same camera with the same capacitor (350V), and also use penny for the non magnetic projectile. Its the coil part I'm not sure about. In the video, it looks like a relevantly messy and small coil. Can anyone suggest me on the coil design for the same result? Most resources I found are either on reduction design or base on coilgun design instead this simple shooting mechanism. Thanks   

Question by ljfa321   |  last reply

AC 30v 50/60Hz Synchronous Motor from 110

So I bought some Mirrowave turn table motors to use as an Epoxy Rod dryer I knew I didnt want the 220's and thought I had bought 110 AC  but they are  AC 30V    3W   I have 4 of them and need to know a cheap way to wire em up.  Was being cheap and didnt want to pay $10 a motor and got all 4 for $10 but now I see I am going to need a voltage reduction and or transformer.  Was thinking one of my old printer or laptop cubes would work.. but those are all AC/DC converters :-( I am pretty good with hands.. but Electrical circuits not my strong suit. 

Question by ToddG39   |  last reply

Diy Intercom/Two-way with Arduino

Hallo Everybody, Hopefully I am posting this at the right place!? I dont have alot of experience wih arduino, so thats why I am asking here and I hope that someone can help!? The Scenario : My Parents in Law have a very old and very load campervan. They bought themselves each headphones/Headsets with active voice reduction wich helps alot with the noise in the Van but they cant communicate with each other.... The headphones came with a cable sothat you can connect it to a mobile phone with speech function.(Like a Headset for Skype..) Now my quiestion : Is it possible to connect the 2 Headphones/Headsets to something that is mounted stationary (<12V)  in the campervan sothat they can also use the speech function on the cable/Headset to communicate? Would it be able to do with arduino? How? I would appreciate any information! Thank You Ps. Hope my english isint too bad....

Topic by Rudster85   |  last reply

How to decrease power, voltage, and amps coming from a wall socket in your house?

I am making a table top and would like to put LEDs in it. I want to be able to connect them to a variable resistor so it acts like a dimmer switch. I want to be able to run this off of wall power. I do not know how to drop the power, voltage, and amps coming from the wall to the ratings of a variable resistor? I know P=VI and V=IR, but I can't find a resistor with a high enough power rating to decrease wall power. what I would need help with is find a componet or something that greatly decreases the Power; thus decreasing voltage and amprage; to a level that I can run through a variable resistor and to the LEDs.   Yes I know LEDs are supposed to run off of DC, but they do work with AC; they just dont get as bright, which is fine by me.

Question by jkindred   |  last reply

what chemicals aside from bicarb soda are present in pool ph buffer? Answered

Hello i just went to the dump shop and picked up a 4kg bag of bicarb soda as ph buffer for free, and when i got home, i noticed it smelt of ammonia, so i though it might have some ammonium carbonate, so i figured i could get rid of it by adding some water to the ph buffer and then boiling it. however, i have noticed that it turned my hands blue, and although the blue washed off, i am now hazardous as to what else may be in thr ph buffer, although it states sodium bicarbonate is the active ingredient. i plan on dividing it, selling 2kg on my site in 250g batches for $2 each, and the other i plan to use as a sodium source for my sodium reduction cell. i need to know though, what the other chemicals in the pool buffer are so i can state the purity of the ph buffer. also will anything lebeled as "soda ash" be pure sodium carbonate?

Question by oldmanbeefjerky   |  last reply

What excellent examples in CAD of low drag coefficient pickup trucks exist that are available on the internet?

Vehicles have been designed to minimize the aerodynamic drag with notable success. Production candidate vehicles (such as Aptera, Twike, and Honda Insight) achieving drag coefficients of 0.25 down to 0.11. Solar Challenge vehicles have reached 0.07. Nose cone and fastback upper and sealed or faired lower body designs can achieve significant reductions in drag, and are worth attention. I am attempting to optimize a design for pickup trucks and cross-over utility (CUV) vehicles that are based on the same basic chassis design. Can anyone contribute designs, examples, or sources of information on optimized pickup design? BTW, I am simultaneously searching for a safe design that has the vehicle center of gravity at or below the axle height, as it should be to prevent roll-over accidents. Risk of injury and death are significantly higher in pickup trucks and CUVs than cars, and now pickups and CUVs account for more than 50% of new vehicle sales. This tragic fact needs to be reversed with safer design.

Question by rkh986   |  last reply

Portable media build parts question

I'm looking to build a portable gaming and media station but I'm stuck on a couple things and am hoping people here might have some suggestions and/or links. Basically, I bought a large aluminum camera case, big enough to hold a 22" led tv in the lid. I am going to mount the tv in the lid, thinking of just drilling the holes and mounting the tv directly to the lid. Any critiques or problems with that would be nice.Second, I'm going to mount a ps3, a portable media player (think Von Haus) which uses flash drives or portable hard drive via US, and a retropie system. Now where I'm running into trouble is two-fold. One is how to mount the items into the case. Foam would normally work well, but I'm worried about heat reduction, less so for the media player and more for the ps3 and retropie. I'm also worried about having it hardmounted onto the case via glue gun because of any shocks it might get while in transport. I also want to dremel out in the front and the back, and put in ports to be able to connect to an outside source as needed. Basically, I need a number of connectors which mount inside with the port leading out. USB 2/3, HDMI, RCA cable connector (RWY). I can find extension cables, but what I'm more looking for is, say for USB, a male lead on one end to connect to the ps3, and a female lead on the other end which sits inside case but is dremel'ed out to be able to connect a USB from the outside, basically a plate which I can just screw in. Something similar to what you'd find inside a console or similar. Anything which anyone can help with on any of these would be greatly appreciated Thanks...

Topic by Henrryparth 

Portable media build parts question

I'm looking to build a portable gaming and media station but I'm stuck on a couple things and am hoping people here might have some suggestions and/or links. Basically, I bought a large aluminum camera case, big enough to hold a 22" led tv in the lid. I am going to mount the tv in the lid, thinking of just drilling the holes and mounting the tv directly to the lid. Any critiques or problems with that would be nice.Second, I'm going to mount a ps3, a portable media player (think Von Haus) which uses flash drives or portable hard drive via US, and a retropie system. Now where I'm running into trouble is two-fold. One is how to mount the items into the case. Foam would normally work well, but I'm worried about heat reduction, less so for the media player and more for the ps3 and retropie. I'm also worried about having it hardmounted onto the case via glue gun because of any shocks it might get while in transport. I also want to dremel out in the front and the back, and put in ports to be able to connect to an outside source as needed. Basically, I need a number of connectors which mount inside with the port leading out. USB 2/3, HDMI, RCA cable connector (RWY). I can find extension cables, but what I'm more looking for is, say for USB, a male lead on one end to connect to the ps3, and a female lead on the other end which sits inside case but is dremel'ed out to be able to connect a USB from the outside, basically a plate which I can just screw in. Something similar to what you'd find inside a console or similar. Anything which anyone can help with on any of these would be greatly appreciated.

Topic by GeorgeGrace   |  last reply

Does an LED driver rated @ 6v -12v hold/keep a source voltage of 8.4v to 6v or just maintain it between 6v - 12v

I should preface my inquiry with an admission of possessing very limited electronics knowledge. but I am somewhat familiar with battery voltages & amps. I have several Luminus SST-50 & SST-90 LED emitters. I have found that to achieve the full lumen potential these emitters must be driven beyond Luninus's stated typical vf of 3.2 volts. I do not exceed 6vf. I am aware that current is a major factor in the performance of these lights, but when using 5-6amps or the max of 9amps (SST-90)I notice little difference in the brilliance of the light. However, when altering the vf from 3.2v or 4.5v to 6v the difference is amazing. When using 5 X NIMH batteries (= 6volts/4.5amps) with an SST-90 the lumens are high. When I use 4 X NIMH bat @ 4.8 volts/4.5amps, there is about a 25% reduction in light production. With my limited electronics info.I assumed the voltage was the key force here. Or is there something about the volt/current relationships that I need to know? My ? actually concerns the drivers that I have. They are rated @ 6v - 12 v. Do you know if a driver, with these specs, regulates/holds the vf @ 6 volts when the source voltage is greater than 6 volts or does it just maintain the voltage within the range of 6v - 12v. Using 2 X 4.2v LIon batteries, connected to the driver, gives an 8,4v the volt meter reading. Such a voltage will destroy the emitters. I expected a reading of 6vf (@ the driver leads). If you are able to answer my question, one I would be profoundly grateful, 2 please be as detailed/specific/simple as possible. Thank you very much cgc210

Question by cgc210   |  last reply

The use of gas generators in the home.

Available pluses home gas generators: * Rate per se gas generator compared with the price affordable euro GASOLINE. * The price of fuel is lower than that of the generator on diesel or gasoline. Available Cons: * Gas ​​is considered the most volatile than diesel or gasoline. * Appeal from the gas and the installation of equipment for gas processing requests for special and separate permission. Our legislation prohibited the installation of systems and gas processing equipment in the absence of a suitable plan or agreement. * Most of all, on our market, there are gas generators made in China. * Gas ​​generators are made on the basis of a gasoline engine, the method of adjustment of fuel injection system and fuel carburation. In accordance with this resource from the generator corresponds to the resource gasoline engine. * Later, the acquisition of the gas generator of small capacity, the buyer is faced with a specific limitation on work: a maximum of 6 hours per day. The resource identified by the manufacturers of gas generators, with the first glance quite broad. However, do not understand the root cause of its increase. On average, the share of gasoline engine, out of which gas engines, floats in the range up to 2000 HOURS. This common resource for the euro generator. Imagine the Chinese gasoline engine, the resource is constant. Next, suppose that the resource oposlya changing gasoline engine to natural gas will not decrease. (Our real change of cars with fuel gas indicates a reduction of the resource engine, which originally was made for 1-octane gasoline, well, and subsequently applied for another). 1 of firms offering gas generators, a guarantee in 2000, machine hours, or one year, although with the limitation, at least 6 hours per day. The appointment of such a generator is not clear. As a source of constant power, he will not do, as backup - as well as the first blackout since most 6 hours (which happens often) determines the total loss of warranty. It is reasonable to imagine that the buyer, which turned off the light of day, will not sits all day in the absence of light, zhdya coming the next day. In general, in fact, a similar limitation on the work looks pretty amazing: It seems as clear that the miniature generator with cooling air is not able to operate around the clock. While that still causes inconvenience to cool the generator, for example, for 1 hour, and then resume his work? In solid power installed thermal disconnector, which simply will not allow too much power to warm up, and therefore, the decision on mode of operation.

Topic by saylar 

Potentiometer/Variable resistor with AC advice

I'm a computer store tech who knows how to solder some(but DC stuff only) and who also enjoys cooking, so my ? is: What's the best choice of pot. for use with US household current to actually control the cooking temp of my hotplate? End result is to eliminate the annoying "heat spikes" you get due to lack of a pot. in the design, IE literally everything sold these days turns on at full current/temp until it reaches X temp, basically it's just temporally defined by how far you turn the knob, and your pancakes wind up crispy black around the edges and gooey in the middle  instead of golden brown and amazing all over. I want it to turn on at X current until X temp (like electric frypans/burners did if you're old enough to remember.) All I need to do ( I think) is add a pot/VR into my burner's element  "line" the right way, it already shuts off at X temp just fine. Incidentally, that's the "click" you hear when any home electric cooking device (sold in North America, at least) hits temp or turns on, the temp. control switch thingee connecting. It's NOT a VR/pot, just a pair of electrodes JUST barely touching strapped very tightly to some ceramic discs. It uses thermal expansion of the discs/electrodes to make things just a tiny bit bigger and separate the tiny little electrode spoons  But all that boring geekspeek affects in this configuration as basically just temporal heating, IE no reduction of the amount of heat in my frypan, just the cooking time. Science says if I reduce the amount of electrons flowing thru it just slightly as well,  it'll be colder but still hot and still shut off when it's hot enough. A pot/VR wired in the right way will do exactly that, won't it? After some research I'm thinking something like a 30-50K "B"-taper pot. wired with 2 of 3 traces (, I'm looking for a "broad" response range while turning with a tight  "pinch" effect at low end for amazing banana-brown-sugar-pinch-of-nutmeg pancakes with coffee on the tiny balcony/fire escape in the morning but I have no idea how the numbers work for AC currents. Does 120vAC mean a different pot or a diff config/approach altogether? Or should I be looking into AC variable resistors, instead? I know an awful lot about "base" science, enough to get me this far, right, but AC throws me for a loop a lot, and there's a gap in my knowledge/experience, between the basic stuff and how it applies to stuff like my application, I don't get a lot of the numbers/formulas and how to use them.  A VR would the ideal tool here, but they are hard to get in the right form with the electrical qualities I need, whereas pots are usually "turning switches", right?

Topic by MattH68   |  last reply

What is the axial orientation of Polaris with respect to the Earth? Answered

So... I know the Earth's axis of rotation currently points (roughly) at Polaris, the North Star. (which, of course, is why we can navigate by it here on Terra Firma).  I also know that Polaris is about ~500 ly from us,  has a rotational period (hence an axis), that it's a transitional Cepheid (sp) (a star that varies between a larger, brighter state and a smaller, denser one) , that it has at least two l known, low-output companion stars, and that since the ~1940s it has undergone visible changes in its rotational period and its output. My excuse and reason  for asking... First, I did google it. Either no one has asked the question(doubtful), it can't really be determined with our present level of science (could be, idk), or I just didn't use the right search  terms to find the answer (the usual culprit ime) , but in any case, after an off and on search that's spanned the past ~year, I think it's time I ask. Secondly, the inspiration. I enjoy amateur astronomy.  However, time and equipment and location often limit my grand delusions for the next "Citizen challenges Hubble with stunning new photo of Zeta p3044-a!" award hahahaha.  But the real problem is most often because of my mid-level scope's somewhat limited ability (in comparison to a German equatorial mount) to track consistently and smoothly, and as a result, Polaris becomes an easy target when I get frustrated with the scopes performance on a given night (sometimes it does track brilliantly... for a stepper-driven alt-z, but only sometimes and even then only to the limits of the steps) because the only thing the scope has to track when pointed at the North Star is rotation, which it seems to handle better than both directions of movement (probably needs a new gear or the motor is wearing or my expectations are simply higher than that of my equipment ...). Of course, I also quite often choose to shoot Polaris when conditions are such that it's the only viable target (for instance, when I'm stuck imaging from my backyard, I have a postage stamp size hole that happens to point at Polaris... which of course basically "doesn't move", pretty much everything else is shrouded by century old, 8-100 ft tall forest during the warmer months, and when I can't drive out to a more suitable location, it's a lucky night when everything is "right", I can even align the mount (it uses a goto controller that requires a 3 star alignment for tracking with any accuracy). So Polaris is a no-brainer, (take some images for arts sake, fine tune the in-situ collimation, data-reduction test sets, etc.) . Either that or do something else...  Anyway, as a result of all of this, I'm found myself enjoying the simplicity of shooting the North Star and the area around it, and having fun with image processing and even optical train modifications to further the artistic side. And I've read a few articles about it's variability and the ~relatively significant changes in its behavior that have been occurring during the past 50 years that got me to thinking What I'm wondering is that when I image Polaris, am I looking at it "on its side?", "on axis?", or at some other viewing angle? Not that I'm going to be able to literally "view it on its side" or something, since optically imaging the star beyond that roughly of a point-source isn't practical, but just to know, since the darned question won't get out of my head. (been asking it for the past year quietly to myself and google. I hate to think how many cumulative hours I've spent at it...) thanks!

Question by seandogue   |  last reply

How to make Flip Clock Numbers and build a "like"-counter around it?

Hey All So I've got this client, who's absolutely crazy about the "FLIKE" (A physical like counter.). But he can't have it for another couple of months, and he'd like it to be a little more custom... Long story short, I might end up making a similar product in a few weeks. it will probably consist out of 5 digits and if it's up to me (not sure what the client wants) I'd stuff them behind a long picture frame. Something like this but actually mechanical and not just a picture of it: So I started googling every hardware piece I needed and it turns out it's a huge pain to find Flip Clock Numbers / Flip Board Numbers... whatever you want to call them. (What's the right name btw?) You can't just buy these things, let alone in a custom size. So the idea is to build them myself. I found this on wikipedia, which gives a clue about the inside: So I'm figuring out what needs to go in it to make this work. (I'll end up making an instructable about it) The numbers themselves are going to be made out of vinyl stickers. You can easily buy those from ebay in about any size if you look for them. The stickers will be put on to plastic boards. But I'm not totally sure what kind I should get. They should be thin and must be able to stand up straight, yet "easy" to fold. I'll probably get them lasercut, but you should be able to cut them by hand as well. Currently I'm thinking about gluing small metal or carbon rods on the back of those letters. Although I'm not sure if that would be strong enough. Would it be enough to file one side of the rods to get a bigger contact surface? (What do you guys think?) I'm planning of putting the half letters in a drum of ABS or PLA. it should be shaped like this:  |--------| I'm thinking about 3D printing this. But no idea how it'll do... One side of the drum will be connected to a small stepper motor (5.625° with 1/64 reduction). I don't have real experience with stepper motors, but this resolution seems more than sufficient. The other side will be connected to a metal or plastic positioner. Each digit might end up with it's own "unit" so I can swap them separately if they'd break. I've got great experience with lasercut plexi, so I might use that because it's more accurate than wood and I might have some lying around. I was first thinking about 1 stepper motor and a set of gears. I decided not to do that in the end because I don't have good experience with making gears and I can never find the right sizes online. Also, it'll make everything way more complex. So each motor will have it's own controller connected to it. Those controllers would have to talk to an ATMega or something. (I'm planning on using an arduino to prototype, but then just swap the chip and make a stand-alone version without usb etc) The ATMega has to be connected to the internet of course to get the current number of likes, so I'd connect it to a raspberry pi via I²C. I'm not familiar with the GPIO pins on the pi so I figured this would be a save and convenient way to handle this. The ATMega is robust, and I love the Arduino bootloader. A sketch is written in no time, but I have no idea how to start writhing this code for the GPIO pins. So why the Raspberry Pi? First off, this thing might end up being wireless, and since a wifi module for the arduino costs as much as a Pi, I figured this would be easier. The plan is to make the pi run python script that could ask the number of likes from the facebook API. Once returned, it'll send +1 or +5 or +10 over I²C. The arduino shifts the numbers to the correct position and replies with the total number it's displaying (3012 for instance). The PI can then recheck if everything is in sync. As for the set up. Since we have Pi, we can put on a LAMP stack (I know, this is overkill, but it wouldn't hurt either). So for initial set-up, we'd connect the counter to ethernet, browse to it on a different computer via "http://counter.local". And we'd be presented with a web interface. You'll be able to set the URL of the page u want to get the likes from, set and reset the number that is displayed on the counter, and the WIFI settings. The WIFI settings can be saved in the wpa_supplicant.conf file and on reboot it'll automatically connect to this network. From now on the whole system is manageable over wifi via a html interface. For debugging I might enable ssh though. So I guess you've got the whole outline now. I'd like to get your feedback on this! And this for the mechanics, electronics, and software side of things! 

Question by woutervddn   |  last reply

How much Mercury is in Compact Fluorescent (CFL) bulbs, watch batteries, and coal-fired power plants?

In Brennn10's Compact Fluorescent Instructable there was a short discussion about the amount of mercury contained in CFL bulbs. The same topic came up in a mailing list I read, and there was some interesting analysis worth sharing.Statement:The Stranger (the Seattle weekly) has a column called "Dear Science" where the typically quite intelligent author argued that CFL bulbs weren't all that "better" for the environment because inevitable improper disposal put more mercury-n-shit into the environment. So unless you got all your power from a mercury spewing coal plant, you shouldn't use CFL's . And Seattle, getting a majority of it's power from hydro, shouldn't use CFL's.This was called into question for being selective analysis that encourages an attitude of "there's not currently a solution, so keep doing what you're doing", and elicited the following response:Just so I can bore everyone with what I think is the current level of knowledge about mercury and CFLs, here's some of the current information.NRCan did a study on how much mercury is actually in CFLs, and compares them to other typical consumer sources (e.g., watch batteries--if you throw one of them out, you've throw out five times as much mercury as in a CFL): reading this, I actually worked out these numbers for myself on how CFL savings compare to mercury releases a few months ago. Of course, this is all more environmental destruction brand X vs. brand Y discussion that was being talking about.I was curious about what the numbers work out to, so I went to dig for some data; this is what I came up with.In 1999, about 1.75 trillion kWh were generated by coalEnergy Information Administration Annual Energy Review 1999, Figure 26In 1999, 47.8 tons/year of mercury emissions came out of coal-fired power plants.Source: U.S. EPA, Office of Air Quality Planning and Standards.1999 National Emissions Inventory for Hazardous Air Pollutants. calcs out to a figure of 0.025 mg mercury per kWhAssuming 5 mg mercury per CFL, the equivalence point is about 200 kWh--a CFL would need to save 200 kWh before getting tossed in the trash. A quick calculation shows that this is about how much a CFL saves in half a year, if it were run 24-7: 75 W for an incandescent; 25 W for an equivalent CFL = 657 vs. 219 kWh/year, or 438 kWh/year difference.Of course, this assumes that the coal mercury emission rate is the same as it was in 1999; I'm not sure if measures have been taken since then to reduce mercury emissions. Also, this is assuming that 100% of the power saved by the CFL would be generated by coal-fired power plants. But even with that assumption, coal is such a large fraction of the power generation (typically about half)--it would jump from six months to a year, instead. Of course, this period gets longer assuming a realistic duty cycle, but still, those numbers all seem to pencil in below typical installed lifetimes of CFLs.Finally, there's a article from Home Energy magazine (behind a subscriber link), where somebody did a similar calculation with more current numbers, I think.;_title=Understanding_CFLsHome Energy MagazineNovember/December 2007Understanding CFLsby Richard Benware"Although the use of CFLs is steadily spreading, public understanding about how to dispose of them responsibly has not kept pace."Life Cycle BenefitsIn order to disprove the myths about CFLs, let's begin at the beginning. When CFLs are created, manufacturers dose the bulb with a small amount of mercury. This mercury, when electrically stimulated, releases UV light, which subsequently reacts with a phosphor coating to create visible light. Thus mercury is an essential part of every CFL; without it, the bulbs would not produce light. The typical dose of mercury is about the size of a pen tip, and these doses have been getting smaller and smaller. One reason for this is that the laws resulting from the Restriction of Hazardous Substances (RoHS) Directive have made it illegal for CFLs in Europe to contain more than 5 milligrams (mg) of mercury.In the United States, there are no such laws limiting the amount of mercury in lightbulbs as yet, but members of the National Electrical Manufacturers Association (NEMA) have voluntarily agreed to limit the amount of mercury in the CFLs that they produce to 5 mg for bulbs of up to 25 watts and 6 mg for bulbs of 25 to 40 watts. The average CFL on store shelves today contains about 4 mg of mercury, and nearly all the CFLs in production contain less than 5 mg. The mercury used in all the CFLs produced in the United States represents 0.18% of the mercury used in all U.S. products andindustrial processes.CFLs do not release mercury as long as they are intact. In fact, they reduce net mercury emissions in the environment by conserving energy. For every kWh of electricity used by consumers, the average power plant emits over 1.5 lb of pollutants. If a 75W incandescent is replaced by an 18W CFL, the CFL will use 456 kWh less energy than the incandescent over its 8,000 hour lifetime. The Emissions and Generation Resource Integrated Database (eGRID) contains data on the emissions of the average power plant. Using eGRID's information to calculate the average emissions per kWh, we find that this single CFL has prevented the release of 2.72 lb of sulfur dioxide, 1.05 lb of nitrogen oxide, 5.67 mg of mercury, and over 700 lb of CO2.It is important to note that these are the reductions from the average U.S. power plant. The eGRID data show that, on average, nonbaseload emissions tend to be dirtier. And in addition to reducing emissions, CFLs save money for the consumer. The Energy Information Administration (EIA) gives a 2006 average residential electricity cost of $.1008/kWh. Using the example given above, and basing our calculation on this figure, we find that a consumer would save about $46 on energy over the lifetime of the CFL.When these bulbs finally do reach the end of their useful life, there are several pathways they can take. In the best-case scenario, the bulbs are recycled. Recycling rates are increasing, thanks to state regulations -- California and Minnesota have banned altogether throwing CFLs in the trash -- and improved consumer awareness. In 1999, it was estimated that only 15% of all fluorescent lightbulbs were recycled. Currently, that number has increased to around 25%, with higher levels in commercial applications. Since an average of 98.9% of the mercury is successfully recovered in the recycling process, this pathway generates minimal emissions.Even the CFLs that are discarded in the trash are unlikely to release much of their mercury. Although most of them break under current trash disposal methods, some remain unbroken, and will not release any mercury. But those that do break are not likely to release much mercury. EPA estimates that only 0.2% of the remaining mercury in a spent bulb is elemental vapor. The rest of the mercury is in the glass, the phosphor coating, and the electrodes of the bulb. Mercury absorbed in these areas is not readily released. In fact, an EPA study found that only 6.8% of the total mercury in a broken bulb will be released. Since the average bulb on the market today contains only 4 mg of mercury, it will release only about 0.27 mg, even if it breaks when it is thrown in the trash.The only disposal option that could lead to the release of any significant amount of mercury is incineration. Today, many incinerators have advanced mercury control technologies. CFLs disposed of in such incinerators would release up to 90% of their mercury, but those emissions would then be removed by these technologies. Incinerators without these technologies are not capable of removing the mercury. But even after accounting for all of the emissions that occur via all of the routes listed above, CFLs represent a mere 0.01% of total U.S. mercury emissions annually.It is important to note that even if CFLs released all of their mercury, the environment would still be better off than it would be if nobody used CFLs. This is true because the average power plant releases 5.67 mg of mercury to power each 75W incandescent bulb. In short, replacing incandescents with CFLs is a great way to save energy, reduce mercury emissions, and save money (see "Discounting CFLs").

Topic by ewilhelm   |  last reply