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  • Arduino-controlled True Switching Regulators

    sticking a 1Meg Ohm resistor at the comp pin and adding a note that using a different value may be ok.... no it is not ok! you already knew that it did not work but u went ahead and published it. why did u do this? for the contest?

    read above

    MartinD; I'm sorry for being so harsh in my comment. I thought u were just posting to win the contest. Now as for Loop Comp... No u do not have any and perhaps u should read a little about what it is and what it means. then you will know that I am saying is the truth and not trying to be mean to you. it is much too involved to explain online like this. if it was simple I would try. and it has nothing to do with the TL494. it has to do with the fact that u have an LC filter at the output and u are feeding back to the controller (TL494 or any other). an LC filter is a 2 pole filter and one pole needs to be cancelled and you don't have it anywhere in ur schematic. the op-amps, etc. that u mention do not make compensation. what u have there are merely sensors and they only close ...see more »MartinD; I'm sorry for being so harsh in my comment. I thought u were just posting to win the contest. Now as for Loop Comp... No u do not have any and perhaps u should read a little about what it is and what it means. then you will know that I am saying is the truth and not trying to be mean to you. it is much too involved to explain online like this. if it was simple I would try. and it has nothing to do with the TL494. it has to do with the fact that u have an LC filter at the output and u are feeding back to the controller (TL494 or any other). an LC filter is a 2 pole filter and one pole needs to be cancelled and you don't have it anywhere in ur schematic. the op-amps, etc. that u mention do not make compensation. what u have there are merely sensors and they only close the feedback loop without the Loop Comp.The schematic in the datasheet is incomplete in that they do not show the Loop Comp components. they only mention it when they are suggesting a layout. it was written in 1983 and at that time loop comp was not very well understood by a lot of engineers so it was omitted from the schematic in the datasheet. if u look at some modern day datasheets or app notes you should see the components and design notes of how to do it.

    it is a power supply. you supply the input power and it supplies regulated voltage at a different voltage based upon the command that you give it, even if your input power supply voltage changes. he has shown three different outputs relative to the input voltage. one gives a higher output another makes a lower voltage and the third gives a negative voltage. The schematic does not show where the input commands come from. Also he does not show the Arduino code. it looks like a good design but i have not analyzed the closed loop control so who knows?

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  • JohnC430 commented on zposner's instructable The Digital Doormat3 days ago
    The Digital Doormat

    Now all u need to add is a high voltage source and zap the intruder

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  • Reclaimed Oak Trestle Table

    WOW!!! again WOW!!!! very nice

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  • JohnC430 commented on m8pilon's instructable Wood lamp 2 weeks ago
    Wood lamp

    Very nice. Congratulations.

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  • JohnC430 commented on kasra_sa's instructable Brush-less motors for your drone3 weeks ago
    Brush-less motors for your drone

    kasra_sa. thanks for sharing such a good instructible. very good info. Thin wires are only needed because it is difficult to bend thick wires when winding. Electrically it is only needed when running at 20KHz or greater and BLDC only runs below 5KHz.

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  • JohnC430 commented on ShakeTheFuture's instructable Make a Melting Spoon3 weeks ago
    Make a Melting Spoon

    cooool !!!!!! thanks for sharing

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  • JohnC430 commented on makjosher's instructable Rocket Boat1 month ago
    Rocket Boat

    is there a way to make slower burning fuel?

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  • JohnC430 commented on souhadl's instructable Motion Detection Lights 1 month ago
    Motion Detection Lights

    i was obviously just kidding about going back to school.

    he means that if there is a short from 230V to the pir sensor. the power supply is a commercial product with Isolation and beyond that there is only low voltage so I don't see how that can happen.

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  • JohnC430 commented on souhadl's instructable Motion Detection Lights 1 month ago
    Motion Detection Lights

    oh by the way now taking JodyF's "advice". I think it is time for you to go back to college and get your engineering degree. I am an electrical engineer and also am a certified electrician and have designed and built dozens of high power and high voltage electrical and power electronics projects. I understand what he is talking about. he is right about safety, however since the project is already in a safe place and out of reach, there is no need to off the deep end.

    check ebay and understand what a PIR detector is. too bad about your nightmares

    for the next one use a 220ac/12VDC regulated power supply and add the 5V regulator. LM7805. you do not need much power for this project and everything will be safe.

    Don't pay attention to the negative comments from JodyF. you did a great job of this and installed it where hands do not normally go. so "stray wires" etc is nonsense. it has already been installed.

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  • Designing a Dual 40A PWM Speed Controller for Brushed Motors

    Thanks. The output waveform of "Modified sine wave" inverters is like that and I wondered how you did it. I know it must be easy but I'm still trying to figure out how to do it.Have you tested it yet on the motors using batteries?

    Hi nqtronix. you mentioned a "push-pull" what is that? I am not familiar with that. please explain/describe it. Thanks.

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  • Designing a Dual 40A PWM Speed Controller for Brushed Motors

    I'm glad you finished. Congratulations!! I need an explanation about Step 22. the scope waveform shows a positive going waveform "Full ON" and then at 50% on a series of pulses in the positive and then another series going negative. what were your measuring points? where did you attach the scope ground?

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  • JohnC430 commented on pascal_stv's instructable Upgrade Led Flashlight for fun1 month ago
    Upgrade Led Flashlight for fun

    don't worry about your English. Half the English or Americans don't speak better than you. in this article it is your technical knowledge that is important which is not lacking.

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  • JohnC430 commented on smart_coaster's instructable DIY Smart coaster1 month ago
    DIY Smart coaster

    WOW! over $100 for a coaster? Hmmmmm... Classy restaurants will not use these. the mid level ones will balk at the price. destroying a $25 scale to pull out the load cell... only done by college students who have no concept of economics. Not even a proper schematic and the only drawing of the Wheatstone bridge was an almost illegible scribble on a piece of paper. why such a bad presentation? is this what comes out of KTH Royal Inst of Tech? sorry for the bad critique. the product is innovative and interesting but is it practical? its ok to have it in ones home or give one as a gift. It would probably be a product to sell at "The Sharper Image"

    Glasses come in all sizes and shapes and weights. the restaurant will need to calibrate each type of glass they use and build a Table. then we come to a situation that two glasses will be the same weight when empty but will differ considerably when partially full. then what happens? This is not a "product" for mass use. it is ok for individual use. This has not been fully thought thru. sorry for being so critical. I am an engineer who designed for small quantity as well as for mass production and see "holes" in some designs. this critique is not to belittle but to try and help. I am sure that solutions can be found for my questions.

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  • 1$ Wireless Speaker That Connect's in 0.0000000001 Seconds !

    Kedar, why not also show a schematic? all those pics do not help without that.

    Guys!!! don't focus on the number of 000 he put there. he obviously just threw them in to emphasize that the "delay" would be minimal.

    in the pics he has a HUGE coil. You can make the coil with 100 Turns #30 AWG wound around the end of a pencil. Teeeny weeeny.. and it will work just as good.

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  • Set of Broadheads Made From an Old Saw Blade

    why did you make the holes in them? after all you tied the head to the shaft.

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  • JohnC430 commented on Instructa-Nathan's instructable No Nonsense Survival Kit1 month ago
    No Nonsense Survival Kit

    Good thinking!

    more great ideas

    Great instructable. Thanks for sharing. Why not also include a few small sachets of Neosporin?

    more great ideas! thanks. gonna make a list of everything and fill a few small kids back packs or lunch boxes and put them in places where they will be accessible. Although the idea behind the Altoids box is to have a small "safety pack" always available. but where? I am not going to keep in my pant pocket and carry it around with me wherever I go. so I guess one in the car(?). I lived in Northridge during the Northridge earthquake. the situation was pretty grim, but I had a pool so I used pool water and a kettle and put it on the barbecue so we had coffee and we cooked on it too.

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  • JohnC430 commented on anil8tor's instructable Solar Heater for My Shop1 month ago
    Solar Heater for My Shop

    well, he already took measurements and it shows about 17 Deg Celsius in crease in Temp. does that not show that his 20 Gal tank is working? After all he is only heating his shop. On the other hand what did you mean when u said " will have 15% reduction in heat transfer"? I thought the idea is to get maximum heat transfer from the dish to his shop. I agree Glycol is better than water and will keep the tubes from freezing and will also prevent oxidation of the tank. True 50% solution is good for -25C as it says on the Glycol jog.

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  • JohnC430 commented on ClairisaS's instructable How to fix separated nylon zipper teeth1 month ago
    How to fix separated nylon zipper teeth

    I have a jacket with almost exactly that problem. I guess I have to show this article to my wife so she can fix it.

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  • Measure The Moisture Content Of Your Firewood With A Multimeter

    wood species is not relevant when measuring moisture. you are measuring moisture in anything... your flower bed.... or your hand...

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  • Building Plyometric Boxes (Plyo Boxes)

    Thanks for sharing this project. it looks great.I cant find the thickness of your plywood sheet. I would like to make one of these. I'm short and have difficulty reaching the shelves in the pantry and I think one of these will help. of course I can go out and buy a small 2 step ladder, but where is the fun in that? this will probably cost me an arm and a leg in comparison, but I want to make one.

    3.879 = 3 3/8" How? 3.879 is almost 4". Soooo? what's with that iPhone app?

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  • Designing a Dual 40A PWM Speed Controller for Brushed Motors

    what does it look like when you connect the motor?

    Yes I agree about the Zener diode not required in this circuit. voltages are too low.

    I thought you were aiming for 40 Amps. 3 Amp resistive loads don't simulate a 40 Amp motor drive.

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  • Floating Ghost!!! Low Cost Easy to Make!!!!

    Looks great!! Thanks for sharing.where do you buy cheese cloth?

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  • Designing a Dual 40A PWM Speed Controller for Brushed Motors

    are u looking at the fan wires?

    one simple way to look at gate drive is to try and make the driver with fast edges and to pump the Cgs with 1 Amp during turn on and off. this pulse lasts approx. 200nS so its two pulses per gate drive pulse. 1 Amp seems like a lot, but the average current works out to be only 20mA at approx. 100KHz so it does not burden your Aux supply.

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  • JohnC430 commented on Kester1's instructable 18650 Battery Charger1 month ago
    18650 Battery Charger

    why put them in parallel when eventually u are going to charge each battery individually. He did it correctly. no need for balancing since they are being charged individually.

    yeah, I agree.

    "A 4x18650 powerbank" what does that mean? and whats the significance of that remark? i did not understand. please explain. Thanks.

    RobnAus 6 hours ago This instructable is as lame as your huge begging for a tiny you tube channel. I won't repeat what others have said but taking a few off the shelf boards and giving us instructions on how to tape them to a piece of wood is embarrassing.I agree with RobnAus what you did is not nice. well maybe he said it a little more forcefully than I would have, but he conveyed the sentiment quite well.

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  • L293D Motor Direction Control for under $2.20

    yeah or u can also try just spinning the motor by hand!! lol sorry for my sense of humus.

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  • Designing a Dual 40A PWM Speed Controller for Brushed Motors

    by the way, the 10K resistors across G/S is to prevent the gate from picking up some stray charge and "floating". they are not turn off resistors. In the picture you have some diodes adjacent to each transistor. I guess they are the 1N5822. as for the capacitance of a TVS or a Zener across the Gate, it is insignificant compared to the Miller Capacitance so don't worry about adding it. it will protect your Gates from spikes.

    did not survive because of the 10K resistor across G/S or because you had over 20VDC as your input power or both. 10K causes a very slow turn-off (nothing to pull down the gate) and if you turned on the other transistor in the leg while this is still turning off then boom! since you had such a large input power supply. You need a small "dead-time" between one Q turning off and the other turning on. Makes your circuit a little more complex, but at 40 Amps motor drive this is already a power project and you need safety on everything. In fact look for other ways to drive the Gates so they switch FAST and not with just resistors which are absolutely not a fast solution. I would look for a way to use an NPN-PNP totem pole as the gate driver. Limit the Totem pole voltage to b...see more »did not survive because of the 10K resistor across G/S or because you had over 20VDC as your input power or both. 10K causes a very slow turn-off (nothing to pull down the gate) and if you turned on the other transistor in the leg while this is still turning off then boom! since you had such a large input power supply. You need a small "dead-time" between one Q turning off and the other turning on. Makes your circuit a little more complex, but at 40 Amps motor drive this is already a power project and you need safety on everything. In fact look for other ways to drive the Gates so they switch FAST and not with just resistors which are absolutely not a fast solution. I would look for a way to use an NPN-PNP totem pole as the gate driver. Limit the Totem pole voltage to between 12 and 15 Volts. Read about driving MOSFET's fast. no need to go crazy on that but just get the concept of gate drivers. sorry that I am being so bold as to make these suggestions, but I am only trying to help since you have already done so much and so well.

    well, already you have a 10K resistor. how can the capacitance of the zener be worse? almost every good engineering design has either a TVS or a Zener diode across gate/source. how much is the Zener capacitance compared to Cgs when the transistor is being turned on? insignificant!!!i made the suggestion and you don't have to take it, however research the suggestion and if it is useless then discard it. Anyway, i think you did a great job of step by step building your design. Thanks for sharing.

    I misunderstood when I read "The speed controller in this project did not survive" i thought u were referring to the one in this instructable.

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  • Extensão elétrica útil e prática- Useful and practical extension outlet

    Very strong. Very heavy. Very good! Thanks for sharing

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  • Designing a Dual 40A PWM Speed Controller for Brushed Motors

    Good design. I have been in the power electronics for many years. perhaps the comments by "nqtronix" about gate drive is valid. you are pulling up the gate of e.g. Q1 with very little series resistance and yet the pull down on it is 10K. that not good. similarly for the other transistors. Since the gates/source is limited to Abs Max 20 Volts, that limits the input voltage (by the way you have VCC = 24V). A series resistor between Q6 collector and Q1 gate would allow you to add a 15V zener diode across Q1 gate/source. and doing this to all 4 transistors. This will not limit the input power voltage to less than 20 Volts. Apart from that your whole presentation is wonderful. Thanks for sharing.

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  • JohnC430 commented on tanner_tech's instructable Simplest Geiger Counter2 months ago
    Simplest Geiger Counter

    Thanks for sharing. You did an excellent job of describing the circuit as well as the way you presented it in the Intractable. Instead of the "Geiger" tube could you have used a simple neon lamp of the type used by electricians for testing high voltage in the mains and perhaps using 100 Volts to bias the lamp?

    he is trying to get high voltage hence the voltage doubler. if you're getting an "annoying" high pitched whine then increase the frequency of the LM555. he did everything right.

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  • JohnC430 commented on groovymama's instructable How To Get "Free" Eggs2 months ago
    How To Get "Free" Eggs

    I enjoyed reading the description and instructions. you have a flair for writing. very witty and enjoyable. I would love to do this but I live in an area where we have coyotes and raccoons. I would have to build a fortress to keep them safe. ;). Thanks for sharing. so how long before u got ur first eggs?

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  • L239D Motor Direction Control for Under $2.20

    because the AC goes thru Zero volts and DC can be full on when u try to change direction so opening a switch is bad news for the driver.

    Looks like I missed the schematic somewhere???? Did I?

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  • JohnC430 commented on Victor805's instructable Itty bitty Joule Thief3 months ago
    Itty bitty Joule Thief

    what was the frequency of operation?

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  • Dining Room Table from Reclaimed Wall Studs

    sorry for my negative comment. u did a great job on it. I also enjoy wood working which is why I opened ur link. thanks for sharing

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  • JohnC430 commented on marcus2015's instructable Make your own lye3 months ago
    Make your own lye

    yeah right! with all your paranoid way of thinking about "pesticides" in soap. are u also a vegan?

    step 4 first pic shows the "baby finger" of his left hand. so no missing fingers.

    well why dont you enlighten us with your method instead of hurting the guys feelings?

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  • JohnC430 commented on liwanag's instructable How to build a SOLAR BOTTLE BULB3 months ago
    How to build a SOLAR BOTTLE BULB

    they don't use expensive adhesives. they use what ever they can find. after all they know they are trying to make it "on the cheap". the bleach is not at all toxic. anyone worrying about the toxicity of the small amount of bleach is totally exaggerating.

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  • Dining Room Table from Reclaimed Wall Studs

    Chairs are very expensive but i did not see that in your post. You did a great job of the table top, but you could have bought for a small cost.If u were not working it is a great idea. if you are working how much is your time worth? if it was quick and easy I'd say yeah ok but this tabletop took the life out of you. at that point i would say it was not worth the effort. i know anyone reading this will start haranguing me for this post but sorry that is my frank opinion.

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  • Overview of Quadcopter Components / How to Select Parts

    thanks a lot. very well written and explained. very helpful.

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  • JohnC430 commented on LukaK19's instructable LED Persistance of vision Globe3 months ago
    LED Persistance of vision Globe

    Luka!!!!!!!!!!!!! wonderful job. thanks for sharing

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  • JohnC430 commented on tom4zs's instructable Bike wheel induction safety light4 months ago
    Bike wheel induction safety light

    why did u give us that link? it goes to a company making phones. why add spam in the instructables?

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