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  • LUMOS: Smart Lamp for Better Sleep

    Thank you for your reply..Just to point out, my "risky" was not about breaking the MOS (the Vgs max is 20V, so no risk on this side), but on the fact that you may not be able to fully turn it on. Ok, now you have only 2.5m of leds, and I think this equates to roughly 0.5A of current, but then why choose a 75A MOS? Moreover look at figure 1 on the datasheet: look at the differences between 5V and 4.5V to understand how features degrade quickly when near the Vgsth value; then consider these are the typical values (what is typical between 2 and 4V of Vgsth?). Personally, I'd think of using even a smaller MOS (with Id-max between 2 and 20A) but with a lower Vgs-th, to be sure to fully turn it on with 5V or 3.3V.On the other side, ok for the RSSI; but then I think the arduino is su...

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    Thank you for your reply..Just to point out, my "risky" was not about breaking the MOS (the Vgs max is 20V, so no risk on this side), but on the fact that you may not be able to fully turn it on. Ok, now you have only 2.5m of leds, and I think this equates to roughly 0.5A of current, but then why choose a 75A MOS? Moreover look at figure 1 on the datasheet: look at the differences between 5V and 4.5V to understand how features degrade quickly when near the Vgsth value; then consider these are the typical values (what is typical between 2 and 4V of Vgsth?). Personally, I'd think of using even a smaller MOS (with Id-max between 2 and 20A) but with a lower Vgs-th, to be sure to fully turn it on with 5V or 3.3V.On the other side, ok for the RSSI; but then I think the arduino is superfluous. You are NOT using a DAC peripheral on the arduino, simply because there are no DACs on arduino. And moreover a DAC will not work correctly with your setup. What you are using is creating three PWM waves (you can see this with an oscilloscope on the arduino outputs: a DAC creates a steady DC voltage, while a PWM is a square wave and the ducy cycle is adjusted so that the average value is equal to the steady voltage); the rPI is capable of generating this voltage on his own.My personal suggestions are- if you want to change the MOS, choose one with a Vgs-th max of about 1V; this will enable you to use it directly with the rPI- if you don't want to change the MOS, put another stage in between, to power it with the 12V. For instance, put an NPN (or a small nMOS with Vgs-th low) with base towards the rPI, emitter to gound, emitter connected to +12 through a pull-up transistor and the gate of the MOS. This way you will be able to fully turn the IRF on and make performances better.Just a quick search on RS showed that the IRF1404 costs about 2.4€ each; if you change it with a SOT-23 packaged MOS (SMD mount, so smaller circuit - but they are easy to solder also on a perfboard) I found the FDN337N (2.2A of max Id, 30V Vds max, 1V Vgs-th max, 0.24€ each). If you want to stich with through-hole devices, the IRL2703 is in TO-220 case (24A Id max, 30V Vds max, 1V Vgs-th max, 0.98€ each). Again, this is a very quick search on RS; other suppliers will have lots of other devices, with different prices and characteristics. Just pick your favourite ;)

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  • LUMOS: Smart Lamp for Better Sleep

    I see three major flaws in your electronic design (I assume you are using IRF1404, since I could not find any IRF1504)* The MOS is not a logic level one; with a Vth of at most 4V it is risky to use 5V to power it...* Usually it is much better to put a resistor (about 200 Ohm) between any logic pin and the gate of the MOS, because at turn on a high current can flow* Using a rPI and an Arduino is totally overkill. I did not dig into the "machine learning" part, but if it is simple enough to be implemented on a microcontroller (e.g. by tracking the time when the user puts the phone nearby) then you can move it to an arduino (maybe with an HC-05 for the bluetooth). If it isn't, you can directly power the MOS from the rPI (of course, you need a logic level MOS - with a Vgs-th much ...

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    I see three major flaws in your electronic design (I assume you are using IRF1404, since I could not find any IRF1504)* The MOS is not a logic level one; with a Vth of at most 4V it is risky to use 5V to power it...* Usually it is much better to put a resistor (about 200 Ohm) between any logic pin and the gate of the MOS, because at turn on a high current can flow* Using a rPI and an Arduino is totally overkill. I did not dig into the "machine learning" part, but if it is simple enough to be implemented on a microcontroller (e.g. by tracking the time when the user puts the phone nearby) then you can move it to an arduino (maybe with an HC-05 for the bluetooth). If it isn't, you can directly power the MOS from the rPI (of course, you need a logic level MOS - with a Vgs-th much lower). But.. Don't use another complete board just to avoid using a board properlyBest regards ;)

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  • frarugi87 commented on abzza's instructable Ultimate DIY Breadboard Power Supply6 days ago
    Ultimate DIY Breadboard Power Supply

    A few comments.1) using 6 dip switches here can be, IMHO, a problem. You can leave two of them on (then what is the voltage you will have?), or you can open the connected one, maybe to switch the voltage, thus putting the output to 10+ volts, which may fry the board. Maybe it was better to put a switch also on the output..2) you made a board that could arrive to two lanes. Why didn't you make this dual channel? It is much better to have two power supplies...

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  • frarugi87 commented on MartijnS8's instructable Lamp Base Socket1 week ago
    Lamp Base Socket

    In fact, LED lamps are always less than 10W (see that tiny wire inside), so personally I'd avoid powering anything more power hungry than a phone charger. Which makes me say: why do you (=the author) put a 230V socket instead of directly the USB charger?

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  • Add Email Notifications to Any Robotic Vacuum Cleaning Robot

    Just my 2 cents to give you more ideas for the further development1) I'm experimenting with the Telegram Bot library and.. Maybe receiving a notification on your mobile and not the e-mail can be better, even because it is interactive, and it enables 2:2) you can make the arduino "control" the roomba, maybe. I know that some (or all?) of them have an interface to get commands (a serial one? an IR?).. Maybe you can also trigger the start of the vacuuming, get the battery status, .... ?Anyway thank you for this project :)

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  • frarugi87 commented on HardiqV's instructable Amazing ARDUINO Killer3 weeks ago
    Amazing ARDUINO Killer

    I noticed that the first one is not available anymore... Well, there is this one:https://www.aliexpress.com/item/STM32F103RCBT6-ARM...It even costs less now (3.03 $)... If you want more, I also saw 5pcs bundles for about 17.50$

    Totally right... You can search them on ebay or aliexpress, but here are some links of the ones I bought.I bought my first on Aliexpress (I looked for the cheapest one at the moment I bought it): https://www.aliexpress.com/item/STM32F103RCBT6-ARM...Then I thought I had broken it (it was heating a lot when powered and not connecting), so I needed to replace it quickly. I bought it again on Amazon.it with a 2-days delivery, paying almost 3 times as much (but getting it very quickly:https://www.amazon.it/gp/product/B016IV7MV4Then I noticed that it was just a wire short circuit on the solderings I made, so now I have two working maple mini ;) Anyway from China you can get them for 3-4$

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  • frarugi87 commented on HardiqV's instructable Amazing ARDUINO Killer3 weeks ago
    Amazing ARDUINO Killer

    I found exactly the same board as yours, but for a very similar price you can get the maple mini. It has the same STM32 micro you have, uses the same Arduino STM32 project, but has a great advantage: it comes with a pre-loaded bootloader. So no FTDI, no bootloader programming, nothing. Plug it in and it works. Just like an arduino board... Only with a much better hardware ;)

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  • Inexpensive Garage Lights From LED Strips

    I highly discourage you from using this approach. If you are using it in linear region, the MOS will just heat up and ... Smoke ;) PWM is used to reduce the power dissipated by the circuit, and is able to better control the luminous output. I'd use an 8-pin attiny for this job, rather than an arduino board, because the required peripherals are already there. You can still program them with the Arduino IDE, and as programmer you can use any 5V Arduino board (uno, mega, nano, ...)

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  • frarugi87 commented on smurray2's instructable RS232 Serial Spy2 months ago
    RS232 Serial Spy

    This works only when the connection is half duplex, right? Otherwise you will not be able to detect both channels..

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  • Pi 3, 2 the MaX for Under £5 - Overclocking - Automatic 2 Speed Cooling

    Why two MOS? Do you use one for a "low speed" variant? I think it is much better to use only one MOS and use PWM to change the speed...

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  • Arduino Nano USB Not Recognizing (Fix).

    I was a bit puzzled at your sentence "FTDI intentionally bricked several of my devices". What happened?

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  • frarugi87 commented on automatic-bartender's instructable Automatic Bartender2 months ago
    Automatic Bartender

    Why RPi and Arduino? I think only one would have been enough.... RPi has GPIOs, or ESP is a lot cheaper; if you want to go cheap use the ESP8266; if you want to make it more powerful (with a bigger database) go with RPi and use its GPIOs to use the pumps.

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  • frarugi87 commented on Henri.Lacoste's instructable Oak Mac mini Case5 months ago
    Oak Mac mini Case

    So you designed a magical box where you put a mac mini, close the lid, use the key to lock it and, after you turn it 360°, the mac disappears? ;-) nice case

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  • frarugi87 commented on Natural Nerd's instructable Vinyl Record Wall Clock - Iron Man6 months ago
    Vinyl Record Wall Clock - Iron Man

    One clock to rule them all... Very beautiful effect!

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  • frarugi87 commented on austiwawa's instructable DIY Color Changing Raw Wood LED Shelf6 months ago
    DIY Color Changing Raw Wood LED Shelf

    Usually the control algorithm is the same, so if you take two controllers you can control both with the same remote (but they won't be synchronized when you start an animation)

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  • Inexpensive garage lights from LED strips

    As the image clearly say, that one is the lighting efficiency (i.e. how much light you get versus the input power), while I was speaking about electric efficiency (i.e. how much power you convert in light versus the input power). Of course LEDs lighting efficiency is the highest among the "consumer" lamps, and I remarked it a lot of times, but they do waste a lot of energy, just like the old ones. Taking the values provided by Steven, a 100W incandescent bulb throws away 95W (and converts the other 5 in about 1500lm, so each "used" watt produces 300 lumens), while an LED throws away 90W (and gets about 10k lm, so about 1000 lumens per each "used" lumen). So the reason why LEDs are more lighting efficient is more related to the fact that they better convert ...

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    As the image clearly say, that one is the lighting efficiency (i.e. how much light you get versus the input power), while I was speaking about electric efficiency (i.e. how much power you convert in light versus the input power). Of course LEDs lighting efficiency is the highest among the "consumer" lamps, and I remarked it a lot of times, but they do waste a lot of energy, just like the old ones. Taking the values provided by Steven, a 100W incandescent bulb throws away 95W (and converts the other 5 in about 1500lm, so each "used" watt produces 300 lumens), while an LED throws away 90W (and gets about 10k lm, so about 1000 lumens per each "used" lumen). So the reason why LEDs are more lighting efficient is more related to the fact that they better convert the "used" power into light (because they output a narrower spectrum, thus avoiding the waste in IR and UV ranges) rather than because they dissipate less heat (because they still dissipate 90% of the input power)

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  • Hundreds of LEDs on Arduino: a New Way From the Past

    I was just starting to design an LED controller for one of my projects and was stuck with the driver selection. Now I think I found it.. Thank you!

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  • frarugi87 commented on deba168's instructable DIY Portable Mini Refrigerator7 months ago
    DIY Portable Mini Refrigerator

    Just a question: Why two fans on the main heatsink? Wasn't one enough?

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  • frarugi87 commented on thediylife's instructable Simple Arduino Home Energy Meter8 months ago
    Simple Arduino Home Energy Meter

    Good to know :) Thank you fot your instructable

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  • frarugi87 commented on thediylife's instructable Simple Arduino Home Energy Meter8 months ago
    Simple Arduino Home Energy Meter

    I'm a bit unsure that the two 100k resistors are suitable for this application. Can you measure the voltage between them to check that it is stable at Vdd/2 even when the CT is working? I would've put at least an OP-AMP or smaller resistors...Anyway for this kind of applications it's much better to use the internal voltage reference...

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  • Programmable Battery Protection [Open Source]

    Uhm.. Maybe there are two versions of your code, but in the image posted in step 5 there is a while loop (while (systemstate == 1)). You exit this loop (and consequently power off the MOS and enter the lop power state) only when the voltage is greater than the threshold AND the button is not pressed. If you enter this loop and the voltage decreases, you will never come out of it..As for the button/switch, sorry, I misunderstood ;) yes, with a switch it will work

    If I understood your program correctly, there are a couple of failure points (or at least I haven't understood everything).1) if you press the button and the battery is discharged, your load will not turn on (ok), but the attiny will never enter the low power mode until the battery is charged again. This is a bad behavior (it should enter the sleep phase immediately)2) as soon as you leave the button the load will be shut down (maybe this is the wanted behavior, though, but I think it is more useful if the button can act as a turn-on - turn-off button)3 and most important) while the load is powered, if the battery gets discharged the attiny will stop monitoring the button, thus leaving the load powered on even if the button is released. This is a real problem...I think that the first an...

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    If I understood your program correctly, there are a couple of failure points (or at least I haven't understood everything).1) if you press the button and the battery is discharged, your load will not turn on (ok), but the attiny will never enter the low power mode until the battery is charged again. This is a bad behavior (it should enter the sleep phase immediately)2) as soon as you leave the button the load will be shut down (maybe this is the wanted behavior, though, but I think it is more useful if the button can act as a turn-on - turn-off button)3 and most important) while the load is powered, if the battery gets discharged the attiny will stop monitoring the button, thus leaving the load powered on even if the button is released. This is a real problem...I think that the first and third points can be solved modifying your code indigitalWrite(mosfet, HIGH);while (systemstate == 1) {if (analogRead(voltdiv) < threshold)systemstate = 0;if (digitalRead(sw) == HIGH)systemstate = 0;}digitalWrite(mosfet, LOW);Moreover you can avoid using the systemstate variable, modifying the loop inwhile (1) {if (analogRead(voltdiv) < threshold)break;if (digitalRead(sw) == HIGH)break;}Best regards

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  • frarugi87 commented on volpin's instructable Creating Costume Armor with Wonderflex9 months ago
    Creating Costume Armor with Wonderflex

    The photos really look like that is an action figure... Great costume and great photos!

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  • frarugi87 commented on makjosher's instructable Cardboard Kitchen Cupboard Organizer9 months ago
    Cardboard Kitchen Cupboard Organizer

    I have to admit, english is not my native language, and when I first saw the first picture I said "no, probably cardboard is not what I think" because... Well, it doesn't look like cardboard anymore. It seems much more solid and professional. Very good job! And thanks for sharing

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  • How to Solder a Proper Plumbing Connection

    Without too many words, "I know one thing: that I know nothing" [Socrates]

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  • frarugi87 commented on balsuryana's instructable DIY Smartphone Notification Lamp11 months ago
    DIY Smartphone Notification Lamp

    The problem is that you can't "go for 10--15mA", because you can't set a current without a) a current supply or b) a resistor to try to set the current. The 1.5V battery circuit you propose is perfectly legit, but falls in my "cheap chinese-like circuits" class: good if you don't care about performances (your LED will not light completely, maybe your battery will not last its maximum life). And of course in this kind of circuits you will always have to use a lower voltage for the LED (1.5V for 2V leds, 2.5V for 3V leds), otherwise you will not be able to guarantee that it will not blow.In the end, I'm not stating that you can't power an LED without protections. I just want to point out that this, in my opinion, is a bad practice and should be avoided unless you are t...

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    The problem is that you can't "go for 10--15mA", because you can't set a current without a) a current supply or b) a resistor to try to set the current. The 1.5V battery circuit you propose is perfectly legit, but falls in my "cheap chinese-like circuits" class: good if you don't care about performances (your LED will not light completely, maybe your battery will not last its maximum life). And of course in this kind of circuits you will always have to use a lower voltage for the LED (1.5V for 2V leds, 2.5V for 3V leds), otherwise you will not be able to guarantee that it will not blow.In the end, I'm not stating that you can't power an LED without protections. I just want to point out that this, in my opinion, is a bad practice and should be avoided unless you are trying to use as few components as possible, as long as you are aware that in this case you will get very poor performances (for instance low light, shorter life or higher consumption with respect to results)

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  • frarugi87 commented on balsuryana's instructable DIY Smartphone Notification Lamp11 months ago
    DIY Smartphone Notification Lamp

    Well, since an LED (and diodes in general) are highly non-linear components, a small change in the voltage is translated into a high change in current. For instance this image shows the first graph I found searching on google. Passing from 3V to 3.1V will change the LED current from 1A to approx 1.5A, and at 3.2V it will be over 2A. And keep in mind that this varies with the temperature.Now, if you add a 0.1Ohm resistor in series, you will use approx 0.85A with 3V and 1A at 3.1V, going to around 1.2A at 3.2V.As you can see, without resistor small changes in the voltage will result in high changes in the current. If you have a 3V +- 5% source, you can get half the nominal current or double....So, according to my experience, there is no such thing as appropriate voltage. You can either ch...

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    Well, since an LED (and diodes in general) are highly non-linear components, a small change in the voltage is translated into a high change in current. For instance this image shows the first graph I found searching on google. Passing from 3V to 3.1V will change the LED current from 1A to approx 1.5A, and at 3.2V it will be over 2A. And keep in mind that this varies with the temperature.Now, if you add a 0.1Ohm resistor in series, you will use approx 0.85A with 3V and 1A at 3.1V, going to around 1.2A at 3.2V.As you can see, without resistor small changes in the voltage will result in high changes in the current. If you have a 3V +- 5% source, you can get half the nominal current or double....So, according to my experience, there is no such thing as appropriate voltage. You can either choose to protect it, using at least a resistor to limit the current to avoid overstressing both the LED and the driver (or better by using a current source instead of a voltage one), or decide you don't care about shortening the LED and the driver life, like they do in cheap chinese-like products.Period.PS: maybe you are saying this because in some circuits you made you didn't use it with some voltage outputs. Please note, however, that if you didn't get twice the current the reason is that every driver has a so-called output impedance. This is the reason why you didn't blow up your circuit nor the LED, and I totally agree it works. But this is exactly my second case: you are using the internal resistance to mitigate the effect of non-linearity, making the driver dissipate the power internally. This will definitely shorten its life; I'd prefer using a dedicated resistor (of which I know the power rating) rather than dealing with an unknown value/unknown power rating parasitic resistance to keep the circuit working...

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  • frarugi87 commented on balsuryana's instructable DIY Smartphone Notification Lamp11 months ago
    DIY Smartphone Notification Lamp

    Sorry, I couldn't understand what you meant, since it appears to me the opposite as what you were saying before. What I wrote is that you can't use it as a fuse, or using it saying "well, this will fry before the output", because it is not guaranteed. Maybe the led fries, maybe the output. For sure I will always use a resistor in series, even a very low value one if the source voltage is too low, but I'd never put an LED directly to a constant voltage source

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  • frarugi87 commented on balsuryana's instructable DIY Smartphone Notification Lamp11 months ago
    DIY Smartphone Notification Lamp

    It's maybe the LED, maybe the output stage of the audio port.. Who knows? For sure I'll never put a LED on an output I don't know without protecting it (it = the output port) with a resistor or other current-limiting protections

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  • frarugi87 commented on happydupa's instructable Inexpensive garage lights from LED strips11 months ago
    Inexpensive garage lights from LED strips

    Points 1 and 2, ok. Point 3. Well, for me wasting 95% or 85% of the input power in heat means wasting almost all the power. Mathematically speaking 85 < 95, but... Well, I would not change all of my house lamps to leds just because this is slightly better. Moreover there is more difference among different LEDs than between LEDs and other sources (the cheap LEDs on strips are unlikely to have an efficiency greater than 10%).Now, in my opinion saying that LEDs emit less heat because they waste a lower percentage of input power is misleading, because of course they do waste less energy, but the main reason is that LEDs produce much more light with respect to the power they use (not the input power, but the power they use).I'm just making a super-silly example: I switched from a low-end ...

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    Points 1 and 2, ok. Point 3. Well, for me wasting 95% or 85% of the input power in heat means wasting almost all the power. Mathematically speaking 85 < 95, but... Well, I would not change all of my house lamps to leds just because this is slightly better. Moreover there is more difference among different LEDs than between LEDs and other sources (the cheap LEDs on strips are unlikely to have an efficiency greater than 10%).Now, in my opinion saying that LEDs emit less heat because they waste a lower percentage of input power is misleading, because of course they do waste less energy, but the main reason is that LEDs produce much more light with respect to the power they use (not the input power, but the power they use).I'm just making a super-silly example: I switched from a low-end PC with Windows 7 to a high-end PC with Windows 10. My applications now run much faster than before. Now, looking at the benchmarks Win10 is slightly faster than Win7 (approx 5% faster), but don't you agree that saying "My applications run much faster because I changed OS" is misleading? Ok, it is mathematically faster, but maybe the reason is that the CPU is a high-end quad core CPU with hyperthreading instead of a slow old dual core one.That said, I totally agree with your point 0: this is getting really silly. So... I'll stop commenting here, also because the instructable was about a different subject. I'll continue saying that the way LEDs are so efficient is because they physically emit more light with the same power, you will continue saying that this is just because they waste less energy in heat, and we will both be happy..

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  • frarugi87 commented on happydupa's instructable Inexpensive garage lights from LED strips11 months ago
    Inexpensive garage lights from LED strips

    No, you aren't. And as I already told you a lot of times, it's true that LEDs, for comparable light, emit much less heat. What I told you, is that this is just because the LEDs require much less power. Taking your example, a 60W incandescent bulb generates (about) 57W of heat, while a 60W LED generates about 51W. It's very much similar. The real advantage is that to produce the same light of a 60W inc. bulb you just need a 6W LED, generating 5.1W of heat.So the reason why usually you say that LEDs emit less heat is that, for a comparable light, the LED require much less power, not that they "dissipate a lower proportion of the electrical energy".I've tried to say this in every possible way I could, so if you could not understand that I'm saying "you are right, I'm just qu...

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    No, you aren't. And as I already told you a lot of times, it's true that LEDs, for comparable light, emit much less heat. What I told you, is that this is just because the LEDs require much less power. Taking your example, a 60W incandescent bulb generates (about) 57W of heat, while a 60W LED generates about 51W. It's very much similar. The real advantage is that to produce the same light of a 60W inc. bulb you just need a 6W LED, generating 5.1W of heat.So the reason why usually you say that LEDs emit less heat is that, for a comparable light, the LED require much less power, not that they "dissipate a lower proportion of the electrical energy".I've tried to say this in every possible way I could, so if you could not understand that I'm saying "you are right, I'm just questioning that sentence because it was misleading", well, I'm just a master's degree electronic engineer with a PhD in electronics, not a linguistic, so I can't find any other way of saying this..

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  • frarugi87 commented on happydupa's instructable Inexpensive garage lights from LED strips11 months ago
    Inexpensive garage lights from LED strips

    Well, I suppose this depends on what you call "efficiency". As for the electric efficiency, I admin I don't know the electric efficiency of fluorescence light, but you have to admit that a loss of 85% of the power in heat (which is valid for power leds, but I doubt that the cheap LEDs on the chinese strips have this value) is very similar to the 95% of incandescent light. Then, as I told earlier, LEDs have a much higher luminous efficacy, so 1W of electric power into the LEDs generate much (much) more light than 1W of electric power into a CFL or incandescent light.Again, I'm not saying that changing your lights to LED technology will not reduce your heat. I'm just pointing out that the reason is not that they "dissipate a lower proportion of the electrical energy", ...

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    Well, I suppose this depends on what you call "efficiency". As for the electric efficiency, I admin I don't know the electric efficiency of fluorescence light, but you have to admit that a loss of 85% of the power in heat (which is valid for power leds, but I doubt that the cheap LEDs on the chinese strips have this value) is very similar to the 95% of incandescent light. Then, as I told earlier, LEDs have a much higher luminous efficacy, so 1W of electric power into the LEDs generate much (much) more light than 1W of electric power into a CFL or incandescent light.Again, I'm not saying that changing your lights to LED technology will not reduce your heat. I'm just pointing out that the reason is not that they "dissipate a lower proportion of the electrical energy", but because they better exploit the remaining part, and consequently you can reduce the input power.

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  • Inexpensive garage lights from LED strips

    In fact... LEDs have an electric efficiency of about 10%! This means that almost 90% of the electric power you give them is dissipated as heat. This varies a lot with the LED type and color (higher power leds are more efficient), but.. "dissipate a lower proportion of the electrical energy" is wrong ;) Then, since with that 10% they can emit a lot more light than other light sources, they light a lot with low power ;)

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