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  • starphire commented on akolk1's instructable Huge addressable RGB LED (ceiling) panel2 months ago
    Huge addressable RGB LED (ceiling) panel

    Regarding power requirements, there is a hidden power leech in the 12V WS2811 pixels and strips- each controller IC still needs 5V, which is supplied by a zener diode and a resistor. Most of the idling power draw (no LEDs lit) goes into feeding all of those little zener voltage regulators, which really adds up for hundreds of pixels! The 5V versions (WS281201/12) don't have this issue..So for a little more money one could instead wire 3x as many 5V strips in the same area and get the same light output with more resolution and noticeably lower average power consumption. i.e. higher efficiencyA rule of thumb for RGB light arrays is that actual power draw will typically be about 1/2-1/3 of theoretical maximum unless the effects are heavy on white and pastel fills. Excluding power leeches f...see more »Regarding power requirements, there is a hidden power leech in the 12V WS2811 pixels and strips- each controller IC still needs 5V, which is supplied by a zener diode and a resistor. Most of the idling power draw (no LEDs lit) goes into feeding all of those little zener voltage regulators, which really adds up for hundreds of pixels! The 5V versions (WS281201/12) don't have this issue..So for a little more money one could instead wire 3x as many 5V strips in the same area and get the same light output with more resolution and noticeably lower average power consumption. i.e. higher efficiencyA rule of thumb for RGB light arrays is that actual power draw will typically be about 1/2-1/3 of theoretical maximum unless the effects are heavy on white and pastel fills. Excluding power leeches for the controller ICs, that is.

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  • How to Make a Dehumidifier (Thermoelectric Cooling)

    OK, if you need only a small number of Watts of cooling power to effectively dehumidify a space and you can get your power free from the sun. So perhaps to control the humidity in a drawer, or small cabinet. Anything more than that, it still doesn't make sense.Many commenters here seem to think that could be enough to dehumidify a room, or even a whole basement. An average "room" dehumidifer uses about 500W, and the adjacent air and soil provides essentially unlimited fresh humidity into a space that's being actively dehumidified, so a duty cycle of 100% is not unusual. In the Northeastern US, it can easily cost hundreds of dollars worth of electricity to run a dehumidifer half of the year: http://www.cadmusgroup.com/wp-content/uploads/2012/11/Dehumidifier-Metering-Study-Matti...see more »OK, if you need only a small number of Watts of cooling power to effectively dehumidify a space and you can get your power free from the sun. So perhaps to control the humidity in a drawer, or small cabinet. Anything more than that, it still doesn't make sense.Many commenters here seem to think that could be enough to dehumidify a room, or even a whole basement. An average "room" dehumidifer uses about 500W, and the adjacent air and soil provides essentially unlimited fresh humidity into a space that's being actively dehumidified, so a duty cycle of 100% is not unusual. In the Northeastern US, it can easily cost hundreds of dollars worth of electricity to run a dehumidifer half of the year: http://www.cadmusgroup.com/wp-content/uploads/2012/11/Dehumidifier-Metering-Study-Mattison-050912.pdf A Peltier cooler is 1/3 as efficient, roughly speaking (yes, it really is TERRIBLE efficiency in comparison to mechanical refrigeration). So a comparable Peltier-based dehumidifer would need about 1500 Watts to do the same work.So if someone needs enough cooling power to justify even a very small commercial dehumidifier, and they would like to make the most efficient use of their spare solar panels it would be better by far to convert the DC output of the solar panels to AC using an inexpensive inverter, and use that to power their mechanical dehumidifer. A single Peltier device being used to draw moisture from the air is a nice demonstrator of the concept, but it is basically a toy for most of the applications where dehumidification is needed.

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  • How to Make a Dehumidifier (Thermoelectric Cooling)

    Despite a lot of hopeful comments here (maybe based on the false impression that Peltier devices offer high efficiency for cooling), any basement-scale dehumidification really would make more sense using a traditional compressor-based refrigeration system if it is to be affordable to operate, or for it to have sufficient capacity (as noted by JerryS42) without spending massive amounts of money on Peltier devices (and generating 3x the amount of waste heat in the process).How the cooling loops are arranged to collect condensation, or how waste heat is removed from the cooler, is more adaptable to personal choice and experimentation though.

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  • How to Make a Dehumidifier (Thermoelectric Cooling)

    @toddbatzler, reading through all of the comments it seems yours is the most honest and reasonable comment regarding the actual efficiency of this device. Many people seem to have no idea just how much energy is needed to dehumidify basements, etc. in humid climates. Peltier devices have been available for several decades, but never replaced traditional cooling systems for good reason! They are ONLY a better choice than mechanical refrigeration pumps when portability, small size, or quietness are absolutely required features and efficiency (and cost, in utility bills) can be sacrificed in exchange for these special cases. It is laughable to call any Peltier-based cooling or dehumidification device "efficient", unless perhaps comparing it to some even worse method - like repeat...see more »@toddbatzler, reading through all of the comments it seems yours is the most honest and reasonable comment regarding the actual efficiency of this device. Many people seem to have no idea just how much energy is needed to dehumidify basements, etc. in humid climates. Peltier devices have been available for several decades, but never replaced traditional cooling systems for good reason! They are ONLY a better choice than mechanical refrigeration pumps when portability, small size, or quietness are absolutely required features and efficiency (and cost, in utility bills) can be sacrificed in exchange for these special cases. It is laughable to call any Peltier-based cooling or dehumidification device "efficient", unless perhaps comparing it to some even worse method - like repeatedly baking out dessicant so that it can be used to "efficiently" remove humidity from a dank closet.

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  • starphire commented on taifur's instructable Convert $2 LED Lamp to $50 Smart Lamp2 months ago
    Convert $2 LED Lamp to $50 Smart Lamp

    It will be harder to find LED bulbs in the US that have this kind of direct-rectified power supply (it will also have half as many white LEDs inside, to match the lower voltage. Almost all LED bulbs sold here now use a better power supply in their base, which is also usually dimmable without flicker. So finding a bulb with this size and space inside may be difficult in some countries, or it may not be so compatible to control with your design. But it is a nice design for the bulb you have.It also looks like you can turn on both the white *and* the RGB LEDs at the same time using this app setup. However, I would caution against doing this for more than a minute or two, since the heat from the white LEDs and the 5V power converter will make the temperature inside the bulb hot enough to co...see more »It will be harder to find LED bulbs in the US that have this kind of direct-rectified power supply (it will also have half as many white LEDs inside, to match the lower voltage. Almost all LED bulbs sold here now use a better power supply in their base, which is also usually dimmable without flicker. So finding a bulb with this size and space inside may be difficult in some countries, or it may not be so compatible to control with your design. But it is a nice design for the bulb you have.It also looks like you can turn on both the white *and* the RGB LEDs at the same time using this app setup. However, I would caution against doing this for more than a minute or two, since the heat from the white LEDs and the 5V power converter will make the temperature inside the bulb hot enough to compromise the life of the RGB LEDs. This style of RGB LED is already pushed past its limits of heat tolerance at room temperature with all three LEDs inside at 100% power-the epoxy and long pins are poor heat conductors. It is not dangerous, but it is not good for reliable long life of one's handmade Smart Bulb. Best to keep using this bulb in open air, to help keep its temperature down and be kind to the electronics inside!

    If you begin with a white LED bulb which has only a bridge rectifier and capacitors to power it normally, then you MUST use a bulb made to operate at your country's AC line voltage-these type of cheap bulbs are not able to work on both 110V and 230V-a mismatch would either be very dim and flickery, or burn itself out immediately. They are actually getting hard to find in some countries (like the US), since they flicker so badly and even inexpensive LED bulbs from many sources now have tiny switching power supplies inside which convert to a much lower voltage to power the LEDs.

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  • A Guide for Buying LED's on E Bay ---- Part TWO

    In the sense that white LEDs are a rapidly evolving technology, there is much potential for confusion because what was cutting edge even a year ago is already becoming obsolescent, and design/manufacturing/sales simply can't keep all competitors at the same price/performance/quality - in that sense it is sort of a Wild West. That ALSO makes comparison reviews by organizations such as CR practically useless for specific models of LED bulbs, as they are being upgraded and replaced (and prices slashed) faster than their publishing cycles can possibly keep up to date with. The best they can do is to give general educational guidelines for consumers to do their own comparisons.And this is where labeling standards come in, as the FTC in the US has required that all LED bulbs adhere to a stand...see more »In the sense that white LEDs are a rapidly evolving technology, there is much potential for confusion because what was cutting edge even a year ago is already becoming obsolescent, and design/manufacturing/sales simply can't keep all competitors at the same price/performance/quality - in that sense it is sort of a Wild West. That ALSO makes comparison reviews by organizations such as CR practically useless for specific models of LED bulbs, as they are being upgraded and replaced (and prices slashed) faster than their publishing cycles can possibly keep up to date with. The best they can do is to give general educational guidelines for consumers to do their own comparisons.And this is where labeling standards come in, as the FTC in the US has required that all LED bulbs adhere to a standard labeling (since 2012) to allow consumers to do basic comparisons in store - just like a nutrition label.

    One danger with this approach is that it leaves your LEDs highly vulnerable to voltage spikes (which are more common than most realize, and usually absorbed by protective devices in modern power supplies). The peak *reverse* voltage on Light Emitting Diodes is usually low compared to bulk rectifiers designed for the purpose, so that can leave little margin for recovery from spikes induced by nearby lightning or inductive kickbacks from large motors, etc. For low cost holiday lights and such, they are not meant to last that long anyway.Whether 50/60 Hz or 100/120 Hz (putting a half wave rectifier inline), the flicker shows up in enough situations to make it undesirable to a lot of people as general lighting. A few companies have tried to commercialize the AC driverless approach with seri...see more »One danger with this approach is that it leaves your LEDs highly vulnerable to voltage spikes (which are more common than most realize, and usually absorbed by protective devices in modern power supplies). The peak *reverse* voltage on Light Emitting Diodes is usually low compared to bulk rectifiers designed for the purpose, so that can leave little margin for recovery from spikes induced by nearby lightning or inductive kickbacks from large motors, etc. For low cost holiday lights and such, they are not meant to last that long anyway.Whether 50/60 Hz or 100/120 Hz (putting a half wave rectifier inline), the flicker shows up in enough situations to make it undesirable to a lot of people as general lighting. A few companies have tried to commercialize the AC driverless approach with series LEDs in one package, with little success in the marketplace.

    I was just thinking that's one niche of LED product where "you get what you pay for" is NOT necessarily true. Tons of junk ads out there lately for really cheap, low quality "tactical lights" with extremely misleading or dishonest advertising pretending they are "military" grade, which is clearly targeted at people with no real experience of modern LED flashlights. They are actually charging MORE than a good brand name light from the store, for something imported in bulk from China for a tiny fraction of the cost of a decent one at the hardware store. It's predatory marketing that ensures you actually get LESS than what you'd pay for through local channels, yet some will still think it's an improvement on their ancient flashlight.

    With LED bulbs now selling for as little as a few dollars, even that's not really true anymore. But it's more complicated than that. There can be a variety of other reasons for choosing LED over CFL, including better performance in more directional types of bulbs (efficacy is a better measure than raw efficiency, i.e. useful light reaching the target vs Watts used, an area where ALL fluorescent type bulbs are at a disadvantage for directional lighting); to avoid the danger of broken glass and mercury contamination; better performance in more extreme temperatures (CFLs being slow to get to full brightness) and very short-cycle uses; higher risk of fire from aging CFLs (high voltage arcing). Theoretically much longer life as well, though that depends on the quality of design and manufactu...see more »With LED bulbs now selling for as little as a few dollars, even that's not really true anymore. But it's more complicated than that. There can be a variety of other reasons for choosing LED over CFL, including better performance in more directional types of bulbs (efficacy is a better measure than raw efficiency, i.e. useful light reaching the target vs Watts used, an area where ALL fluorescent type bulbs are at a disadvantage for directional lighting); to avoid the danger of broken glass and mercury contamination; better performance in more extreme temperatures (CFLs being slow to get to full brightness) and very short-cycle uses; higher risk of fire from aging CFLs (high voltage arcing). Theoretically much longer life as well, though that depends on the quality of design and manufacturing to some degree.

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  • starphire commented on Vulcaman's instructable DIY-SLS-3D-Printer5 months ago
    DIY-SLS-3D-Printer

    I completely agree about being extra careful with eye safety/goggles/shields for something like this.However, it would be overly simplistic to say that you can judge the blocking ability of laser safety goggles purely by their apparent color. If such goggles are relying solely on the colored dyes added to polycarbonate during manufacture, their ability to attenuate a laser in wavelengths they don't normally "pass" very well, they are not going to reduce the beam by very many magnitudes - a dark tinted pair of grey sunglasses could even in some cases be measurably more effective. Really high quality laser safety glasses are not simple colored gel filters in principle.

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