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  • Squeezing (seemingly) More Light From an LED

    pwm frequency?Actually: I have no idea :-)I simply use whatever the Timer1 library for Arduino creates. I think it is a few hundred Hertz.Definitely enough for me not to see any flickering, even at the lower intensities (the short pulses).So far I can tell tht running a 30W LED at 30% duty cycle (9W effective) looks brighter than a 10W LED at full power.My DSLR measures the 9W as lower - because that is the effect on the sensor.Next improvement to be done: implementing a higher PWM resolution. the 10bit (1024 steps nominal, 128 steps effective when using the value-squared scheme to approximate the eyes sensitivity curve) is a bit coarse. But still functional.The human eye can indeed be affected by 60Hz flicker (even more by the 50Hz flicker we have here in Europe).The reason is that the...see more »pwm frequency?Actually: I have no idea :-)I simply use whatever the Timer1 library for Arduino creates. I think it is a few hundred Hertz.Definitely enough for me not to see any flickering, even at the lower intensities (the short pulses).So far I can tell tht running a 30W LED at 30% duty cycle (9W effective) looks brighter than a 10W LED at full power.My DSLR measures the 9W as lower - because that is the effect on the sensor.Next improvement to be done: implementing a higher PWM resolution. the 10bit (1024 steps nominal, 128 steps effective when using the value-squared scheme to approximate the eyes sensitivity curve) is a bit coarse. But still functional.The human eye can indeed be affected by 60Hz flicker (even more by the 50Hz flicker we have here in Europe).The reason is that the time-resolution is different for the different parts of the retina.The central area has better spatial resolution (more detail) and better color resolution.The peripheral vision has a much better time resolution, so it can actually see flickering when the central-area sensons do not. I nthe brain, this is merged into a non-flickering picture with annoying side-effect - causing headache and other symptomps in some inviduals. This specially affects older people, because their exes are under more stess anyway (loss of sensor cells, loss of near-sight focus, slower focusing etc.).With incandescent bulbs, the effect was small: the glowing wire would not cool down very much in 1/120th of a second, so it smoothed out the light output, resulting in no flickering.Fluroescent bulbs/tubes flicker more - especially if they use a more fluroescent than phosphorecent converter. The phosphorescent substances are less bright, so the manufacturers were usually market-pressed to use the type with the bad side-effects.But all that goes away completely at a few hundred Hertz: that is too fast even for the peripheral ganglions (iirc. the sensors are similar, its the ganglions that to the first stage of computing on the picture, and this is slower on the central part to achieve the higher resolution; gosh, biology class was over 30 years ago...).Long story short: at 120Hz or 150Hz to be on the safe side, there is no flicker and no adverse effects.Your typical LED driver (constant current source; usually using a switching regulator of boost or buck topology) will run at a few hundred kilohertz, definitely zero flicker there.The cheaper types can not be dimmed, and the types that have a dimmer function usually reduce the LED current.This gives smooth dimming action, zero flicker but does not use the POV-effect I am using here.So I use pulse modulation of the output of a (very cheap) boost converter.

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  • hasenbaby commented on hasenbaby's instructable Arduino Device With Zero Standby Power6 months ago
    Arduino Device With Zero Standby Power

    That depends on your application.The quiescent current of the voltage regulator is anything but zero, the sleep mode still uses power...I do know that using low-power modes of the processor is the way, that "everybody" does it.And that is the reason my car uses almost 500mA when parked...When designing low-power applications, I usually use the Freescale ColdFire (the 68000 great-grandson) or the Energy Micro Gecko (ARM M0 with _very_ low power consumption, excellent optimization).Modding Arduino boards to use less power is imho actually more cumbersome than building an AVR circuit from scratch (Mega8+crystal+4 caps and appropriate power supply).But I have been asked the question "so, how about _really_ _zero_ standby? Can it be done?" by makers in my filterbubble.Suc...see more »That depends on your application.The quiescent current of the voltage regulator is anything but zero, the sleep mode still uses power...I do know that using low-power modes of the processor is the way, that "everybody" does it.And that is the reason my car uses almost 500mA when parked...When designing low-power applications, I usually use the Freescale ColdFire (the 68000 great-grandson) or the Energy Micro Gecko (ARM M0 with _very_ low power consumption, excellent optimization).Modding Arduino boards to use less power is imho actually more cumbersome than building an AVR circuit from scratch (Mega8+crystal+4 caps and appropriate power supply).But I have been asked the question "so, how about _really_ _zero_ standby? Can it be done?" by makers in my filterbubble.Such is the type of question that only stopps nagging and engineer when (s)he answered it conclusively.My answer: yes, can be done and here is, how.haseAnd btw: "how about with all solid state components?" - Does not look promising, still nagging me...

    Well, I used the labels that KiCAD had available, but I appreciate the input. Will do next time :-)Yes, Relay2 is the Reset for the (mechanical) Flip-Flop here.Powering that coil fro mthe controlled power - indeed an intriguiging idea.I'll give that a try in the prototype and see how that affects performance.In the current configutation the coil stays energized for a short moment after the 12V controlled power falls off. I intended this to make sure the relay stays energized long enogh for k1 to fall off.But indeed, this leave one high-impedance path for current from the battery to ground: via coil-k2 and the blocked Q2 and through the leakage resistance of the cap C1...In my tests this leakage current so far was not measureable (Radio Shack DMM, 16 years old, not calibrated).But using ...see more »Well, I used the labels that KiCAD had available, but I appreciate the input. Will do next time :-)Yes, Relay2 is the Reset for the (mechanical) Flip-Flop here.Powering that coil fro mthe controlled power - indeed an intriguiging idea.I'll give that a try in the prototype and see how that affects performance.In the current configutation the coil stays energized for a short moment after the 12V controlled power falls off. I intended this to make sure the relay stays energized long enogh for k1 to fall off.But indeed, this leave one high-impedance path for current from the battery to ground: via coil-k2 and the blocked Q2 and through the leakage resistance of the cap C1...In my tests this leakage current so far was not measureable (Radio Shack DMM, 16 years old, not calibrated).But using the controleld power would eliminate that path completely and also protect the circuit from spikes in the power supply (like the alternator starting up on engine start).Good Idea, I'll update my prototype.

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  • hasenbaby commented on hasenbaby's instructable Arduino Device With Zero Standby Power6 months ago
    Arduino Device With Zero Standby Power

    This ist part of a bigger project.A buddy of mine is making an old Sprinter into a camper/RV.When he planned to use an incanderescent lamp, I intervened and demanded to make an LED lamp instead.In the schematic there is a l12V output (to the right), which is controlled by the relays. This is the feed for the stepup converter drivind the LED.The irlz44 power FET is used to modulate the LED.The purpose of the power management is to save the battery when the LED is off (_zero_ standby).The push button turns it on, the rotary encode operates the dimmer function and the pushbuton also tells the firmware to kill power again.

    This ist part of a bigger project.A buddy of mine is making an old Sprinter into a camper/RV.When he planned to use an incanderescent lamp, I intervened and demanded to make an LED lamp instead.In the schematic there is a l12V output (to the right), which is controlled by the relays. This is the feed for the stepup converter drivind the LED.The irlz44 power FET is used to modulate the LED.The purpose of the power management is to save the battery when the LED is off (_zero_ standby).The push button turns it on, the rotary encode operates the dimmer function and the pushbuton also tells the firmware to kill power again.

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  • DIY CNC For 60$ (Large Work Area)

    Pretty well done!You will want to improve some parts soon - unless you are not using the machine :-)Make the gantry more stiff by adding a fin at a right angle to the board. I usually use metal profiles, but gluing some plywood tot he sides of the portal would already help, I guess.For the power supply, use the highest voltage your electronics can handle. The typical laptop power supplies have 19 to 21V and are pretty strong (60+ watts). Here in Germany you can pick up used laptop power supplies for very little money.I know that the grbl controller software is very popular, but I always recommend LinuxCNC.A used Core2Duo machine is usually available for reasonable money and if it is too modern (i.e. lacks a parallel port), a PCI parallel port card can be added for about 10$.I actually d...see more »Pretty well done!You will want to improve some parts soon - unless you are not using the machine :-)Make the gantry more stiff by adding a fin at a right angle to the board. I usually use metal profiles, but gluing some plywood tot he sides of the portal would already help, I guess.For the power supply, use the highest voltage your electronics can handle. The typical laptop power supplies have 19 to 21V and are pretty strong (60+ watts). Here in Germany you can pick up used laptop power supplies for very little money.I know that the grbl controller software is very popular, but I always recommend LinuxCNC.A used Core2Duo machine is usually available for reasonable money and if it is too modern (i.e. lacks a parallel port), a PCI parallel port card can be added for about 10$.I actually do almost all my CAM work (using Cambam) on the same Linux machine controlling the actual mill.anyway: congratulations on your ingenuity and skill.Keep making!hase

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