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  • Simple and small full-bridge-rectifier

    Hi Tech... No, I'm not German. However, I'd love to know how the word "also" hints to you that I am. The system seems to have placed this single word apart from the rest of the paragraph without much of a reason for doing so. Is using that word by itself some sort of Germanic practice, or does it have a significant meaning when used in that language? Very curious about this though.

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  • Simple and small full-bridge-rectifier

    Just a quick comment to point out that there is a minor error in your schematic. The positive (+) output of the bridge rectifier goes to the negative (-) side of your capacitor. A simple enough error to make, and even easier to correct in your schematic. (Just move the '+' to the capacitor's bottom conductor, or flip the capacitor symbol vertically)This is a great 'ible that will be helpful to many beginners of electronics, but this small error could be problematic for them.- - - Edit - - - Also, the capacitor specified in the schematic and in the Parts List is "100uF", which seems to contradict the 1,000uF you've used on your board. Choosing a 1,000uF capacitor would be a much better choice in most cases, in addition to reducing the ripple, it would be more capable of supply...see more »Just a quick comment to point out that there is a minor error in your schematic. The positive (+) output of the bridge rectifier goes to the negative (-) side of your capacitor. A simple enough error to make, and even easier to correct in your schematic. (Just move the '+' to the capacitor's bottom conductor, or flip the capacitor symbol vertically)This is a great 'ible that will be helpful to many beginners of electronics, but this small error could be problematic for them.- - - Edit - - - Also, the capacitor specified in the schematic and in the Parts List is "100uF", which seems to contradict the 1,000uF you've used on your board. Choosing a 1,000uF capacitor would be a much better choice in most cases, in addition to reducing the ripple, it would be more capable of supplying the short, transient bursts of high-current whenever the load requires it.

    Just a quick comment to point out that there is a minor error in your schematic. The positive (+) output of the bridge rectifier goes to the negative (-) side of your capacitor. A simple enough error to make, and even easier to correct in your schematic. (Just move the '+' to the capacitor's bottom conductor, or flip the capacitor symbol vertically)This is a great 'ible that will be helpful to many beginners of electronics, but this small error could be problematic for them.- - - Edit - - - Also, the capacitor specified in the schematic and in the Parts List is "100uF", which seems to contradict the 1,000uF you've used on your board. Choosing a 1,000uF capacitor would be a much better choice in most cases, in addition to reducing the ripple, it would be more capable of supply...see more »Just a quick comment to point out that there is a minor error in your schematic. The positive (+) output of the bridge rectifier goes to the negative (-) side of your capacitor. A simple enough error to make, and even easier to correct in your schematic. (Just move the '+' to the capacitor's bottom conductor, or flip the capacitor symbol vertically)This is a great 'ible that will be helpful to many beginners of electronics, but this small error could be problematic for them.- - - Edit - - - Also, the capacitor specified in the schematic and in the Parts List is "100uF", which seems to contradict the 1,000uF you've used on your board. Choosing a 1,000uF capacitor would be a much better choice in most cases, in addition to reducing the ripple, it would be more capable of supplying the short, transient bursts of high-current whenever the load requires it.

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  • LaserDave commented on andrewwilson's instructable Emergency Stop Button 1 month ago
    Emergency Stop Button

    DC motors certainly do produce Back EMF during operation and generate electricity upon power removal, however, Universal motors contain no magnetics to act on the (decelerating) spinning windings and cannot generate electricity that could be used as a brake. While it's true that there is Back EMF produced while the motor is operating, it is due to the magnetic fields collapsing as the commutators break contact with each coil as it rotates. But that disappears as soon as power is removed.Unless there is a constant magnetic field to act on the coils as they decelerate, there will be no voltage generated to shunt and brake the motor. Any motor that contains permanent magnets will generate electricity (not Back EMF) that can be shunted (shorted) to produce a load on the motor to slow it down.

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  • LaserDave commented on tlp801's instructable Trash-Vac!!1 month ago
    Trash-Vac!!

    FetterChiller - At first glance that idea would appear feasible, but I am scratching my head about this particular fan because of its enormous THREE AMP power requirements. In my decades of experience, I have rarely encountered general-purpose fans that pulled anything over one amp.Most fans are efficient and draw low enough power as to permit continuous operation without taxing the system they are supposed to cool, so requiring power of this magnitude just for the fan boggles the mind and suggests that the device this fan was intended for would be expensive to run for any substantial time. I do realise that the author had this in his part bin, but that power supply is a beefy one that will continue to eat power while it's waiting to be used. Maybe you could switch the 110v instead.My s...see more »FetterChiller - At first glance that idea would appear feasible, but I am scratching my head about this particular fan because of its enormous THREE AMP power requirements. In my decades of experience, I have rarely encountered general-purpose fans that pulled anything over one amp.Most fans are efficient and draw low enough power as to permit continuous operation without taxing the system they are supposed to cool, so requiring power of this magnitude just for the fan boggles the mind and suggests that the device this fan was intended for would be expensive to run for any substantial time. I do realise that the author had this in his part bin, but that power supply is a beefy one that will continue to eat power while it's waiting to be used. Maybe you could switch the 110v instead.My suggestion for anyone considering the use of a 4.7" fan of this type, for this or any project, is to select one whose power requirements are much more reasonable such as those in desktop computers. Those fans typically draw half an amp or less at 12v, they are inexpensive and can be found in any electronics store or surplus vendor, with eBay being the best.

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  • LaserDave commented on AUGUSTO VJ's instructable EMERGENCY PHONE CHARGING HACK1 month ago
    EMERGENCY PHONE CHARGING HACK

    No, that's wrong, I think it is you who needs to study electronics, It seems you've mistaken Voltage for Current. With the exception of LEDs, electronic components do not 'take all they can get' and self-destruct. For any component, the manufacturer's spec sheet provides the minimum, typical, and maximum ratings for its Voltage and Current. Further, even IF every component required regulation, it would be automatically handled by the phone's power management system.It's the Current that varies in response to a load of a device's tasks. An example might be an LED clock, it will pull different Currents depending on the number of segments lit at any given time.Voltage, however, IS critical when powering circuitry. Voltage-sensitive components contain junctions and insulation that excess v...see more »No, that's wrong, I think it is you who needs to study electronics, It seems you've mistaken Voltage for Current. With the exception of LEDs, electronic components do not 'take all they can get' and self-destruct. For any component, the manufacturer's spec sheet provides the minimum, typical, and maximum ratings for its Voltage and Current. Further, even IF every component required regulation, it would be automatically handled by the phone's power management system.It's the Current that varies in response to a load of a device's tasks. An example might be an LED clock, it will pull different Currents depending on the number of segments lit at any given time.Voltage, however, IS critical when powering circuitry. Voltage-sensitive components contain junctions and insulation that excess voltages will destroy. Most components do have a voltage range within which they are happy and perform as expected, but that range can be very narrow. The voltage requirements of microprocessors is very strict, a minor deviation of even a fraction of a Volt can have extreme consequences. That aside, today's phones usually require 5 Volts with a small deviation tolerance. The reason is simple, the microprocessor monitors the incoming voltage and will reject anything out of range. This is somewhat paradoxical because the internal battery is usually rated at 3.7 Volts, and the processor is rated at a voltage that is lower still, typically between 1 and 3.3 Volts.There are many people offering comments containing sloppy or incorrect electronic information, so I will conclude my overly-thorough blather with a blurb about the car charger unit. This charging unit plugs into a vehicle's cigarette lighter to access the 10-15 Volt DC supply. Inside the chunky 'cube' resides a switching 'buck' converter circuit that provides 5 Volts after efficiently (> 85% typically) converting the input voltage that will accept (depending on model) between 6 and 30 Volts.

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  • LaserDave commented on deba168's instructable Make 4 Useful Things From 9V Dead Battery4 months ago
    Make 4 Useful Things From 9V Dead Battery

    I really don't like when alarmists reach for the "it could start a fire" card whenever something electrical is suspected of having even the slightest risk.First - the forward voltage of most white LEDs (in addition to blue, purple, pink etc.) is more than 3 volts, so that leaves us with 6 volts to deal with. The current through a 100-Ohm resistor at 6 volts is a mere 60mA, which is 0.36 Watts - MAX.Deduct from this value... the battery's internal resistance, the additional fraction of a volt for the LED's forward voltage (3.3v), and that these values were based on a full 9v battery. So, yes, a 0.25W resistor would be entirely appropriate. Fire? Have you ever seen a (sub 2W) resistor fail under extreme overload conditions? They turn black and burn out, sometimes with smoke, may...see more »I really don't like when alarmists reach for the "it could start a fire" card whenever something electrical is suspected of having even the slightest risk.First - the forward voltage of most white LEDs (in addition to blue, purple, pink etc.) is more than 3 volts, so that leaves us with 6 volts to deal with. The current through a 100-Ohm resistor at 6 volts is a mere 60mA, which is 0.36 Watts - MAX.Deduct from this value... the battery's internal resistance, the additional fraction of a volt for the LED's forward voltage (3.3v), and that these values were based on a full 9v battery. So, yes, a 0.25W resistor would be entirely appropriate. Fire? Have you ever seen a (sub 2W) resistor fail under extreme overload conditions? They turn black and burn out, sometimes with smoke, maybe even a 'crackle', but they don't burst into flames or produce enough thermal energy to ignite something nearby. Resistors are manufactured out of non-flammable materials designed to withstand heat.

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