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  • Arduino Bike Speedometer with 128 x 64 Graphics LCD

    Really like this project. I particularly like the inclusion of a standard schematic as well as the Fritzing. I know by using the latter people can just copy exactly where you place the components and all will work but if you want to understand how things are connected then older people like me sometimes like a schematic.

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  • kcraske commented on farmerkeith's instructable DIY Logging Thermometer3 weeks ago
    DIY Logging Thermometer

    I think this is an excellent project. It is particularly good as it demonstrates how what looks like a complex end product can be broken down to smaller understandable parts to be put together to give an end result.

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  • How to Surface Mount Solder Using Solder Paste

    Tutorials such as this are really good considering the increasing number of smd components. Especially as some components are now only available as smd.

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  • kcraske commented on Jfieldcap's instructable LEDs for the Clueless Beginnner 1 month ago
    LEDs for the Clueless Beginnner

    Your calculation of the resistor needs a bit of refining as it assumes the use of a voltage around 5v. Your idea of generalisation is fine but I think you have got a bit confused when it comes to where you give the 1.8v. This is the volt drop that a red LED has, other colours vary. Limiting the current to about 15mA is a good generalisation. Now the calculation for the resistor. Let's say you have a 5v supply, The LED drops 1.8v so we need the resistor to drop 5-1.8 that requires 3.2v Using your ohms last v/i= r gives 3.2/0.015 = 213.333 so a 220 ohm resistor would be fine.Now look if you use a 2.4v supply, 2 batteries. The calculation now becomes 2.4 - 1.8 = 0.6. The resistor 0.6/0.015 = 40 ohms, much smaller. Looking again using a larger power supply say 24v. The calculation now becom...see more »Your calculation of the resistor needs a bit of refining as it assumes the use of a voltage around 5v. Your idea of generalisation is fine but I think you have got a bit confused when it comes to where you give the 1.8v. This is the volt drop that a red LED has, other colours vary. Limiting the current to about 15mA is a good generalisation. Now the calculation for the resistor. Let's say you have a 5v supply, The LED drops 1.8v so we need the resistor to drop 5-1.8 that requires 3.2v Using your ohms last v/i= r gives 3.2/0.015 = 213.333 so a 220 ohm resistor would be fine.Now look if you use a 2.4v supply, 2 batteries. The calculation now becomes 2.4 - 1.8 = 0.6. The resistor 0.6/0.015 = 40 ohms, much smaller. Looking again using a larger power supply say 24v. The calculation now becomes 24 - 1.8 = 22.2. The resistor 22.2/0.015 = 1480. Very much larger.Looking at the calculations you can see that calculating the voltage the resistor has to drop is more important when the power supply is just a bit bigger that the volt drop off the diode. If you use say a blue LED, this has a volt drop off about 3.3v so do the same calculations but use 3.3 instead of 1.8. An interesting point. If you use 2 batteries then you can light a red LED. But if you have a blue LED, the volts are only about 2.4v but the LED drops 3.3v so it would not light. Also, if you use a higher voltage you must be careful that the resistor can handle the power when it drops the voltage. In the last case, the power is v x I = 22.2 x 0.015 = 0.33 so you have to use at least a resistor variable of handling a third of a watt. As the power supply volts go up, so the value of the resistor goes up and also the amount of power the resistor has to get rid of goes up.Handy things LEDs, but you still have to do the maths.

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  • kcraske followed corneliusgray 1 month ago
      • How to Install a GPS Monitor
  • Designing a Dual 40A PWM Speed Controller for Brushed Motors

    An excellent description on how a circuit is developed by looking are the requirements sequencialy and adding the appropriate components as the project progresses.As I am in the middle of wanting to control motors using and Arduino I will find this useful.

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  • Fully Automated Arduino Roller Coaster Control System

    Absolutely fascinating.

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  • kcraske commented on DIY ZE's instructable Drone powered boat5 months ago
    Drone powered boat

    Love it. Thinking out of the box to use something in a way it was not intended.

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  • kcraske commented on Laurens-Wuyts's instructable Minimalistic Led Clock5 months ago
    Minimalistic Led Clock

    I just love anything to do with time and clocks. Thanks.

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  • kcraske commented on DrewPaulDesigns's instructable TRIPLE YOUR SOLAR ARRAY'S OUTPUT!5 months ago
    TRIPLE YOUR SOLAR ARRAY'S OUTPUT!

    An interesting idea which I would like to experiment with. However, right from the start there is a comment that light is not a possible particle but a wave and from there on everything is based on this statement.When dealing with light there is nothing wrong in dealing with the wave like properties of light but it is also shown the light also displays properties associated with particles. I would say that if you are to present an instructable in a scientific manner then you have to be accurate.Having said that, I still want to try this out.

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