j2i.net

The concept of transporting the heat produced by an appliance to the outdoors isn’t by any means new. Whether it is the hot air rising out of an oven or the exhaust from the dryer, it’s a concept implemented for generations. Less common in the home environment, however, is the heat from a computer. There are probably people mining cryptocurrency that have already tackled this problem. Though I’m not mining, I found myself faced with it when rendering video or playing a graphically intensive video game. I recently decided to do something about it. On the days I am working from home, it could sometimes become uncomfortably hot in my office though it is cool in the rest of the house. I thought it would be unreasonable to further cool the house just to make it more comfortable in one room; that feels like a waste of energy. Instead, I decided to evacuate the hot air from the computer before it spills out into the room.

I feel like there should be a ready-made solution available somewhere. But my searches turned up next to nothing. I did find an ant-miner adapter made for connecting a 4-inch hose to the antminer. This is a must have for what I’m doing! Four inches is the same diameter as the exhaust hoses used on many residential dryer. The computer in question is near a window. I started off looking for the adapters that are used for portable air conditions. These are usually made to better blend-in with the windows. I wasn’t able to find any that would work for my purposes. I did however find an adapter that was made for venting the air from a drive-through a window. This was perfect! It also used the same 4 inch fitting that the antminer adapter uses. The last major piece I needed was something to help move the air along the hose.

The exhaust fan on a computer is usually blowing air out into an open room. When that same airflow is directed through the dryer hose there may be some back-pressure to overcome. To compensate for this, was I initially was going to for an additional computer fan on the ant-miner adapter. When I tested this out with the 12-volt fan, the air flow was weak. I even tried slightly over-volting the fan to 14 volts to little effect. This was going to be inadequate. I was going to need a stronger solution. With a little more searching I discovered that I could also get 4-inch inline duct fans. This was perfect! There are a variety of duct fans available. For myself, I got a single speed fan. Other options to consider are do you want an inline fan to have a power switch on it, do you want it to be adjustable speed, and what flow rate you want it to have. The flow rate, usually expressed in Cubic Feet per Minute, tells what volume of air it can move over a minute. The higher this number, the more air it moves.

Before installing anything I fit the pieces together and turned it on. It was working great! when I turned it on I could see the shutters on the exhaust vent open a little. The fan, though audible, didn’t sound much different from the quiet sound of air flowing from an AC unit. For the installation, I had to remove the screen from my Window. The screen was designed to be easily removed and restored.

I wanted to be able to quickly attach and disconnect the exhaust vent to my computer. I’ve placed four magnets around the area of the back of the computer that the hot air comes from. I also placed four screws on the antminer adapter. When I line up the adapter with the magnets, it stays in place. There is also weather stripping material that came with the window adapter that I’ve placed on the edges of the ant miner adapter so that it better captures the hot air.

Drawbacks

Aesthetically, though the adapter was designed to better blend in with the window, it doesn’t completely blend in. Having to remove the screen from my window makes it visually different from my other windows. That’s a drawback. The exhaust duct is warm to the touch. This is expected, since there is warm air flowing through it. But this also means that some of the thermal energy is leaking through it into the room. An insulated duct could prevent this. Not that the current state is awful. Keep in mind previously 100% of the thermal energy was being dumped into the room before. As you might imagine, the window fitting does not block the transfer ot noise to/from the room as well as the double paned glass. If I were in a noisy environment, this could be problematic. I’d like a way to exchange the hot air with the outside without actually pushing air out the window. I’m sure the negative pressure that this solution puts on the room results outside air beign pulled into other areas of the house. An idea solution would perform the heat exchange with the outside without pushing out the air. That would be an air-condition.

Items Purchased or Suggested

Below you will find affiliate links to items that I used or that I would recomend that someone else consider if they decide to implement a similar solution for themselves.

Posts may contain products with affiliate links. When you make purchases using these links, we receive a small commission at no extra cost to you. Thank you for your support.

Mastodon: @j2inet@masto.ai
Instagram: @j2inet
Facebook: @j2inet
YouTube: @j2inet
Telegram: j2inet
Twitter: @j2inet

I was working with hardware that was sequential in coming off a production line. Looking at the hardwares’ serial number, I realized the numbers were mostly sequential, with the exception of the suffix on the serial number. I realized that I was looking at numbers suffixed with a checksum. I tried out a few checksum algorithms to figure out which one fit. This was only being done from curiosity.

One algorithm of special interest was Luhn’s algorithm. This is the algorithm that is used with IMEI, credit card numbers, and Canadian social security numbers. It’s a useful public domain algorithm. I’ve collected a few implementations of it here.

C++

bool pasesLuhnCheck(const string& cardNo)
{
    int nDigits = cardNo.length();
 
    int nSum = 0, isSecond = false;
    for (int i = nDigits - 1; i >= 0; i--) {
 
        int d = cardNo[i] - '0';
 
        if (isSecond == true)
            d = d * 2;
 
        // We add two digits to handle
        // cases that make two digits after
        // doubling
        nSum += d / 10;
        nSum += d % 10;
 
        isSecond = !isSecond;
    }
    return (nSum % 10 == 0);
}

C#

    public static bool CheckLuhnParity(string digits)
    {
        bool isValid = false;

        if (!string.IsNullOrEmpty(digits))
        {
            long sum = 0;
            int parity = digits.Length % 2;
            for (int i = 0; i < digits.Length; i++)
            {
                int digit = digits[^(i + 1)] - '0';
                sum += (i % 2 == parity) ? Luhn(digit) : digit;
            }
            isValid = (sum % 10) == 0;
        }
        return isValid;
    }

Kotlin

fun IsValidLuhnString(entry:String): Boolean {
    var sum = 0
    var isSecond = false
    for( i in entry.length-1..0) {
        val multiplier = if(isSecond) { 2} else {1}
        val digit = entry[i].digitToInt() * multiplier
        sum += digit / 10;
        sum += digit % 10
        isSecond = !isSecond
    }
    return (sum % 10) == 0
}

JavaScript

const luhnCheck =( num, radix) => {
    if(radix == null) { 
        radix = 10
    }
    const arr = `${num}`
      .split('')
      .reverse()
      .map(x => Number.parseInt(x, radix));
    const lastDigit = arr.shift();
    let sum = arr.reduce(
      (acc, val, i) =>
        i % 2 !== 0 ? acc + val : acc + ((val *= 2) > 9 ? val - 9 : val),
      0
    );
    sum += lastDigit;
    return sum % 10 === 0;
  };

You can find a JavaScript/HTML implementation of it at https://j2inet.github.io/apps/luhns. Though this example doesn’t engage in any network communication, while I encourage you to try it out, please don’t use your bank card. Better yet, if you want to examine the code locally, there is also a download link on that page that contains all of the source code.

Posts may contain products with affiliate links. When you make purchases using these links, we receive a small commission at no extra cost to you. Thank you for your support.

Mastodon: @j2inet@masto.ai
Instagram: @j2inet
Facebook: @j2inet
YouTube: @j2inet
Telegram: j2inet
Twitter: @j2inet

I came across something that I thought was cool, though not something I would ever use. It was a set of C++ defines for Japanese language coders that let’s them write in C++ using Japanese words in the place of various C++ control statements and key words. The repository for this project can be found at https://gist.github.com/HerringtonDarkholme/2dbb2a1ec748a786f54908320447b3dd. Here are a few lines from the code.

#define  エスティーディー std
#define アイオーストリーム <iostream>
#define  ユージング using
#define イフ if
#define インクルード #include
#define イント int

You can probably guess what is going on here, but I will explain. The Japanese characters here are Katakana. They are commonly used to phonetically spelling out words from other languages. The very first define here is kind of clumsy. It spells out how we would say std. As in ess-tee-dee. The rest of the defines spell out the English pronunciations of the words. I found out about this by way of the following tweet, which showed some C++ written using a substantial amount of Japanese.

While it looks cool, I have a preference of minimizing my use of defines in my C++ code. But I’m also not a native 日本語 speaker. I imagine this provides some advantages for someone that is.

Posts may contain products with affiliate links. When you make purchases using these links, we receive a small commission at no extra cost to you. Thank you for your support.

Mastodon: @j2inet@masto.ai
Instagram: @j2inet
Facebook: @j2inet
YouTube: @j2inet
Telegram: j2inet
Twitter: @j2inet