Category Archives: Computer

Computer, Tech

Analog Meters to display CPU and memory load

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While this is a old project from 2019, I decided to make a more responsive one, after my friend Tyrone mentioned a project somewhere on the internet (forgot where).
Time to dust off this project!

2019 version

Above version worked but was slow.
I used a python script to send values to de controller.

Memory setup was the same.

Below my new schematic, using an opamp to drive the analog meter.

Untested design .. Yeah I got bored on new year’s eve

Utilizing a MCP41000 digital potmeter and a LM358 signal amplifier I hope to get a more responsive setup.

Input to display MQTT and maybe Serial.

Old version
Computer

Added group control to my Mobile Pong game.

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Two player mobile pong using secure mqtt I made a few months ago.

Mqtt Pong

Today I tested my group playing mode while at family to celebrate xmas.

I was filming during testing to get responses. I can’t post this because of everyone being in the shot.

What worked:

  • Response of multiple mobile phones was good
  • Measuring average movement worked great
    (3 People moving up and one down? – going up)
  • 8 Players tested

To do:

  • Iphones have a problem sending tilt, I’ve got a problem with Iphones in general 🙂
  • Screen timeout, I have to add javascript to keep the mobile device screen on. No problem
  • Number of players on the left and number of players on the right visible in the screen. Do-able
  • Timeout for disapearing phones! ..
  • QR join code on the play screen
  • Starting ball futher away from paddle, to give player more time to react

Nice to have:

  • Muliple games at the same time. Now hard coded.
  • ?

Computer

Too many services/ports/ip numbers in your network to remember?

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Use a web server with a simple php script.

<?php
$host = $_SERVER['HTTP_HOST'];

$redirects = [
    'torrent.local'     => 'http://192.168.1.1:9091/',
    'nzb.local'     => 'http://192.168.1.1:8080/',
    'squeezebox.local'  => 'https://192.168.1.2:9000/',
    'squeeze.local'  => 'https://192.168.1.2:9000/',
];

if (isset($redirects[$host])) {
    header("Location: " . $redirects[$host], true, 302);
    exit;
}

http_response_code(404);
echo "Unknown host";

Add your webservers IP number to your local DNS server or hosts file

192.168.1.4 torrent.local
192.168.1.4 nzb.local
192.168.1.4 squeeze.local
192.168.1.4 squeezebox.local

Now you can use http://nzb.local in your browser and you will be redirected to http://serverip:port
No need to remember IP numbers or ports

Art, Computer, Tech

Made a JavaScript plugin for Hydra

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Control your effects using MQTT.

You can add anything to control your effects using RotaryEncoders, sensors and other data values.

I’m fixing the code to make use of free MQTT servers on the internet.
Then I’ll post the JavaScript in the Hydra forum or discord.


Calling the JavaScript in https://hydra.ojack.xyz/ website

https://gist.githubusercontent.com/fashice/2098d1301117b86caed94aca8f2101ff/raw/7d2a7300e7ddf42d4f1793f693dbb517e09bd2d8/gistfile1.txt
change mqtt server and add to hydra using
await loadScript("https://domain/script.js¨);
Computer, IOT / Domoticz

Giving people ability to control my Xmas lights

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At the WHY2025 hackers event, we used bigred’s antenna pole to make a huge sign using leds.

WHY2025

It gave me the idea to make a pole which displays digital “fireworks” using leds.
Fireworks are becoming illegal the next year in the Netherlands, I think.

So why not going digital?
12 Meter pole, 300 Leds.

There is a QR code and a website link mentioned on a page at the gate.
10 presets to select via a website.

Notification on my TV

While waiting for the first visitor I made a magnetic game.
Using a bunch of magnets, and 3D printed hexagon rings.
Two players try to place magnets in a small area without moving the others. If magnets slam together, you have more pieces to place.
(Below, last player has to take those 6 pieces)

CODE for website index.html

<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>WLED Mast</title>

<style>
body {
    background: #111;
    color: #fff;
    font-family: Arial;
    margin: 0;
    padding: 20px;
    text-align: center;
}
.grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 18px;
}
button {
    padding: 25px;
    font-size: 22px;
    border-radius: 20px;
    border: none;
    background: #333;
    color: #fff;
    font-weight: bold;
}
button:active {
    background: #555;
}
</style>
</head>

<body>

<h1>WLED Mast</h1>

<div class="grid">
    <button onclick="run('b1')">off</button>
    <button onclick="run('b2')">fireworks</button>
    <button onclick="run('b3')">sound<BR>reactive</button>
    <button onclick="run('b4')">bounch-balls</button>
    <button onclick="run('b5')">fire</button>
    <button onclick="run('b6')">juggle</button>
    <button onclick="run('b7')">swing</button>
    <button onclick="run('b8')">sparkle</button>
    <button onclick="run('b9')">popcorn</button>
    <button onclick="run('b10')">comet</button>
</div>

<script>
const API_KEY = "misuse-prevent";

function run(action) {
    fetch(`/action.php?action=${action}&key=${API_KEY}`)
        .then(r => r.json())
        .then(j => console.log(j))
        .catch(err => alert("Error"));
}
</script>

</body>
</html>

CODE for Wled API

<?php

$public_api_key = "misuse-prevent";
if (!isset($_GET['key']) || $_GET['key'] !== $public_api_key) {
    http_response_code(401);
    die("Unauthorized");
}

$action = $_GET['action'] ?? null;

// Map 10 buttons → WLED preset numbers
$allowed_actions = [
    "b1"  => 19,
    "b2"  => 22,
    "b3"  => 23,
    "b4"  => 20,
    "b5"  => 21,
    "b6"  => 3,
    "b7"  => 8,
    "b8"  => 2,
    "b9"  => 4,
    "b10" => 14
];

if (!$action || !isset($allowed_actions[$action])) {
    http_response_code(400);
    die("Invalid action");
}

$preset = $allowed_actions[$action];

// ---- WLED IP address ----
$wled_ip = "http://WLEDDEVICEIP";   // <-- CHANGE THIS

// API endpoint
$url = $wled_ip . "/win&PL=" . $preset;

// Call WLED directly
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 2);
curl_setopt($ch, CURLOPT_TIMEOUT, 2);

$response = curl_exec($ch);
$error = curl_error($ch);
curl_close($ch);

header("Content-Type: application/json");

if ($error) {
    echo json_encode(["ok" => false, "error" => $error]);
} else {
    echo json_encode(["ok" => true, "preset" => $preset]);
}
Computer

An idea I had to detect and count pages

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One of my old ideas, never made or tested.
I saw a post on Reddit with this question, I decided to post a little drawing using my idea.

Center of below picture shows pages (the lines), with coppertape going front to back and connect to following page

Inductive copper tape

Taking resistors of the same value, you’ll get a logarithmic voltage divider.
If you want the values evenly spaced, to make sure you are not misreading the value you have to make the resistors more like:
10k,6k,3k3,2k5,2k,1k68,1k5

3dprinting, Computer, Tech

Working on a (C64) handheld probe oscilloscope

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These will be available in my shop.

Probably a webpage with measured examples are usefull.

There is a cover for the pogo pin which holds the ground clamp

Handheld device to measure voltages and make screenshots using an application.

Control over serial

  • Select USB device to connect
  • Start a capture to screen
  • Clear (redraw probe screen)
  • Rotate screen for left/right-handed people and easy reading
  • Sample time speed in microseconds
  • 5V reading but 15 volt tolerant, due to the SID pins
  • ??? love to hear ideas

I’m currently working on streaming output.

Below, an example of screenshotting.

Below, measuring outputs from a NE555 (dutch comments)

Computer, IOT / Domoticz

Working on the garden lights POC

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Working on my garden lights

DIY Garden Lights.

Working 12V relay bottom left, and upper right the Raspberry $ compute module board with NodeRed.

I made a little board to program the ATTiny85.

The RS485 chip I wanted to use (SN65HVD3082) came as SMD, luckily I have some SMD to THT/DIL boards. (breakoff)

Above on the breadboard : The SN65HVD3082EP on a little pcb, the ATTiny85 .
4×4 WS2812 led matrix will be my dimmable RGB garden light.

Computer, IOT / Domoticz

Easy cheap touch light

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Remember those expensive touch lights you can buy?

This is a less than 5 euro version.

Warning : Some tricks I used

  • Using D5 as GND (I didn’t want to splice GND Wire.)
  • Using PWM for dimming
  • Using 5V led, use resistor if using a generic LED (220ohm)

TTP223 sensors are only a few cents!
And react even without touching (< 5mm)
So, you can build this in a case or behind fabric!

NOTE: If you are using an ESP32 you can configure a pin as touch!!!
So no TTP223 needed.
But ESP32 are more expensive as Wemos mini.

Code:

#define TOUCH_PIN D2 // My video has D7
#define LED_PIN   D6
#define FAKE_GND D5

// Brightness steps (0 = off, 255 = full bright)
int brightnessLevels[] = {0, 25, 125, 255};
int currentLevel = 0;
bool lastTouchState = LOW;

void setup() {
  
  pinMode(TOUCH_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  pinMode(FAKE_GND, OUTPUT);

  digitalWrite(FAKE_GND, LOW);  
  analogWrite(LED_PIN, brightnessLevels[currentLevel]);  // start OFF
}

void loop() {
  bool touchState = digitalRead(TOUCH_PIN);

    if (touchState == HIGH && lastTouchState == LOW) {
      // Advance brightness step
      currentLevel = (currentLevel + 1) % 4;  // 0-3 steps
      int pwmValue = brightnessLevels[currentLevel];
      analogWrite(LED_PIN, pwmValue);
    }

  lastTouchState = touchState;
}

Dim levels less obvious on recording, but you can change the levels in the code!