KrakenKodersLights/VOLTAGE_DIVIDER_ALTERNATIVES.md

Voltage Divider Alternatives - Using What You Have

Solution 1: Using Only 2.2kΩ Resistors (RECOMMENDED)

Option A: Two 2.2kΩ in Series for Bottom Resistor

This creates a 2.2kΩ top and 4.4kΩ bottom divider.

PWM (5V) ────[2.2kΩ]────┬──── To D1 Mini D2 (3.33V)
                         │
                    [2.2kΩ]
                         │
                    [2.2kΩ]
                         │
                       GND

Output Voltage: 5V × (4.4kΩ ÷ 6.6kΩ) = 3.33V ✓ SAFE!

How to Build:

1. Solder white wire to first 2.2kΩ resistor
2. Connect other end to junction point
3. Solder TWO 2.2kΩ resistors in series from junction to ground
4. Take output from junction to D1 Mini D2

Option B: Equal Divider (Simplest)

Uses just two 2.2kΩ resistors for a 50/50 divider.

PWM (5V) ────[2.2kΩ]────┬──── To D1 Mini D2 (2.5V)
                         │
                    [2.2kΩ]
                         │
                       GND

Output Voltage: 5V × (2.2kΩ ÷ 4.4kΩ) = 2.5V ✓ SAFE!

Pros:

• Simplest to build
• Only 2 resistors needed
• Still safe for D1 Mini

Cons:

• Lower voltage might miss some PWM pulses in noisy environments
• But should work fine in most cases

Solution 2: Common Resistor Combinations

If You Have These Resistors:

Top Resistor	Bottom Resistor	Output	Safe?	Notes
2.2kΩ	4.7kΩ	3.4V	✓ Yes	Very common resistor
2.2kΩ	2.7kΩ	2.75V	✓ Yes	Close to ideal
2.2kΩ	3.9kΩ	3.2V	✓ Yes	Good alternative
2.2kΩ	2.2kΩ	2.5V	✓ Yes	Equal divider
1kΩ	2.2kΩ	3.4V	✓ Yes	If you have 1k
1kΩ	1.5kΩ	3.0V	✓ Yes	Perfect output

Solution 3: No Resistors? Emergency Options

Use LEDs as Voltage Droppers (NOT RECOMMENDED)

PWM (5V) ──── Red LED ──── To D1 Mini D2 (~3.3V)

• Red LED drops ~1.7V
• Output: 5V - 1.7V = 3.3V
• WARNING: Not reliable, use only for testing!

Use Diodes (Better than LEDs)

PWM (5V) ──── 1N4148 ──── 1N4148 ──── To D1 Mini D2 (~3.6V)

• Each silicon diode drops ~0.7V
• Two diodes: 5V - 1.4V = 3.6V
• Borderline safe - D1 Mini can usually handle 3.6V

Solution 4: Find Resistors in Old Electronics

Where to Look:

1. Old computer power supplies - Full of resistors
2. Broken LED bulbs - Often have 1kΩ-10kΩ resistors
3. Old TVs/Monitors - Tons of resistors
4. Broken phone chargers - Usually have some resistors
5. Old Arduino/electronics kits - Check breadboard projects

How to Identify Values:

Use online resistor color code calculator or multimeter

Solution 5: Make Your Own 3kΩ-ish Resistor

Parallel/Series Combinations:

To get ~3kΩ from 2.2kΩ resistors:

Option 1: 2.2kΩ + 1kΩ in series = 3.2kΩ Option 2: 2.2kΩ + 680Ω in series = 2.88kΩ Option 3: 2.2kΩ + 820Ω in series = 3.02kΩ

Quick Test Your Divider

With Multimeter:

1. Connect to 5V source (USB charger works)
2. Measure voltage at junction
3. Should read between 2.5V - 3.3V

Test Code for D1 Mini:

void setup() {
  Serial.begin(115200);
  pinMode(D2, INPUT);
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  // Read digital state
  int state = digitalRead(D2);
  digitalWrite(LED_BUILTIN, !state);
  
  // Try to read PWM
  unsigned long pulse = pulseIn(D2, HIGH, 50000);
  if (pulse > 0) {
    Serial.print("SUCCESS! PWM: ");
    Serial.println(pulse);
  } else {
    Serial.println("Waiting for PWM...");
  }
  delay(100);
}

Recommended Build with 2.2kΩ Only

Materials:

• 3× 2.2kΩ resistors
• Servo cable
• Small piece of wire

Steps:

1. Cut and strip servo cable (keep female end)
2. Build the divider:
   • White wire → 2.2kΩ → Junction
   • Junction → 2.2kΩ → 2.2kΩ → Black wire
   • Junction → Wire to D1 Mini D2
3. Connect power:
   • Red wire → D1 Mini 5V
   • Black wire → D1 Mini GND
4. Test it!

Visual Build:

  [Servo Cable]
       |
   R━━━B━━━W━━━━━[2.2k]━━━━●━━━━> To D1 Mini D2
   |   |                    |
   |   |              [2.2k]━━[2.2k]
   |   |                    |
   |   └────────────────────┘
   |
   └──> To D1 Mini 5V

Why These Work

The D1 Mini GPIO pins are rated for 3.3V but can tolerate up to 3.6V briefly. Any voltage between 2.5V and 3.3V will work reliably:

• 2.5V - Minimum reliable HIGH signal
• 3.0V - Ideal target
• 3.3V - Perfect match
• 3.6V - Maximum safe limit
• 5.0V - WILL DAMAGE THE D1 MINI!

Final Tips

1. When in doubt, measure! Use a multimeter if you have one
2. 2.5V is better than 5V - Lower voltage is safe, too high will kill the D1 Mini
3. Test with LED first - The onboard LED should blink when receiving PWM
4. Use what you have - Many combinations work, just stay under 3.6V

Shopping List (if you need to buy)

Minimum parts from Amazon/eBay:

• Resistor kit (~$5-10) - Includes hundreds of values
• 2.7kΩ resistor (5 pack ~$1) - Makes perfect 3V with 2.2kΩ
• 3kΩ resistor (5 pack ~$1) - Close enough to 3.3kΩ
• 4.7kΩ resistor (5 pack ~$1) - Common value, works great

Any of these will work perfectly with your 2.2kΩ resistor!