Dynamo Rear Light & USB Charger

Summary:

This device is a simplified AC to DC converter using a capacitor and rectifier, regulated to 5V, to power a rear LED or charge a battery pack for headlights or your phone. The 12V dynamo generates power, which is converted from AC to DC by the bridge rectifier. The capacitor stabilizes the voltage, and the voltage regulator limits it to 5V. A toggle switch diverts the power to either the rear LED or the USB port for charging.

Background:

I created this simple dynamo power supply during COVID when my friends and I would go out for cycles. This design is very minimalist, and the electronics are arranged in a 3D structure, which was an interesting experience to solder. For the fun of it, I also decided to include a missile-launch switch cover for the power diversion switch.

Components:

1. 1.5A 400V Bridge Rectifier
2. 1000µF 35V Radial-Lead Electrolytic Capacitor
3. 3 Pin +5V 1A Fixed-Voltage Regulator
4. Toggle Switch
5. USB 2.0 Port
6. ±m5 Torsion Spring
7. Two m3 bolts and nuts
8. 3W White Power LED Star with Resistor

Setup:

• 12V Dynamo: Mounted on the rear wheel to generate power.
• Mounting Location: Pole beneath the seat.
• Usage: Powers rear LED light or charges a battery pack/phone via USB.

Special Feature:

• Switch Guard: Spring-closing, missile-style switch guard for protection.

With this setup, you can either power the rear LED or use the USB port to charge a battery pack for your front LEDs and phone.

Wiring Instructions:

1. Rectifier Connection:

   • Connect the AC outputs from the 12V dynamo to the AC inputs on the bridge rectifier.

2. Capacitor Connection:

   • Connect the positive DC output of the rectifier to the positive lead of the capacitor.
   • Connect the negative DC output of the rectifier to the negative lead of the capacitor.

3. Voltage Regulator Connection:

   • Connect the positive lead of the capacitor to the input pin of the voltage regulator.
   • Connect the negative lead of the capacitor to the ground pin of the voltage regulator.

4. Toggle Switch Connection:

   • Connect the output pin of the voltage regulator to the common terminal of the toggle switch.
   • Connect the ground pin of the voltage regulator to the common ground.

5. USB Port and LED Connection:

   • Connect one terminal of the toggle switch to the positive lead of the USB port and the other terminal to the positive lead of the LED (with resistor).
   • Connect the USB port ground and LED ground to the common ground.
6. Final Assembly:
   • Mount all components securely in the project enclosure.
   • Ensure all connections are insulated and secure.
   • Attach the missile-launch switch cover over the toggle switch for protection.

Ensure all connections are secure and check polarity before powering the system.

This setup will allow you to switch between powering the rear LED light and charging via USB.

Components & Photos:

1. 1.5A 400V Bridge Rectifier
   Converts AC to DC.

   

2. 1000µF 35V Radial-Lead Electrolytic Capacitor
   Stabilizes voltage.

   

3. 3 Pin +5V 1A Fixed-Voltage Regulator
   Provides consistent 5V output.

   

4. 3 State Toggle Switch
   Switches between powering the rear LED light and USB output.

   

5. USB 2.0 Port
   For charging power bank.

   

6. ±m5 Torsion Spring

   
7. 3W White Power LED Star
   • https://kitronik.co.uk/products/3548-3w-white-power-led-star?_pos=48&_sid=91bba9586&_ss=r