Building a Homemade Capacitor Charger from Scrap Parts

Introduction

As an electronics hobbyist, I often find myself in need of a capacitor charger to test circuits or power small devices. However, commercial capacitor chargers can be expensive. That's why I decided to build my own homemade capacitor charger using scrap parts I had laying around.

In this article, I will walk through the full process of building a homemade capacitor charger on a budget by repurposing scrap electronic components. I will cover:

• How a capacitor charger works
• Sourcing components from old devices
• Assembling the charger
• Adding safety features
• Testing and usage

I hope this DIY guide for constructing your own capacitor charger inspires you to make use of spare parts and reduce waste. With some basic soldering skills and remaining alert to safety, you can build a useful tool that rivals commercial products.

How a Capacitor Charger Works

Before we start collecting parts, let's review what a capacitor is and how a basic charger works.

A capacitor is a passive electronic component that stores energy in the form of an electrostatic field. It consists of two metal plates separated by an insulator or dielectric. When connected to a power source, electrons build up on one plate, inducing an opposite charge on the other. The capacitance, or the capacitor's ability to store charge, depends on the size of the plates and the properties of the dielectric.

A capacitor charger applies a DC voltage to charge the capacitor over time. The time required to fully charge a capacitor depends on its capacitance rating and the charging voltage.

Here is a simple capacitor charger circuit:

• Power supply - Provides DC voltage to charge the capacitor
• Current limiting resistor - Limits inrush current to prevent damage
• Capacitor - Stores energy from power supply
• Switch - Allows power supply to be connected/disconnected

With just these basic components, we can build our own functional capacitor charger. The specific parts we'll use are outlined next.

Sourcing Components from Scrap Devices

The great thing about this project is that many of the components can be salvaged from old electronics, saving money and reducing waste. Here are the parts I was able to source by scavenging scrap devices:

Power Supply

• Wall adapter power supply - Reused a 12V, 1A DC adapter from an old router

Current Limiting Resistor

• 47Ω 5W resistor - Salvaged from an old TV circuit board

Capacitor

• 4700μF 25V electrolytic capacitor - Found several in an old computer power supply

Switch

• SPST toggle switch - Pulled from a broken electronic toy

Housing

• Plastic project box - Repurposed from an old prototype project

The only parts I needed to buy new were hookup wire, binding posts to connect the capacitor, and a fuse for safety.

In total, I spent less than $5 building this capacitor charger using primarily repurposed components! Now let's look at how to assemble them into a working circuit.

Assembling the Homemade Capacitor Charger

With all the parts collected, it's time to assemble them into the complete charger circuit. I followed these steps:

1. Drill holes in the project box for mounting the power supply, switch, binding posts, and fuseholder.

2. Attach the components to the box using screws or adhesive.

3. Solder the positive terminal of the power supply to one side of the SPST switch.

4. Solder the other side of the switch to the current limiting resistor.

5. Connect the resistor to the positive binding post. This will connect to the positive capacitor terminal.

6. Solder the negative terminal of the power supply to the negative binding post. This will connect to the negative capacitor terminal.

7. Install a fast blow fuse between the power supply and switch to protect against short circuits.

Refer to the circuit diagram below for how all the components should be connected:

With the wiring complete, our homemade capacitor charger is built! But before we use it, we need to add some important safety features.

Adding Safety Features

Charging capacitors to high voltages can be dangerous, so I incorporated a few key safety enhancements:

• Discharge resistor - I soldered a 100kΩ resistor between the two binding posts. This slowly drains the capacitor when not in use to prevent shocks.

• Insulated binding posts - I used plastic-enclosed binding posts so no live terminals are exposed.

• Fuse - The fast blow fuse will quickly cut power if there are any shorts.

• Polarity markings - I marked the positive and negative terminals to prevent accidental reverse connection.

• Warning label - I added a visible label stating caution about the high voltages produced.

With these additions, I can safely charge capacitors without risk of shocks or damaging the charger from overloads.

Testing and Using the Homemade Capacitor Charger

With construction complete, it was time to test my homemade capacitor charger! I followed these steps for first-time use:

1. Make sure the capacitor is fully discharged before connecting. I used the built-in discharge resistor to bleed any residual charge.

2. Connect the positive and negative capacitor leads to their respective binding posts. Double check polarity is correct.

3. Plug in the power supply and turn on the switch. The capacitor will start charging up to the supply's 12V output.

4. Use a multimeter to measure the voltage across the capacitor. Over about 10 seconds, it should reach 12V as it charges fully.

5. Disconnect the capacitor and discharge it again through the resistor before handling to avoid shocks.

The charger performed exactly as expected during testing. I can now use it to charge capacitors for various experiments and projects!

Some examples of how I plan to use my homemade charger:

• Testing capacitor characteristics like leakage and ESR
• Providing power for hobby electronics like mini Tesla coils
• Charging flash capacitors to store energy from solar panels

By repurposing scrap parts rather than buying new, I was able to build an extremely affordable DIY tool that expands my electronics capabilities.

Summary

Constructing your own capacitor charger from old electronics components is an enjoyable and money-saving weekend project. This article covered:

• How capacitors and chargers work
• Identifying usable parts from e-waste
• Assembling a basic charging circuit
• Incorporating safety enhancements
• Testing for correct operation

With some basic soldering skills and safety awareness, you can build a capacitor charger tailored to your needs while reducing waste. I encourage you to explore salvaging scrap electronics and see what handy tools you can create!