The Variable Voltage Converter is a device that takes in an input voltage up to 12V and outputs a converted voltage at the output terminals, either higher or lower than the input voltage. This output voltage can be adjusted via a potentiometer on the board. It also has a main power switch that toggles the input voltage to the converter circuit.
Below are photos showcasing the final schematic sections and printed circuit board design for the project.
Entire Schematic
PCB 2D View
PCB 3D View - Front
PCB 3D View - Back
Below is a table containing all of the parts as well as a link to the Digikey parts list.
| Part Name | Count | Cost Per Part |
|---|---|---|
| 2-Input Terminal Block | 2 | $1.33 |
| 100V 1A SMD Diode | 1 | $0.17 |
| LM555 Timer IC | 1 | $1.20 |
| 100kΩ Trimmer Potentiometer | 1 | $2.58 |
| 0.1µF 1206 Capacitor | 2 | $0.08 |
| IRLZ44NSTRLPBF MOSFET | 1 | $1.48 |
| 1µF 1206 Capacitor | 1 | $0.12 |
| 0.33µF 1206 Capacitor | 1 | $0.10 |
| 1kΩ 1206 Resistor | 1 | $0.10 |
| 4.7µH Inductor | 1 | $2.26 |
Using the Device such as Pinouts or Setup is detailed below.
Below is information and necessary tables of pinouts for the device.
| Pin Technical Name | Pin Name | Pin Info |
|---|---|---|
| J1 - 1 | Vin | Input Voltage |
| J1 - 2 | GND | Input GND |
| J2 - 1 | Vout | Output Voltage |
| J2 - 2 | GND | Output GND |
To setup, input an input voltage (up to 12V) and ground into terminal J1. Next, wire the output terminal block, J2, as Vout and another ground line. From there, flip the switch to enable the circuit, and adjust the potentiometer to adjust the output voltage as needed.
Challenges, What I Learned, and More.
The challenge of this project I'd say was finding parts capable of handling higher voltages and currents than my previous Voltage Boost Converter. I talk about this further in the "What I Learned" section below, but in particular finding a small yet high voltage high current capable on/off switch was a challenge, as well as finding an inductor small enough for the board yet capable of carrying high voltages and high currents for larger duty cycles.
In doing this project I learned to more closely analyze the specifications of the parts that I selected. In my original Voltage Boost Converter project that inspired this improved version, my inductor carried too much current and began melting at higher voltages, and due to higher current running through the inductor on higher duty cycles. To counteract this, I had to learn to analyze inductor datasheets to find an inductor capable of carrying a higher saturation current to prevent overheating.
This project is an improved iteration of my original Voltage Boost Converter project. That project was originally inspired by a Boost Converter circuit made by Benjamin Marshall, which I originally intended to recreate for my Coil Gun project to charge high- rated capacitors to a high voltage for a stronger electromagnetic field within the coil.
