Open Heart Effects Voltage Doubler PCB

A voltage doubler is a handy thing to have if you're making or modifying pedals. This one uses charge-pump technology to turn a positive input voltage into its equivalent negative output voltage. You can use it as a balanced dual supply or as a single supply of double the input voltage. For example, if you have a 9V input, you can use the output as +9V, ground, and -9V or you can use the output as +18V and ground.

I'll include a schematic with the board and there's a video of the assembly process at above.

This listing includes only the printed circuit board. Here's what you'll need to complete the project:

• 2x 10Ω 1/4W 5% resistor (Yageo CFR-25JB-52-10R for example)
• 5x 100µF 16V 20% capacitors (Nichicon UVR1C101MDD or equivalent)
• 1x TC7660H charge pump IC (Microchip Technology TC7660HEPA or equivalent)

This design is meant for input voltages between 3.0 and 10.0 Volts and output loads up to 10mA. Be aware that the charge pump does use an oscillator, which will produce some ripple on both the input and output and may be important for sensitive designs. If you use the TC7660H as recommended, the frequency of oscillation should be around 120kHz – well outside of the normal audio frequency range. Even so, I've included filtering on both the input and output in the design. Efficiency is less than 100% and there is some additional voltage drop through the filters as load increases. With a 10 kΩ load and 8.95 V input, I measured an input current of 9.26 mA, output current of 8.45 mA, and output voltage of -8.39 V.