A voltage doubler is a handy thing to have if you're making or modifying guitar pedals and for other projects. 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 twice 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 kit and there's a video of the assembly process below. This item includes the printed circuit board as well as the following components:

• 2x 10Ω 1/4W 5% resistors
• 5x 100µF 16V 20% capacitors
• 1x TC7660H charge pump IC

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 which is included with the kit, the frequency of oscillation should be around 120kHz - well outside the normal audio frequency range. Even so, I've included filtering on both the input and output in this design. Efficiency is less than 100% and there is some additional voltage drop through the filters as load increases. With a 10kΩ load and 8.95V input, I measured an input current of 9.26mA, output current of 8.45mA, and output voltage of -8.39V.