GEO-Fex Spyder Pedal Power Supply

Projects > GEO-Fex Spyder Pedal Power Supply

RG Green of GEO-Fex (and Chief Engineer at Visual Sound Pedals) has engineered a simple way to build a pedal power supply that solves one of the most prevalent issues plaguing pedal-savvy guitarists: ground hum. The main underlying philosophy of the Spyder is transformer isolation of each pedal’s power supply- as opposed to most devices on the market, which have pedals sharing a common ground, thus inducing unwanted noise. There are two possible configuration options: the first is through a single transformer, with the primary connected to mains voltage. Multiple secondaries are connected their own full-wave rectified 9VDC power supplies, each powering an individual pedal. The other method uses multiple transformers, connected in parallel to mains voltage, each with their own power supply on the secondary. Furthermore, through use of adjustable regulators such as the LM317L, the DC output voltage can be slightly dropped to emulate a weak or dying battery, achieving a sound in some distortion pedals that many guitarists prefer to a clean regulated power supply.

Spyder Power Supply Features:

  • Ability to power up 8 pedals from one wall plug (can potentially be any number if mult.-transformer method is used)


  • $25 for Weber WPDLXFRMR-1 transformer (1 120v primary, 8 12v secondaries), or
  • $3.62/each for Xicon 41PG006 transformer (1 120v primary, 1 12v secondary)


More Information:

  • Complete project documentation can be found on Geo-Fex’s Spyder page


One thought on “GEO-Fex Spyder Pedal Power Supply

  1. Per the Geofex website (regarding the Spyder power supply):

    “April 10, 2015. This project has been up on geofex for fifteen years. I believe it was the origin for commercial many-output power supplies for pedalboards, and for the many dying battery simulators that are common in the DIY effects world. However, it does involve some risks. That warning is serious. In a couple of forums on the net I have seen some questions that have finally made me conclude that there are people coming into the DIY effects world that will ignore the warnings however they are worded. So, regretfully, I am removing the technical content from this article. “

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