Guitar Effects Pedal Power Supply

Let's Make Robots
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PS-01.jpg
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https://www.robotshop.com/letsmakerobots/files/PS-01.jpg

https://www.robotshop.com/letsmakerobots/files/PS-02.jpg

https://www.robotshop.com/letsmakerobots/files/PS-03.jpg

https://www.robotshop.com/letsmakerobots/files/PS-04.jpg

https://www.robotshop.com/letsmakerobots/files/Pedal_Board_01a.jpg

https://www.robotshop.com/letsmakerobots/files/Pedal_Board_02a.jpg

https://www.robotshop.com/letsmakerobots/files/Pedal_Board_03a.jpg

https://www.robotshop.com/letsmakerobots/files/Pedal_Board_04a.jpg

 

Abstract: I built a power supply (R.G. Keen's Guitar Effects Pedal Power Supply) as a gift; it is one of my first projects using the Valkyrie-clone CNC machine for PCB fabrication.  The Power Supply is a bow power supply, and the source is at http://www.geofex.com/Article_Folders/Spyder/Spyder.htm
One board has 6x basic regulators, another has 2x "Deluxe Regulators".  The resistors for "deluxe" are specified 240, 1.1k, a 500ohm trimpot and a 100ohm trimpot.  The 100 ohm trimpot must be capable of 0.5 Watt dissipation.

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The Xicon transformers (Mouser part #41PG006) are mounted seperately: the leads from the secondary coils go to the AC jumpers.  Each 4 DC outputs are connected to a DB-9 connector; the DB-9 connector attaches to four 2.1mmx5.5mm DC barrel jacks, negative pin, which connects to most effects pedals.

https://www.youtube.com/watch?v=nHmdzAsNSSE
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After making the board
After making the first trace, I figured I might need more isolation than one thin trace. Using the pcb_gcode_setup EagleCAD plugin again, I set it up to run a few more outlines around the board, then after it was traced, I ran the rotary tool around the traces to scrape off more of the copper (the trace etching bit did not remove all the copper). The updated pic shows there’s less likelihood of me accidentally shorting something.

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I think I figured out
I think I figured out why the traces tend to be too narrow – I set the milling bit size too small, so when it cuts, it cuts away more material than the gcode plug-in thought it would. Why would I have done that? Well, the GCODE plug-in won’t isolate close-together traces unless it thinks the machine can do it perfectly (if it doesn’t isolate them, they stay connected). To get around that I found that I could fiddle with the bit size (one user-specified variable) and trace isolation (two or more variable) settings until they isolated the traces. Unfortunately when the machine actually cut, it sometimes cut the traces pretty thin. (also the spindle/z-axis can wiggle a bit, which is effectively like having uncorrectable backlash). Next time I cut, I’ll be trying to set the bit thickness as big as I can get away with while still isolating my traces.