Jack Orman's pickup simulator build

[tootsMcgee]

http://www.muzique.com/lab/pickups.htm



I put this together last night with the bells and whistles suggested in the page (switchable center tap for "pickup" type selection, volume and tone knobs). It's messy and fragile. I haven't tacked down the transformer/inductor to keep it from moving.

I also added a 1/2W 470R resistor across power to function as a light load on my power bricks...literally the power supply does nothing in this circuit besides lighting the LED. I have a decent Dunlop brick that has almost no noise under any circumstance but also has some pretty sensitive overcurrent protection circuit that cuts out when I plug in a pedalboard with two huge electrolytics built in. I also have a cheapy Planet Wave adapter that has a high pitched whine under light load. I'm hoping this will load down the supply a bit. It should draw around 20mA and shed about 1/4W. Why yes, I could just buy another one, but I like experimenting.

Should the outer frame of the transformer be grounded? What about any of the secondary terminals?

This will be cool for repeatable testing/sound demos from known benchmark audio...

[Rob Strand]

Should the outer frame of the transformer be grounded? What about any of the secondary terminals?

In a closed metal enclosure it's not going to be critical.

If the transformer was more exposed then grounding the chassis and grounding *one* of the secondary windings (one side will often be better than the other) you could reduce noise pickup.   I always try stuff like that out.  Sort of like guitar pickups with grounded pole pieces and cavity shielding around the pickup - pretty obvious these things do make a difference in less the ideal environments.