I am getting all of the parts to construct the Collosalus and had a question about the power supply. Am planning on building the 9V version. Can I use a OneSpot or any other positive ground, negative tip power supply? Looking at the schematic and wiring guide, it appears that the tip is positive. The 18V power supply for the MXR 117 shows negative tip and positive sleeve.
Thanks
I think maybe the problem is that the jack on the schematic resembles a 3.5mm mono jack. Really they're expecting you to use a 2.1mm barrel jack, where the centre is negative (i.e. like the One Spot or the standard Boss PSA power adaptor). You are indeed OK using the OneSpot (provided you hook up the wires correctly of course :) ).
Also, thanks to you, I just learned that the centre of a barrel jack is indeed referred to as the "tip". I've always heard those power supplies referred to by the "centre" polarity, i.e. a centre-negative or centre-positive plug. So, you know, thanks :)
Sorry to say in 3 posts what could have been said in 1, but just a word of advice: don't substitute a TC1044S charge pump for the LT1054 in the schematic. That's a recipe for clock noise because it happens to heterodyne with the clock frequency driving the delay chip.
Thanks for the reply. So I should hook up the tip to the - pad and the sleeve/barrel to the + pad or as shown on the wiring guide? I will be using the LT1054 for the charge pump.
Aha, figured it out. Tip (negative) goes to the - pad and the ring/barrel (positive) goes to the + pad. Been almost a year since I built my last pedal so I had to go back and re-learn everything I forgot. Can't wait to get this built as I hope this will replace my Chorus and tremolo pedals, freeing up space on my pedal board.
Received most of the parts yesterday and screwed up on the 470uf e-cap. The one I ordered is 25mm L by 16mm Dia. and will not fit on the board. I can get one at the local Fry's electronics that is only 10mm Dia and 20mm Length but only in 16V. Their 25V e-cap is a little larger with a diameter is 13mm. Will the 16V work? If not I will have to order a smaller one from Mouser ($8 to ship!) or should I mount it off board with shrink wrap on the leads?
You shouldn't use the 16V capacitor, as it will see a typical voltage of 18V. Mounting it offboard is probably your best bet. Or, you could install it on the flip side of the board (make sure you don't reverse the legs doing so though) horizontally, if it'll fit that way.
Thanks, that's what I thought. I will go ahead and place another order with Mouser for the smaller cap along with a few other things to spread out the shipping costs. Will use the large cap while setting the trim levels etc. and pop the other one in when it comes in. Mouser is usually pretty quick on their orders.
Well, it's up and running on the first try. One of the more complicated pedals I have built but if you check and double check everything it should turn out alright. Love the sound and it sounds everybit as good as the original 117. Changed C22 to 51pf (from 47pf) and am getting a little more sweep without any extraneous noise. If I build another one of these I will definitely order the smallest capacitors I can find as I had a couple of issues fitting everything on the board. The Kemet film caps are great due to their size and shape and they fit side by side on the board. Found smaller NIchicon e-caps at Mouser as well.