Charge Pump Whining

[Pavlos]

I've finally got round to building some charge pumps http://3.bp.blogspot.com/-iwq-E6fhOO8/VoxNZp9DNnI/AAAAAAAAAK8/Gvbr4jzcGNs/s1600/Switchable%2BOnboard%2BPower%2BV3.pngto test out how much of a difference 18V (Ish) makes to my builds. I'm getting pretty much spot on 9v and 18v from the appropriate outputs using a fresh 9v battery, however with the 9v output I'm getting a fairly quiet but still noticable constant whine in the background, which with the 18v output becomes very noticable, sounds rather reminiscant of the old TV 'test tone' I've checked for correct/faulty components and orientation (All good and suitable voltages for the caps) and to make sure that the cuts are all clean, made sure that all solder joints are good, knifed between the tracks to make sure there are no rogue shorts and also tried a few 7660S just in case of a dud chip, all exactly the same though. Also re-routing the wiring did make a slight difference but only from extremely obtrusive to very obtrusive With everything loooking like it should (Barring glaring errors and total stupidity on my part) be ok with the build, one obvious reason that springs to mind that might be a cause is that I'm testing on a breadboard rather than boxed, any thoughts and help would be very much appreciated I also built the NE555 version https://3.bp.blogspot.com/-oPVvF9gE80U/VyLZWmTNF5I/AAAAAAAAAUU/p_ao8ImXqv4TvnFrynxv7hkgeGKXYwnSwCLcB/s400/Switchable%2BOnboard%2BPower.png which only put out about 16.5v was, as far as I could tell absolutely silent. Major downside to this one though is size, bigger board, nore componebts and those higher value electrolytic caps are quite bulky in comparison

[Beaker]

I've built this a few times, and it has been totally silent - as long as you use 7660S chips. It will whine if you use 7660.

Post some pics it may help.

Maybe you are trying it on a pedal that just does not like this circuit? I've not heard of that happening, but anythings possible I guess.

[Pavlos]

Thanks for the quick reply Beaker. I'll try to get some pics sorted, but in the mean time, the chips are 7660SCPAZ from dasmusikding, and were bought specifically because as you mention, the S variant is reccomended due to the basic 7660 being prone to whining. I did wonder if it was maybe a compatability issue (Reading the forums is an excellant source of useful information and handy fault finding tips) so double checked with other builds just in case, but got the same result every time........ so at least whatever the problem is then it probably applies to all three of the 7660 charge pumps I've built!.........or perhaps this is my nemesis lol

[Travis]

I've had a lot of issues with the ICL7660S whining. Not sure if they are defective ICs, maybe an issue with the electros used for filtering, or maybe some circuits are more prone to noise issues with these charge pumps.

I've used them successfully plenty of times but have had issues that wouldn't go away as well

[Pavlos]

and here are the pics

left hand boards is built exactly as per the layout, the two on the right have one of the diodes and couple of the caps moved slightly so as to fit the board a little bit more neatly, all connections still as per the layout though.

[Pavlos]

Thanks Travis, that is both heartening and dishearthening lol, perhaps it is akin to the PT2399 issues, sensitive to things being 'just so' sometimes they play a bit more nicely, sometimes they don't.......and yep, like many others I have some PT2399 builds that just refuse to work (So far that is, they inhabit the come back to it later pile, including everyones favourite litlle a****) while others have worked perfectly first time (Gravity wave/sea machine)