Electrolytic Cap for LFO

[lapsteelman]

I've built a circuit that uses an LFO like the one here  http://www.luciferstrip.com/fuzz/pitchpirate.jpg

I've read recently that it's bad design practice to use a polarized electrolytic for C13...  I've built several of these LFO's for other pedals, it works great.

Should I swap these out for NP caps or let it ride?...am I risking premature failure?  Doug's been using these for a while now so I'm guessing it's not the end of the world.  Thoughts?

[amptramp]

I assume you are talking about C13, which should be bipolar.  1 µF is a small enough value that you could use a film capacitor but if you don't have the space for that, bipolar is the way to go.  Even with the limited current going through it, it may exhibit leakage after a while.

[bool]

You could also use a X7R type multilayer ceramic but you'd have to measure it before installing it. These type caps real value drifts with temperature and applied voltage but for a pedal they are probably acceptable.

These are usually small enough but ... all are not created equal.

[Kipper4]

You might try the old back to back electrolytics too.


http://2.bp.blogspot.com/-NnBwEIsYXl0/UdSZu3pCcnI/AAAAAAAABbA/ghWC7ohF65g/s567/Dual+Fading+LED+Alternating+On+Off+Opamp+LFO.gif

notice the lm324 LM358

[Fancy Lime]

Yeah, I would most definitely change that cap. An electrolytic may fail quickly or never when used in an oscillator, you just never know. There are box-design film caps that are hardly any bigger even at 1µF than your average electrolytic and cost well under 1 € or USD.

Andy