On 13/06/2011 02:13, Bob Ammerman wrote: > ----- Original Message ----- > From: "RussellMc" > To: "Microcontroller discussion list - Public." > Sent: Sunday, June 12, 2011 6:36 PM > Subject: Re: [EE] My very simple optical guitar tuner board - please > giveadvice > > >>> Purpose of the reservoir cap is to hold charge and deliver it >>> with more of a force than a weak battery could. > I am assuming that the tuner runs the LEDs continuously at the tuning > frequency while it is in use. If that is the case then there is no sense = in > using a really large cap. You only need one to hold enough charge for one > pulse of the LED. You certainly aren't likely to have one big enough to h= old > a charge through a whole tuning cycle, which I am guessing will be at lea= st > several seconds. > > -- Bob Ammerman > RAm Systems > It is to be noted that with a tuner, even one pulse at 1:10 duty can be=20 in the order of milliseconds at the lowest frequency. With mine the lowest frequency is around 16Hz (about the lowest audible)=20 so 1/16 =3D 62.5ms @1:10 duty =3D 6.25ms pulse length. This is assuming you keep the pulse length a ratio of the frequency and=20 not some standard length which is independent. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .