PLL Breadboard Issues
in [Design]
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From: Chris on 28 Feb 2010 10:25 I bread boarded my PLL yesterday. I was able to get it to lock just fine on a multivibrator running at 33Hz. I was able to solve the jitter problem by using a very large value for C1 (1000u). However, when I attached my cameras to the loop, (one running at 22.2fps and the other running at 25fps) the loop would lock at a frequency slightly above the camera speed ~39Hz. The camera has a contact that closes ~5ms every frame advance. I tried using the contact to pull to ground, and to pull to rail. I got the same result either way. Any suggestions? Thanks, Chris Maness
From: Jamie on 28 Feb 2010 10:57 Chris wrote: > I bread boarded my PLL yesterday. I was able to get it to lock just > fine on a multivibrator running at 33Hz. I was able to solve the > jitter problem by using a very large value for C1 (1000u). However, > when I attached my cameras to the loop, (one running at 22.2fps and > the other running at 25fps) the loop would lock at a frequency > slightly above the camera speed ~39Hz. The camera has a contact that > closes ~5ms every frame advance. I tried using the contact to pull to > ground, and to pull to rail. I got the same result either way. Any > suggestions? > > Thanks, > Chris Maness Two camera's in line with different fps ? how do you expect it to lock properly?
From: MooseFET on 28 Feb 2010 10:39 On Feb 28, 7:25 am, Chris <christopher.man...(a)gmail.com> wrote: > I bread boarded my PLL yesterday. I was able to get it to lock just > fine on a multivibrator running at 33Hz. I was able to solve the > jitter problem by using a very large value for C1 (1000u). However, > when I attached my cameras to the loop, (one running at 22.2fps and > the other running at 25fps) the loop would lock at a frequency > slightly above the camera speed ~39Hz. The camera has a contact that > closes ~5ms every frame advance. I tried using the contact to pull to > ground, and to pull to rail. I got the same result either way. Any > suggestions? > > Thanks, > Chris Maness Which phase detector are you using? An XOR can lock to ratios of numbers of the input signal like 2/3 A tristate phase frequency comparator is bothered by contact bounce.
From: Chris on 28 Feb 2010 11:23 On Feb 28, 7:39 am, MooseFET <kensm...(a)rahul.net> wrote: > On Feb 28, 7:25 am, Chris <christopher.man...(a)gmail.com> wrote: > > > I bread boarded my PLL yesterday. I was able to get it to lock just > > fine on a multivibrator running at 33Hz. I was able to solve the > > jitter problem by using a very large value for C1 (1000u). However, > > when I attached my cameras to the loop, (one running at 22.2fps and > > the other running at 25fps) the loop would lock at a frequency > > slightly above the camera speed ~39Hz. The camera has a contact that > > closes ~5ms every frame advance. I tried using the contact to pull to > > ground, and to pull to rail. I got the same result either way. Any > > suggestions? > > > Thanks, > > Chris Maness > > Which phase detector are you using? > > An XOR can lock to ratios of numbers of the input signal like 2/3 > > A tristate phase frequency comparator is bothered by contact bounce. I am using Comparator II for edge detection. Yes, there might be some bounce. How can I clean up the signal? Also, with the 33Hz multivibe there is a extremely low frequency FM'ing ~1/2Hz. Should I try a smaller C2 in combination with a bigger R3? Correction: the 1000u is C2. Thanks, Chris Maness
From: Chris on 28 Feb 2010 11:29
On Feb 28, 7:57 am, Jamie <jamie_ka1lpa_not_valid_after_ka1l...(a)charter.net> wrote: > Chris wrote: > > I bread boarded my PLL yesterday. I was able to get it to lock just > > fine on a multivibrator running at 33Hz. I was able to solve the > > jitter problem by using a very large value for C1 (1000u). However, > > when I attached my cameras to the loop, (one running at 22.2fps and > > the other running at 25fps) the loop would lock at a frequency > > slightly above the camera speed ~39Hz. The camera has a contact that > > closes ~5ms every frame advance. I tried using the contact to pull to > > ground, and to pull to rail. I got the same result either way. Any > > suggestions? > > > Thanks, > > Chris Maness > > Two camera's in line with different fps ? > how do you expect it to lock properly? No, I have two cameras that I would use at different times. Not in series. I am designing the circuit because most small gauge film cameras run "wild" and I am designing the tape to slave off of the "wild" cameras at the expense of some pitch shifting. The design will ultimately convert the ~24Hz pulses to ~60Hz pulses with a proportional error. When the film is scanned in to a frame accurate file @ exactly 24fps, the tape (perforated tape with a film base) can be played back at exactly 24fps from a crystal reference. The end product is lip sync sound. Thanks, Chris Maness |