24Hz to 60Hz PLL?
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From: Robert Baer on 13 Feb 2010 00:09 Chris wrote: > I need to make a PLL that slaves to a 24Hz square wave. The output of > the loop would be a 60Hz square wave. Any CMOS level chips that would > be good for this? I understand that I would need to divide by a > decimal value of 2.5 for the loop. > > Thanks, > Chris Maness Better yet, multiply by 5 and divide by 2.
From: Chris on 13 Feb 2010 10:16 On Feb 12, 3:21 pm, Fred Bartoli <" "> wrote: > Chris a écrit : > > > I need to make a PLL that slaves to a 24Hz square wave. The output of > > the loop would be a 60Hz square wave. Any CMOS level chips that would > > be good for this? I understand that I would need to divide by a > > decimal value of 2.5 for the loop. > > PLLs a those low frequencies are real slow if you need some 'jitter > free' output. > > Square waves have only odd harmonics. You could square up your 24 Hz, > apply it to a narrow 120Hz BPF, then divide by two. > > -- > Thanks, > Fred. The 24Hz is square. What would I use for a BP filter at such a LF without having a very large inductor? Chris
From: Fred Bartoli on 13 Feb 2010 10:37 Chris a �crit : > On Feb 12, 3:21 pm, Fred Bartoli <" "> wrote: >> Chris a �crit : >> >>> I need to make a PLL that slaves to a 24Hz square wave. The output of >>> the loop would be a 60Hz square wave. Any CMOS level chips that would >>> be good for this? I understand that I would need to divide by a >>> decimal value of 2.5 for the loop. >> PLLs a those low frequencies are real slow if you need some 'jitter >> free' output. >> >> Square waves have only odd harmonics. You could square up your 24 Hz, >> apply it to a narrow 120Hz BPF, then divide by two. >> >> -- >> Thanks, >> Fred. > > The 24Hz is square. What would I use for a BP filter at such a LF > without having a very large inductor? > > Chris Make that an active filter. Only Rs and Cs, and at that low frequency, any opamp will nicely do. -- Thanks, Fred.
From: Chris on 13 Feb 2010 11:15 On Feb 12, 9:09 pm, Robert Baer <robertb...(a)localnet.com> wrote: > Chris wrote: > > I need to make a PLL that slaves to a 24Hz square wave. The output of > > the loop would be a 60Hz square wave. Any CMOS level chips that would > > be good for this? I understand that I would need to divide by a > > decimal value of 2.5 for the loop. > > > Thanks, > > Chris Maness > > Better yet, multiply by 5 and divide by 2. By dividing in the loop -- you are multiplying by 5. That is what I meant. The sum effect of the dividing is multiplying. How much jitter would the combo that I put together have? I can accept a lock time of a few cycles, I can accept jitter if it only effects the pulse width and it is not too bad. As far as the PIC, I have not programmed one before, and I have no clue on where to start. I can do basic, and some bash script, but I have never used anything like assembler. I was hoping to order a few chips from digikey, wire them together, and be done with it. If using a PIC is fairly easy for a n00b, then I would be willing to look into it. Thanks, Chris
From: Vladimir Vassilevsky on 13 Feb 2010 11:20
MooseFET wrote: > On Feb 12, 3:01 pm, Vladimir Vassilevsky <nos...(a)nowhere.com> wrote: > >>Chris wrote: >> >>>I need to make a PLL that slaves to a 24Hz square wave. The output of >>>the loop would be a 60Hz square wave. Any CMOS level chips that would >>>be good for this? I understand that I would need to divide by a >>>decimal value of 2.5 for the loop. >> >>Use a PIC. >> > > No, the 8051 is the right processor for this. Personally I despise PICs. However PIC became a generic word for any small microcontroller. Once a customer asked me if I work with PIC controllers made by AVR company. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com |