Not on the web site... I would have to take that one too! John Ferrell 6241 Phillippi Rd Julian NC 27283 Phone: (336)685-9606 Dixie Competition Products NSRCA 479 AMA 4190 W8CCW "My Competition is Not My Enemy" ----- Original Message ----- From: "Larry Williams" To: Sent: Friday, August 10, 2001 7:55 PM Subject: Re: [PIC]: Building a "counter" w/PIC16F628 > If you need a decent freq counter, check radio shack. They have on that is discontinued and is now reduced down to $49.95. I bought one just because it was cheap( even cheaper since my wife gets 25% off) and today it got its first use on top of a 380 foot tower checking freqs in a tower top microwave transceiver. Good to either 1.3 or 1.6 ghz. Don't remember for sure. Has seperate switch position for ttl level / rf > > > > From: Dan Michaels > > Date: 2001/08/10 Fri AM 11:44:40 EDT > > To: PICLIST@MITVMA.MIT.EDU > > Subject: Re: [PIC]: Building a "counter" w/PIC16F628 > > > > Mike, > > > > The problem here is you are not simply dipping a grid, you > > are interfacing a 200+ Mhz tiny RF signal to a digital chip. > > That is why I mentioned the real crux of this project is in > > "RF design/layout/matching/amplification/sensing/etc" - taking > > that tiny signal and converting successfully to 0-5v. > > > > Once you have picked up and amplified the "sine", then you > > can use an analog prescaler and/or schmitt trigger to square > > up for presentation to the PIC. The PIC can probably accept a > > sinewave ok, as long as it is large enough [about +/-2v], shifted > > into the range 0-5v, and slews fast enough so that noise doesn't > > cause false counts. > > > > AN592 talks about using Timer0 of the '84 for counting. I mentioned > > it mainly for reference. The '628 is probably too new to find much > > specifically about using it. However, the Timer1 module is the same > > as on the '74/'76/'77/'874/'876/'877, so you can look at those > > chips. > > > > Also, I don't know anything about the el cheapo programmer and > > the '628. Again, the '628 is so new, not everything out there > > supports it. > > > > - dan > > =============== > > > > > > At 10:43 PM 8/9/01 -0000, you wrote: > > >Dan, > > > On the oscillator part of the circuit, it is too easy actually. The > > >user of the Grid Dip Oscillator adjusts a knob to vary the frequency of the > > >circuit. As the frequency is adjusted the current going through the meter > > >will change if it matches the resonant circuit by dipping. These hand held > > >pieces of test equipment have been around for over 60years to my knowledge > > >and are beautiful in their simplicity. They origionally consisted of a > > >single vacuum tube that had the plug in coils. The tricky part of the > > >origional design was that the coils had to be wound so that the readout on > > >the printed dial matched the actual frequency within reason. In this > > >application, that is totally unimportant as the digital frequency counter > > >does the job. Therefore, I can use handwound coils that vary considerably > > >from each unit produced just as long as the frequency readout is correct, > > >everything is A OK. > > > A 180mhz digital readout would really be perfect for me. > > > > > >1st question-do you think I'll be able to use the sine wave into the > > >counter, or would I need to "shape it" for the PIC?? > > > > > >2nd question-from what you described origionally, the 74AC74 would be great. > > >I'm not looking for 1hz resolution or anything. As a matter of fact 10khz > > >or 1Khz resolution would be great! Do you agree, or do you still feel that a > > >prescaler is better? > > > > > >3rd question-is the AN592 related to the 16F84, or PIC16F628? > > > > > >4th question-do you think the "el cheapo" programmer from Myke Predko's book > > >will work with the PIC16F628 if I go that route? > > > > > >Thanks again/regards, > > >Mike > > >----- Original Message ----- > > >From: "Dan Michaels" > > >To: "Mike Kendall" > > >Sent: Friday, August 10, 2001 3:15 AM > > >Subject: Re: [PIC]: Building a "counter" w/PIC16F628 > > > > > > > > >> Mike Kendall wrote: > > >> >Dan, > > >> > Yes, I will be counting analog signals out of an oscillator circuit. > > >> >These will/should be a clean sine wave. I will describe my project. I > > >was > > >> >disgusted with the high price of simple analog grid dip oscillators. The > > >3 > > >> >and 4 decade old units were going quite high and the new units were > > >around > > >> >100 bucks for an analog meter face type unit with little accuracy. > > >> ........... > > >> Ideally, the circuit > > >> >will work up to 250mhz, but up to 180mhz would be outstanding as it would > > >> >cover the marine band, 2meter ham band and down to hopefully 1.8 mhz > > >(even > > >> >lower would be better). > > >> .......... > > >> > > >> > > >> Mike, from what you describe, the PIC part of this should be fairly > > >> easy. Check the appnote, AN592, that I mentioned for prelim info. > > >> Other Mchp appnotes discuss interfacing LEDs/LCDs - AN590, AN529, > > >> AN563. > > >> > > >> The harder part looks like the analog front end to 250 Mhz. Does > > >> sound like a prescaler chip is in order - plus of course correct > > >> RF design/layout/matching/amplification/sensing/etc. This part > > >> requires a lot more savvy, I think, than writing a few lines of > > >> PIC code. A 16:1 or 32:1 prescaler should put you into the correct > > >> range for the PIC. > > >> > > >> good luck, > > >> - dan > > >> ============= > > >> > > > > > > > > > > > > > -- > > http://www.piclist.com hint: PICList Posts must start with ONE topic: > > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > > > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics