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Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
I CANNOT find anything. I dont know enough about logic ic's to find much of anything, Countless hours spent searching.
Goal:
Need a very stable 4Mhz square wave.
Feed crystal oscillator output into logic ic get square wave out... Does anyone know what chip i would beed to achieve that ? Would i need a buffer before? I plan on feeding the signal source into this intern to switch a MOSFET
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
Sulaiman wrote ...
why not use a crystal oscillator? e.g.
Thats what I want to do since I need the accuracy the crystal supplies. Maybe I dont fully know what that crystal you linked does... Do I supply a voltage and It generates 4MHz? Doesn't it need to be buffered before going into the gate drive or at least amplified ?
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
The crystal oscillator that I linked to is a 3.3 v supply version, not a good choice to drive the gate driver ICs a 5v squarewave output crystal oscillator is more suitable, e.g.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
jdub's circuit is for using a bare 2-terminal crystal (passive component). Change the crystal to change the frequency. Sulaiman pointed to some crystal oscillator components, which are easier to use. Connect appropriate power voltage (3.3 or 5 volts) and get a corresponding logic signal out. In both cases the frequency is fixed. Worst case frequency error of +/- 100 ppm (0.01%) is a pretty loose tolerance for crystal controlled oscillators.
Your 74LS624 is a voltage controlled oscillator chip. VCO, not VCXO. No crystal, and you can tune the frequency over a substantial range. How are you planning to measure the frequency, if you don't have an oscilloscope? You could divide it down into the audible range (e.g. with one CD4040 or CD4060) and listen with headphones or a small loudspeaker. Instrument-tuning apps on smartphones can convert a tone into a number. Or adapt an old auto service dwellmeter/tachometer, which I could send you for cost of postage.
It's time you learned more about logic IC's. Jump on in; they don't bite. Get a plug-in breadboard to play with -- apparently as popular now as they were decades ago. There are other forums to learn at. Logic signal input/output compatibility can be checked by studying the DC specifications section of the data sheets. Before the Internet, people used to keep things called data books for that purpose.
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
klugesmith wrote ...
jdub's circuit is for using a bare 2-terminal crystal (passive component). Change the crystal to change the frequency. Sulaiman pointed to some crystal oscillator components, which are easier to use. Connect appropriate power voltage (3.3 or 5 volts) and get a corresponding logic signal out. In both cases the frequency is fixed. Worst case frequency error of +/- 100 ppm (0.01%) is a pretty loose tolerance for crystal controlled oscillators.
Your 74LS624 is a voltage controlled oscillator chip. VCO, not VCXO. No crystal, and you can tune the frequency over a substantial range. How are you planning to measure the frequency, if you don't have an oscilloscope? You could divide it down into the audible range (e.g. with one CD4040 or CD4060) and listen with headphones or a small loudspeaker. Instrument-tuning apps on smartphones can convert a tone into a number. Or adapt an old auto service dwellmeter/tachometer, which I could send you for cost of postage.
It's time you learned more about logic IC's. Jump on in; they don't bite. Get a plug-in breadboard to play with -- apparently as popular now as they were decades ago. There are other forums to learn at. Logic signal input/output compatibility can be checked by studying the DC specifications section of the data sheets. Before the Internet, people used to keep things called data books for that purpose.
Man this place has really gone down hill and you are a perfect example. Frist of all I do own a scope! secondly, I am over my head and I dont know very much about any of this class e RF amps but thats how you learn new things and this is a place to ask quesions. Im challanging myself and come here for support and this is what I get "Get a plug-in breadboard to play with -- apparently as popular now as they were decades ago. There are other forums to learn at." are you kidding me ?!?!
I have looked at the data sheets for the provided schematics and I have been doing a ton of research but I am by know means an expert.
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4Mhz square wave generator
