How can I get a quartz crystal to make square waves at 4.096MHz? So far I have the 4.096MHz quartz crystal and this schematic I saw:
Where can you find an amplifier with a single input and what voltage should I use?
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You can make a Pierce Oscillator similar to that shown in your question:
The "single input amplifier" is usually a simple CMOS inverting gate, like the 74HC7404 (6 inverters in one package), SN74HC14D (single inverter) or similar.
Voltage can be something within the operating range of the IC, such as 5V. You may need to add a series resistor to limit the crystal drive (you need to check the crystal datasheet for manufacturer recommendations)
Here is a circuit with typical component values:
Note the series R mentioned above. The above came from this Fairchild App Note which goes into some detail on the design process.
You can only pull the frequency of a crystal oscillator a very small amount, so you will need a 4.096MHz crystal. Either that or you will need to use something else such as a PLL.
You can use an op amp in your circuit, ore use a 555 to generate square weaves
or do something like this:
Generally Xtals below 30MHz are fundamental parallel mode resonance like LC expect Q is 3K and high impedance 180deg phase shift at resonance. THis means you need negative feedback using an inverter not a series mode with a non-inverter. Try both buffered x1000 gain and unbuffered x10 gain inverter CMOS chips and ensure spurious harmonic oscillator modes are avoided.The Xtal Q has enough gain with CMOS gain of 10x to get a square wave when feedback R is high Z.
Let Rf = 1~10 MΩ to self bias input to Vcc/2 let Rs = 10kΩ and C1 = 30~47pF or so. Let C2 = 100~1000pF in series with Varicap cathode while anode is to ground for reverse bias V vs cap control. Choose 0~12Vdc control range for varicap (or more) and select C1 to tune centre F.
I know this is a lot to take in a short paragraph so ask a Q? or read up on parallel VCXO's.
Here is a simple reference to appreciate Crystals more.