I'm not using arduino yet to supply the voltage. For now, I'm merely using a battery pack. It's supposed to be emitting a tone; however, nothing is coming out of the speaker except a crackly sound. I'm using an 8 ohm speaker, and a 200K instead of a 220K resistor. Anybody know what's wrong? Could it have to do with the wiring? I'm pretty sure everything is correct—except I'm not sure if I wired pin 5 correctly. Does anybody know how to wire pin 5?
Thanks GrumpyMike, I fixed that…I have another schematic that shows a resistor with an arrow next to it, and I was wondering what that symbol stood for. It still wasn't working, but then I switched up the 0.01uF capacitor with a 10uF capacitor and suddenly it worked fine.
However, I'd like to be able to produce more variation in the pitch/experiment with it and try to produce higher pitches, since the pitch is really low. How can I do that?
I'm guessing that there is a relationship between the frequency of the sound waves and the resistance/capacitance in my circuit. What is this relationship? If not, then what controls the sound frequency?
Read the 555 datasheet ahhreeyell , there are graphs showing possible ranges, and formulas that you can populate with R & C values. You can make an excel spreadsheet to do the math, then play with different standard values to get the outcome you want. OR, rewrite the expression in excel to start with the frequency and fixed values, and determine the resistor (or capacitor) needed.
I have another schematic that shows a resistor with an arrow next to it,
There is a pot on tat circuit it is R2, in that case the wiper is connected to one end and the thing acts as a variable resistor, as opposed to a potential divider.
but then I switched up the 0.01uF capacitor with a 10uF capacitor and suddenly it worked fine.
Then I think you might have the value of R3 not quite correct as well.
(R2 + R3) * C1 controls the charge time and R3 * C1 controls the discharge time, so the time period of the wave is simply the charge time plus the discharge time. Note that the units of resistance times the units of capacitance equals the units of time. It made a great little derivation excise for my students.
However this is modified by the variable input voltage introducing a modifier on the two times but for the sake of calculations assume this is one (that is ignore it).
VCOs are present in nearly all high performance microprocessors! The internal clock is generated from an external crystal via a phase-locked-loop (which has a VCO at its heart). The reason being that crystals above about 30MHz are overtone crystals and hard to drive reliably to the correct overtone without manual adjustment. However modern CMOS processes can clock at many GHz since the FETs switch in a few picoseconds.
Solution: external low frequency crystal drives PLL on chip.
