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What about using an analog pin to sample an audio signal? I'm envisioning a circuit that would offset the +/- signal so that it exists only in positive voltage, sampling that signal with an analog pin, and outputting it through PWM. It seems like this could be possible with the teensy. I don't...

What capabilities does the teensy have for sampling audio input? Can it sample an audio signal and output it through PWM? Can it sample two audio signals, mix them, and output the signal as PWM? I've looked through the board and haven't found anything that appeals to my novice understanding...

I don't have the hardware yet, but here's the code I've been developing. The triac is triggered at the first zero-crossing and remains on until a specified amount of half-cycles have completed, at which point the voltage is dropped and the triac is turned off. After another specified amount of...

Instead of analyzing the audio track directly and then converting it to visuals, create an info file for each song that you want to visualize--a file that contains maybe tempo information, feel changes--just a few simple things that will make the visualizer respond more realistically to the...

Another thing I want to try is "tuning" the interference. I think with a little experimentation I will be able to control the harmonics of the interference and tune it to musical semitones. If what I'm playing through the speakers is in the key of C, I'll just set the interference to produce a...

I see what you're saying. I'll be sending the pulses in relationship to zero-points so it won't be an issue. By smoother I meant there will be more unique points at which the phase is chopped if the pulse isn't a multiple of 60--but your point is taken: there will be a much different outcome if...

So a single pulse to the triac will turn it on until the end of the half-cycle (until another zero-point is reached)? In other words, you don't need to maintain the pulse for the entire half-cycle, you just need to pulse it at the moment you want the triac to turn on, and it will stay on until...

I'm curious to know how this interference propagates from a dimmer switch. I'm guessing it is transmitted backwards through the AC supply and affects anything using the same AC source? So it is the AC to DC conversion that would have to filter this interference somehow? Quality DC might a good...

What I'm trying to avoid is this kind of phase chopping, which is what causes noise interference in the speakers: (Click image to see animation) But as you suggested, if this is only happening at 11hz, noise interference won't be as big of an issue. Am I correct? In other words, instead of...

Unfortunately due to the fact that this thing was for some reason built to double as a cruise ship anchor, a smaller motor will not work. The whole thing weighs about 30 pounds--all to drive two 3" speaker on a rotation of diameter of about 1.75'. It came out of a console organ from the '50s.

Unfortunately I think it's an asynchronous motor. I've tried phase cutting with a simple dimmer designed for lighting and it works, except that it produces a considerable amount of noise interference in the speakers. What about using a relay to momentarily turn on and off the current to the...

I couldn't find the model number for this motor online... that's why I included the pictures. Is it possible to tell what type of motor it is just by looking at it?

(the motor pictured above has a diameter of about 3.25 inches) I have an AC motor driving a rotating speaker. If I vary the frequency of the AC input, will this vary the speed of the motor? With these two devices, it seems I can control the frequency of the AC input...

It isn't a circuit designed to test resistance.... It's a way to test which of the gates (A. or B.) is open under the less-than-ideal circumstance when their paths are be shorted by a conductor.

https://www.sparkfun.com/products/8680 I need something like this, minus the wiper layer. I don't think it would be possible to modify this one by removing the wiper layer.

Does anybody sell standalone "resistive strips", like those found in potentiometers? I'm looking for about 4 or 6 inches of a resistive strip--like something found in a pot, but in a linear strip (just the resistive material, not the wiper or casing).

Ultimately I'll be getting into audio experimentation (I've got an idea involving a hall effect sensor and a rotating Leslie speaker), but right now I'm just trying to get a grasp on basic circuit design and theory. Circuit timing is something I'm interested in and that's where the design above...

I'm not quite sure yet, all I know now is that they'll need to be fast. Here's the abstract for the design I'm working on: http://forum.pjrc.com/threads/23702-Delayed-switch-circuit

Abstract: if switch "A" is on and switch "B" is off, a current of +3.3V would reach Circuit A before it reaches Circuit B because of the delay caused by the slowed flow of the +3.3V through the poor conductor. By design, Circuit A would then tell Circuit B to close its gate between its input and...

+3.3V. Nothing outside of what the Teensy provides, i.e., no external power. It's switching a digitalWrite(HIGH) load to ground. I tested the TIP120 and the fastest I could get it to switch was around 20µs.

I'm looking for a transistor that is capable of acting as a switch to ground--and I need it to be fast. My current design calls for an NPN transistor to act as an ON/OFF switch, controlled by a digital pin on the teensy using digitalWrite(HIGH/LOW). I need this transistor to be as fast as...

Sorry, I found the answer to this question here. Code to enable internal pulldown resistor: *portConfigRegister(pin) = PORT_PCR_MUX(1) | PORT_PCR_PE;

That makes sense. If I understand correctly, there is only built-in functionality for a pullup resistor, and not a pulldown? In other words, I'll have to manually connect pin3 to ground with a resistor? (and remove "pinMode(pin3, INPUT_PULLUP)")

Two digital outputs connected to one digital input I'm trying to understand digital I/O functionality. I want to connect pin1 and pin2, both in OUTPUT mode, to pin3, which is in INPUT_PULLUP mode. With pin1 and pin2 set to write LOW, pin3 will read 0. With pin1 set to LOW and pin2 set to HIGH...

Paul, thanks for the time you put into answering questions so thoroughly. This is much appreciated.

I just tested an LM324 and it works well with +3.3V to power rail, no issues with voltages below 0.7V. Analog pins are giving very smooth and accurate readings. I can't be thankful enough for the help I've been given. I do have a question about the amplification ratio of R2/R1. Right now I...

Thanks for the help. Both designs work with -3v and +9v connected to the opamp power rails. I was not able to experiment with precise timing in regards to C1 and R3 because I have a cheap/slow voltmeter. I can verify, though, that the voltage was spiking and gradually decaying when a string was...

I'm developing software to interact with the plucking of a string on an electric guitar. I've decided to use the teensy 3.0 as an interface between the software and the guitar. Here's what I need from the teensy: I need a reliable stream of data representing the plucking of a string and its...