A street busker is someone who plays hand cranked organ grinder music and solicits donations. I have a modern version of a hand cranked organ that I would like to power with arduino circuits using an sd card for the music. I need to be able to turn a hand crank and then the music comes out to powered speakers. When the hand crank stops the music stops. This project is to solicit donations for veteran oriented non-profit groups that I support. Any help would be greatly appreciated. This is a worthwile cause.
Your intentions are commendable. Arduino’s are not in my knowledge base. Sparkfun may kick me out now for admitting that. Is the Arduino flashing LED’s on the box sync’ed to the music or what is its main purpose?
From what I understand you have all the components in what you are doing but looking for a method that switches the sound ON only when the organ crank is moving?
The most direct method I think would be a sound switch between the MP3 player line level output converted to a single-channel then to the amplifier. You cannot just flip a switch, as a pop in the sound might be heard. I know how to overcome the pop but detecting the crank movement effectively is the real trick.
You may have been using a toggle switch that your other hand flips. Tell me if I have misunderstood your need. Not having a visual of the crank in box to know what there is to work with now limits further thought. If the internal shaft was turning a small 3v dc motor the impulses off the brush contacts could be used to trigger a one-shot 555 to turn the sound On as long as there is movement, others may add to your idea?
The simplest way I can think of to accomplish this is to use the grinder to control play/pause on the MP3 player.
I built a prototype control for an MP3 player used in magic shows that operated the play/pause control. The client I built it for used a player that he had customized to his requirements because he is reselling them, but an off the shelf MP3 player would work fine. You could do something similar whereby a sensor on the grinder handle can be read and triggers the play input when it starts turning and triggers it again to pause when it stops. It’s a pretty simple behavior.
It may seem simpler to control on/off with the grinder handle, but that requires a player that starts playing when powered up and those are not as common.
UChip I like that rotary encoder so let us forget my dc motor idea. I picture the crank shaft being 1/2" with an end that might allow a knob for the encoder to be secured to with something like epoxy but heat shrink tubing might be better for flexibility.
All of your replies are very encouraging. I do have a background in electronics, however, I have no experience with arduino, so I am looking for a mentor.
The OP knows electronics so this approach should not need much of a learning curve. Most of my designs use a 555 somewhere; it is a sport in itself. If an Arduino is used you still need most of the components in this design.
I do not use computer modeling rather sketch out my thoughts and breadboard. The graphic shows more clearly my original idea using a 555 switch. The circuit could use some polish I am sure, timing adjustment? What type of Mechanical Pulse generator interface?
Using the VTCVL4 Vactrol has a “natural” fade out when turning the sound off, not so abrupt. Four AA batteries could last over a year “not” needing to be turned off using this basic circuit.
C3 2200uf adds to the fade out effect but not needed. I have a concern about latch-up?
I have no programming experience, which is my misfortune. I think I have a basic understanding of your circuit and it looks great. I think a rotary encoder would work fine. any idea of what kind of rep rate I would need?
My design avoids any programming. Using a TLC555 chip is an excellent way to learn and can be wired up on one of those white proto boards. Just plug things in. Using batteries is safe so go for it and see what happens. The Vactrol can be temporarily replaced with a LED for an indicator using the right side connections. LED On = Sound On. If you get the logic of the design making sense and working properly post a picture of your construction here. Then I will ride into town and mail you the Vactrol at no cost (free). As a hobbyist and parts hoarder I have loads of stuff I will never use. You can get all your other parts at Radio Shack and make or purchase the encoder method from Sparkfun I think? This is a great starter project.
Any movement of the crank should keep the sound going without interruption with a 2.4 sec delay before the sound shuts off, this is adjustable if needed. At first just tap the C2 capacitor bottom side to ground with a wire to get the idea.
I agree. Old Temeculas proposal is the simplest one so far. However his approach is to use an external mp3 player and provide a mute function to the audio output. This would provide an audio on off function with the handcrank. I believe Lyndon’s approach using an mp3 player integral to the microprocessor controlling the pause function is more viable. The music would then start where it left off when restarting the handcrank. What do you think?
lyndon:
I think you have your Vactrol optoisolator backwards.
Hello Lyndon,
Backward ? Which section. My logic is wrong though, the 2.4 sec delay is how long the sound is Off before it can kick back On again. 555 Pin 3 is always low during cranking as long as C2 gets that negative pulse to discharge C1. This keeps a forward bias on the LED side of the Vactrol. My thinking has slowed with age and I did not breadboard which I would normally do.
Replace the Vactrol with a digital switch or relay can also control the Mute/Pause function on a MP3 player?
The input and output sides are reversed (I assume a Vactrol is an optoisolator?). The phototransistor side should be controlling the MP3 player.
As far as muting/unmuting the volume goes, I agree. However, if the circuit was used to control the Play button of the MP3 player instead of the output, it would be able to start and stop the music: this is exactly how the circuit I mentioned earlier works. It’s also the cheapest solution since the hardware costs less than $5 and you can get an MP3 player for about $10 (or free if you ask around for an old one).
I personally would throw a small computer (Raspberry pi/Beaglebone) at this problem, but that’s because I already have the hardware paid for and available!
lyndon:
The input and output sides are reversed (I assume a Vactrol is an optoisolator?). The phototransistor side should be controlling the MP3 player.
Hi there, the Vactrol is slowly becoming a thing of the past if not already. I drew that little graphic of the Vactrol. The 555 turns on a LED which reduces the resistance of the CdS cell it is pointing at internally. There are modern replacements for this part which in music introduce a slight distortion in the audio wave that does not happen passing through the CdS. In the above graphic I am switching the CdS from Off (~4 megs) to On (200 ohms). Here is a sample using the Vactrol to control the shading of sound as if you were turning the volume up and down. I cannot play a musical tune rather sweep the vocal range in frequency. [[Sample.mp3](http://www.oldtemecula.com/theremin/tw/tube-ss-voice10r.mp3)
Stop laughing if this is a freaky sound, it is played without touching anything. :lol:
