EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: soldar on January 30, 2019, 08:10:23 am
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I have a bunch of computer speakers which I have kept over the years. The type with amplifier included. Some work fine, some one channel does not work correctly. I am sure they would be easy to repair but these things are so cheap it is not worth repairing them. Even the ones which are in perfectly good working order are worthless and I can't give them away because nobody wants them. OTOH I hate throwing things away and I would love to find some use for them.
Maybe something like use them with an oscillator to make some kind of alarm or timer. Something people might have some use for so that I could give them away. It would have to be something simple.
I'd welcome ideas for small projects which would require a small speaker.
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http://www.analogzoo.com/2015/01/building-the-widlar-hassler/ (http://www.analogzoo.com/2015/01/building-the-widlar-hassler/)
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Bat detector?
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A redundant computer speaker has most of the major parts to create a circuit tracer or a pair of them could be cobbled into an intercom.
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You might be able to pick out two matching units in working condition that does not have built-in amplifier, and put them into a Hi-Fi set with your own audio power amplifier module.
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I dropped a Bluetooth receiver into mine and they are the shack sound system. They are an ancient set of two way PC speakers I got 20+ years ago and the sound is great.
Even if you have a set with a blown channel pick the best sounding ones and bluetooth Amplifiers are as cheap as chips on evilbay.
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Skype call dedicated speakers.
My dad 99% uses headphone so my mom stay quiet. Problem when is not at the pc and I skype him he will not get it.
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You can also connect a Raspberry Pi with an external sound card to one of those as a media streaming solution. Tuck the Pi to somewhere less visible for better appearance, and it is also possible to hack the units to allow the Pi to control the power to the speakers.
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You could get a car radio at a flea market and make yourself a stereo system with it. I've seen some of the cheaper android versions pop up at flea markets from time to time (Along with lots of Chinese deathdaptors...)
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Hang them from the ceiling for "surround sound"
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I've always thought about making a whole house audio tracking system, so you have speakers in every single room, and they are connected to a central hi-fi (using all of the neatest legacy/retro gear no doubt!) but get switched on only when you are in the same room. That way you can move from room to room, cleaning, or doing whatever, and have the audio follow with you without the need for headphones. It's the best use I can think of for a metric shit ton of speakers, time, and patience.
It could be done as simple as broken light beam detectors to track anything tall enough to be a human moving from room to room, or as complicated as using NFC trackers to get approximate position relative to tracking stations.
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I used to build and install intercoms but today I don't need any and if I ever do they are cheaply available. I am looking for ideas of things that are not widely and cheaply available. So any normal audio applications are probably not worth doing.
I like the "hassler" idea and I might build one. I do not like loud people. But looking at the circuit it says it oscillates from 12 KHz to 28 KHz! No way I could even hear that! Not to mention these speakers are probably very inefficient at those frequencies. But having an alarm, siren or buzzer go off when people shout is a good idea. I like it.
A continuity tester is also a good idea.
I just thought of making an alarm such that if you move the thing it will sound. You could hang it on a door or put it over something, then, when someone moves the thing, the alarm sounds.
Another thing might be a simple timer if you might need the same time measured often. Hit the button and after x time you hear the buzzer go off.
Maybe also a water alarm or some other type of alarm. They would all have in common just an oscillator driving the speaker and some switch or circuit to enable it. Too bad I do not have any need and I cannot think of anyone who does.
In my old radio days I would sometimes use small speakers as microphones and they would give very good quality.
Keep the ideas coming.
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Perhaps silicon around the openings and use them as channel markers in a nearby river?
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Pick out the nicest pair, refurb them and add a switchable gain OPAMP preamp, with phono jack inputs so you can use them as a general purpose bench audio monitor amp. Also add a mono BNC input (1Meg||25pF) so you can use an ordinary scope probe. Make it as bullet-proof as possible with a series resistor and clamping. Build a rectifying RF probe for signal tracing, to connect to the BNC input or to your scope.
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make a RF / AF signal tracer
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I've been thinking that I would like to hook my terminal applications into some kind of audio frequency output so that when I was compiling software that takes a long time (more than just three or four minutes) I can hear something, so I can tell if it hangs. Even if I cant do something much simpler, (making a less obtrusive sound) it should be possible to do this with 'beep' (I'm on Unix, similar programs likely exist elsewhere) It would be even better if this system to notify me could work all over the house.
There are fairly low overhead programs like mpd which you can use to play music from a computer in one room to speakers in another. Any SBC, for example, any Raspberry Pi has enough power for this.
I try not to throw away nice powered (or unpowered) speakers. They are always useful to have. Its usually pretty easy to find replacements or even repair torn speaker cones. A US company, Parts Express sells all sorts of (hard to find otherwise) speaker drivers and parts (as well as a really excellent pair of very inexpensive small bookshelf speakers, the equal of much more expensive brands.)
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I used an amplified speaker to make a morse code oscillator. Simple oscillator circuit added inside the housing. I added an external volume pot and jacks for headphones and a straight key. Kept it awhile and then sold it.
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"General purpose bench audio monitor amp" is a good idea. I don't often need it but when I do I end up wasting time looking for speakers, connectors, etc. Good idea.
"Morse code oscillator" would be popular some decades ago and I know I built and had one when I took my morse code exam but I am afraid today nobody has any interest in learning Morse code.
This gives me the idea of building a simulated morse code receiver which would just beep randomly or even transmit some predetermined string. It might make a cool gadget. Press a button and it rattles out Morse code for a while. It could output dots and dashes randomly or a predetermined string but this would require some more complexity. I need to think about this.
Maybe combine the "Hassler" with the Morse and have it play some Morse when voices get to loud. Not bad idea.