Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
Audio files: 14
Posted: Thu Dec 01, 2011 5:17 pm Post subject:
Weekend of Weirdness
I have some chips and some transistors and some ideas and a secret laboratory and I am devoting a 3 day weekend entirely to creating weird sound machines made from as few chips as possible.
What will I make!? What will it sound like!? Only Poseidon knows! (the king of the sea and therefore sea moss too)
I will share the results of my work here.
Crazyness.png
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This is just a sample of the crazyness which could be in store!
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Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
Audio files: 14
Posted: Fri Dec 02, 2011 3:15 pm Post subject:
It's pretty much done now. I just need to fine tune things a bit
Circuit description: a few low frequency oscillators made with a 7414 go into an R2RD2 resistor ladder/droid and then act as a control voltage for a VCO, then the waveform is recombobulated by my my patented pulse width modulation circuit
Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
Audio files: 14
Posted: Sat Dec 03, 2011 5:43 am Post subject:
It's probably the standard thing everyone uses but I shall explain anyway;
Simply use an op amp as a comparator.
Feed one of the inputs with an audio frequency waveform with sloping sides like a triangle sawtooth or even a sine would work. Then feed the other with a voltage, if it is above or below the peak to peak voltage of the audio waveform the comparator will output a pulse wave of 0% or 100% so it is a good idea to keep the modulation voltage between the peak to peak voltage of the audio wave.
I'll attach a graph, graphs explain everything better.
The blue triangle wave is the audio frequency input, the green rising line is the control voltage, the red wave is the output.
(the corners of the pulse are slightly rounded because I used an LM324 op amp, it would be squarer if you put it through a schmitt trigger afterwards or used a better op amp)
You can see that when the control voltage goes above and below the peak and trough of the wave, the duty cycle is 100% or 0%, the output of the comparator flips when the audio wave crosses the control voltage.
PWM graph.png
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Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
Audio files: 14
Posted: Sat Dec 03, 2011 10:07 am Post subject:
Saturday: 1700
So... Much ... Tweaking.
Two important lessons learnt from this:
Don't use TTL.
Buy the right potentiometers by double checking all your readings first.
I don't have the camera right now or I'd record a video of my latest developments, the device now makes even more bleeps and the LFO modulation of the pulse width is working great
Still more work to do though!
Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
Audio files: 14
Posted: Sun Dec 04, 2011 11:30 am Post subject:
After hours of fine tuning and fiddling it is finally finished! It's only on breadboard for the moment but I shall solder it up and put it in a box soon
Circuit diagram coming soon, watch this space!
Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
Audio files: 14
Posted: Sun Dec 04, 2011 2:31 pm Post subject:
The point of this project was to finish it quickly (over one weekend) and use as few IC's as possible and still get alot of bleepy weird noises.
Now we can get down to the technical details
For this device I only used an LM324 op amp, and a 7414 inverting schmitt trigger (note: never use a 7414 schmitt trigger, it's TTL and therefore very difficult to make work properly, use a 40106 instead)
The diagram shows a 40106 but these values are for a 7414 schmitt trigger.
Description of operation:
Four of the schmitts are used to make oscillators which go into four rungs of an R2R ladder, which gives the nice crazy control voltage for the VCO. This voltage is attenuated and re-combobulated by the op amps following it (lots of tweaking was required and resistors needed to be added to the potentiometers to eliminate the dead zones at the end of the turn). Ultimately they give level control and initial pitch control.
The last schmitt trigger was used to make an LFO, attenuated in the same manner and used as a pulse width modulation control.
I don't mean to blow my own horn but I think I did pretty well to get so much out of just two chips.
R2RD2 schematic.png
Description:
Error correction: R12 should connect to C5, not the output of U5. The cap gives a sort of triangular wave and the output will give a square wave.
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Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
Posted: Mon Dec 05, 2011 4:15 pm Post subject:
inlifeindeath wrote:
inventor! where you been?
i was posting this summer but got little response cause other people have outdoorsy things do do in the summertime and em slows down on the forum in summer, then i stopped for a while because i moved to texas where i had a wild and insane adventure which landed me in a rehab center where i am now. Things are just settling in to the point that I can get back on em now.
Les _________________ "Let's make noise for peace." - Kijjaz
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
Posted: Tue Dec 06, 2011 10:34 am Post subject:
Actually it is Texas that is saving me, not causing the problems. I had a poor opinion of Texas before as well, imagining the place to be full of gun toting republican waco fanatics. Well nothing could be further from the truth. People here are friendly and go out of their way to help you, the medical facilities are excellent, and even the police are nice. Compared to the east coast or west coast, Texas is the best kept secret in the USA. I'm very happy here. Who would have thought that? _________________ "Let's make noise for peace." - Kijjaz
Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC
Posted: Tue Dec 06, 2011 10:38 am Post subject:
I'm glad to hear that - I've got some friends that absolutely love the place. I've had some bad samples I guess, most notably driving through west Texas with the family when we moved cross country. Nothing but Rednecks and Dairy Queens as far as the eye could see (and you can see a LONG way in west Texas).
Anyway, I'm glad to hear you're doing well. Stay strong and feel better...
I'd have to say Florida is a much worse place than Texas. Also, I completely agree about West Texas. Pretty miserable.
Glad to hear you're on a better track Les! Best wishes! _________________ http://www.youtube.com/user/borisandfef
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