Figures, right? Turns out, that I completely overlooked the fact that microphones are inherently true AC output devices. I attempted to do this, actually but I believe the op amps I have are broken/fried due to a previous project of mine going south. A way to combat this would be to introduce another amplifier between the microphone and the PT2399. Microphones are inherently small signal sources. The more delay, the more pronounced the distortion is in the output.Īnother potential reason for this is the fact that we're using a microphone directly to the PT2399. It claims to boast a THD of under 0.5%, however this distortion relies heavily on the amount of delay you ask of the IC. The PT2399 is "an echo audio processor IC utilizing CMOS technology which is equipped with ADC and DAC, high sampling frequency, and an internal memory of 44k." This can be easily attributed to any number of different things. This circuit IS the first iteration and as such it does have a few small problems which can be easily fixed. Jared after his eardrums were punctured by a sound related accident. And for the semiconductory bits, pulling up the datasheets for each part can help identify the orientation for them so you don't accidentally put them in backwards. You can also try labeling each part by number, along with the previous technique to really make sure you put it together correctly. It can help, if you're having problems putting it together to print out the circuit diagram and scribble over components you've already soldered on. Jared I need help putting this together! Assist me! A small flat piece of wood just hotglued to it would work too, plus it looks a lot nicer than just a floppy circuit hanging out in the wind. The PT2399 is a CMOS IC, and is very sensitive to static electricity, along with the fact that your fingers will easily introduce noise into the circuit. I would also deeply recommend you mount this circuit onto something or put it in a project box. The potentiometer adjusts how sensitive the microphone pickup is. The second schematic version is for improved sound clarity. There's very little heat dissipated by this circuit. A great program, and 1000 billion times easier to use than paint. I put this schematic together using ExpressSCH. The PT2399 isn't expensive, either, about $1 each! You can get all of these things from eBay, mouser, wherever you source your electronics components. Headset (this is both your output and input, since it works only with a headset on)ġx LM386 (amplifies the delayed audio coming from the PT2399)ġx 7805 regulator (everything on this board will use +5 volts)ġx 9 volt battery clip (this is powered off of a 9 volt battery)Ģx 3.5 mm audio jacks (or you can solder your microphone/speaker directly on, your choice)Ģx 220 uF electrolytic capacitor (non critical value, anything above 100 uF should work)ġx KA358 or equivalent (if using equivalent make sure you're using a single supply capable op amp!!!) I always use protoboard because it's more permanent) Wire (pretty sure this is a given, any thin gauge wire should work) And, if you go with the improved version, a KA358. Only three "active" components, the 5 volt regulator, the PT2399, which controls the delay, and the LM386 which amplifies the audio from the PT2399. It's still amusing to see your friends think " oh, this'll be easy!" and then proceed to have the speech capability of a 2-year-old. However it's not foolproof if you concentrate hard enough, and speak slowly you can overcome the effects of the jammer. It's a pretty funny thing to play with and show people the effects of. I'm thinking this may be due to the way your brain processes your words since there's an inherent "delay" that your mind creates, it somehow interferes with your speech processing center. You have a tendency to start stumbling over your words, and you more or less, just lose your train of thought. But, what happens when this delayed speech hits your ears? This echo is typically within the range of 30 ms - 300 ms, and it varies a bit. This thing is the heart of this circuit, and is actually pretty impressive considering the pricing. Then I found out about a very, very neat little IC, the PT2399. I had planned on making this many months ago, as I previously stated but I was going to try and go discrete, aka, use a micro-controller and attempt to program some sort of delay code. Basically, the intercom would introduce an ever so slight delay to the output of the speaker, so you would end up hearing an echo. I had come up with this idea a while ago, after hearing about the details behind some basic "speech jamming" anomalies that occur when people use intercom systems. This instructable was a LONG time coming.
0 Comments
Leave a Reply. |