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Fish Sinatra
Alec Towsley
Input
This schematic is the LM380N which handles the audio amplification to take the input of the audio jack and convert it into a more usable format by the speaker and the rest of the circuit. It basically functions as the first amplifier in the circuit to make the input be a real signal that we can manipulate.
As you can see we swing between positive and negative voltage to convey sound, in the case of music our peaks are typically vocals as you need to hear the signer over the music in the background
Conversion
The 555 timer is the brains of the operation. It handles the input signal and converts it into a square wave that triggers only when the input voltage hits a certain point. This point is typically 1/3V input for the lower trigger and 2/3V input for the upper one. The two 10k potentiometer allow you to adjust that level to something that actually works for the
input signal.
This is the results of the schmitt trigger working as expected. At the bottom you can see a small amount of noise caused by the input spilling a little outside of the expected range.
However you may also notice that the output is far too low to trigger any voltage based switching. For this reason our next circuit will be an Op Amp
Something else to note is that the current has dropped at this point to be too low to trigger a transistor, or a PST relay. This limits our future options down to a Reed Relay
Additionally the lower trigger is above zero at this point, so we will need to address that with a voltage clamp if possible.
amplification
The LM358 is a single pole Op Amp circuit. This allows us to only feed it the desired upper limit and leave the lower limit as ground or 0V. This reduces the complexity of the circuit greatly and only requires two resistors to make it into a non-inverting amplifier. In our case a gain of 5 is plenty to get us close to 12V.
This is our output signal after amplifying it properly. As you can see the lower trigger voltage is far too high, and will tie any switching high regardless. For this reason we need to pull the entire signal down around 2 Volts. To accomplish this, our next step is to add a voltage clamp with a bias of 0V.
Correction
The voltage clamp is built to hold the voltage positive and bias it to whatever sits below the voltage is below the resistor and the diode. In our case we can leave that as ground since we just need to pull it to ground.
As you can see from our output, we finally stay close enough to 0V to prevent false positives, while keeping our output high enough to be seen by the Reed Relay that will handle the physical switching.
output
The Reed Relay is a basic relay that toggles exclusively on voltage and not amperage. This means that we can output our 9V, and use it to supply a motor with the required voltage.
With that our circuit is completed. Each component feeds into the next and creates the effect of converting an audio signal into a driven motor at user specified values.
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