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projects:spectrumanaliser:step1_hardware [2012/05/06 10:11] elger |
projects:spectrumanaliser:step1_hardware [2016/11/16 13:06] |
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| - | **UNDER CONSTRUCTION** | ||
| - | ====== Spectrumanaliser Hardware ====== | ||
| - | |||
| - | There are four hardware components in my spectrumanaliser project; | ||
| - | * Power-supply | ||
| - | * Opamp | ||
| - | * Arduino (clone) | ||
| - | * Display | ||
| - | |||
| - | Here is a short description of why they are needed and how they are connected. | ||
| - | {{:projects:spectrumanaliser:spectrumanaliser_overview.png}} | ||
| - | |||
| - | ===== Power-supply ===== | ||
| - | |||
| - | Usually I would not mention this separately but there is one important thing to know about powering this project. | ||
| - | {{ :projects:spectrumanaliser:spectrumanaliser_powersupply.jpg?200|}} | ||
| - | The Opamp (audio amplifier) is very sensitive. If there is a lot of noise on the power-supply then the opamp. So the best thing to prevent interference from the display on the audio signal is to have one power source for the Arduino and opamp, and another one for only the display. | ||
| - | The Ground (0 Volt line) of both supplies must be connected (of course). | ||
| - | |||
| - | I simply made two 7805 circuits and joined the GND together. | ||
| - | |||
| - | ===== Opamp ===== | ||
| - | {{:projects:spectrumanaliser:spectrumanaliser_opamp.jpg?200 |}} | ||
| - | {{ :projects:spectrumanaliser:lm386_opamp_schematic.png?200|}} | ||
| - | The opamp is based on a LM386. This is a very standard opamp that (also) works on 5 Volt. There is one thing to consider, the ADC (Analog to Digital Converter) on the Arduino can read 0V to 5V, but no negative values. So the output on pin1 of JP4 (see schematic) is 2.5V insilence, and sound can produce up to 0V to 5V. And this is exactly what is usefull for the Arduino. On regular adio projects you would like the AC (-2.5V to 2.5V) signal; this comes out of pin2 of JP4 (see schematic). | ||
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| - | The input for this opamp can be a ecectret condensor microphone, but if you adjust the pot, you can also use a line-in signal from a music-player. | ||
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| - | ===== Arduino (clone) ===== | ||
| - | {{ :projects:spectrumanaliser:spectrumanaliser_arduino_uno_portb.jpg?200|}} | ||
| - | This should speak for its self, I used a Atmega328P based Arduino (a.k.a. Arduino UNO). And the clone I have works just as well. Actually, the clone board has the "portb" marked much clearer so finding the right pins was much easier. | ||
| - | {{ :projects:spectrumanaliser:spectrumanaliser_arduino_clone_portb.jpg?200|}} | ||