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IFD:Analog Circuits and Interfaces/introduction to electronics (view source)
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[http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+12.050203812241895+54+5+43%0Ag+-240+96+-240+112+0%0Ax+-134+-188+297+-185+4+18+Self-Oscillating%5CsComparator%5Cs(Square%5CsWave%5CsGenerator)%0Aa+-240+0+-128+0+8+15+-15+1000000+6.090293760309295+7.500070481327725+100000%0Aw+-128+0+-96+0+0%0Ag+-304+-16+-304+0+0%0A207+-96+0+-48+0+4+output%0Ac+-304+-16+-240+-16+0+1.0000000000000001e-7+-6.090293760309295%0Ar+-240+48+-240+96+0+100000%0Ar+-240+48+-128+48+0+100000%0Aw+-240+16+-240+48+2%0Aw+-128+0+-128+48+0%0Ar+-240+-64+-128+-64+0+100000%0Aw+-128+-64+-128+0+0%0Aw+-240+-64+-240+-16+2%0Ao+9+64+0+4098+10+0.00009765625+0+2+9+3%0Ao+13+64+0+4098+10+0.00078125+1+2+13+3%0A Square Wave Generator] | [http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+12.050203812241895+54+5+43%0Ag+-240+96+-240+112+0%0Ax+-134+-188+297+-185+4+18+Self-Oscillating%5CsComparator%5Cs(Square%5CsWave%5CsGenerator)%0Aa+-240+0+-128+0+8+15+-15+1000000+6.090293760309295+7.500070481327725+100000%0Aw+-128+0+-96+0+0%0Ag+-304+-16+-304+0+0%0A207+-96+0+-48+0+4+output%0Ac+-304+-16+-240+-16+0+1.0000000000000001e-7+-6.090293760309295%0Ar+-240+48+-240+96+0+100000%0Ar+-240+48+-128+48+0+100000%0Aw+-240+16+-240+48+2%0Aw+-128+0+-128+48+0%0Ar+-240+-64+-128+-64+0+100000%0Aw+-128+-64+-128+0+0%0Aw+-240+-64+-240+-16+2%0Ao+9+64+0+4098+10+0.00009765625+0+2+9+3%0Ao+13+64+0+4098+10+0.00078125+1+2+13+3%0A Square Wave Generator] | ||
[This is the breadboard version of the square wave oscillator. The output frequency should be around 50-100Hz. You can connect this to a small speaker or headphone directly. To connect it to a Hifi amplifier input, you need to convert the output voltage from around +-4V to +-1V by using a voltage divider. | [[file: square_wave_oscillator.png]] This is the breadboard version of the square wave oscillator. The output frequency should be around 50-100Hz. You can connect this to a small speaker or headphone directly. To connect it to a Hifi amplifier input, you need to convert the output voltage from around +-4V to +-1V by using a voltage divider. | ||
* To shape the spectrum of our oscillators we will use a lowpass filter. The simplest form of a lowpass filter is the passive lowpass filter. You can view this lowpass filter as an elaborated voltage divider: the capacitor has a frequency dependent resistance (which we call an impedance). This impedance is very high for static voltages (DC) and low frequencies. The impedance goes down the higher the frequency is at its input. The higher the frequency, the lower the impedance at the capacitor and the lower will be the voltage at the capacitor. This will effectively filter out high frequencies and leave lower frequencies in the signal. | * To shape the spectrum of our oscillators we will use a lowpass filter. The simplest form of a lowpass filter is the passive lowpass filter. You can view this lowpass filter as an elaborated voltage divider: the capacitor has a frequency dependent resistance (which we call an impedance). This impedance is very high for static voltages (DC) and low frequencies. The impedance goes down the higher the frequency is at its input. The higher the frequency, the lower the impedance at the capacitor and the lower will be the voltage at the capacitor. This will effectively filter out high frequencies and leave lower frequencies in the signal. | ||