Ghani Lawal- Constructed and tested Circuit on a breadboard
- https://www.eeweb.com/dual-supply-from-single-battery-source/
- Input voltage to MC79L00 -5V regulator needs to be -7V or below, however when the circuit is loaded with 1 kohm, the voltage goes up to just under -7V, meaning that it us supplying 7mA, i.e circuit can't meet voltage and current needs
- https://www.electronics-tutorials.ws/waveforms/555-circuits-part-2.html: The Negative Voltage 2X
- When I physically tested the circuit under no load the voltage wasn't actually double, it's just a negative of the input voltage,
- ^confirmed that circuit simply creates negative of the input voltage, doesn't double
- https://www.electronics-tutorials.ws/waveforms/555-circuits-part-2.html: Basic Multivibrator Circuit
- Used the Same Ra, Rb and C values that were used on this webpage
- At no load, Vo = -13.37; 1kohm, Vo = -11.14; 470ohm, Vo = -8.18, more than meets voltage and current needs
- ****It seems that and Ra, Rb pair that gives low duty cycles allows for a more stable output voltage, since D = (Ra + Rb)/(Ra+2Rb), limit of Duty cycle is 50%
- Used caps of 200uF in the multiplier circuit that can handle 10V, actual values were [120u:160u], switched out with caps of same value that can handle 50V, no difference in output voltage stability when loaded, though it was found that using larger caps reduced "triangle noise"
- https://www.eeweb.com/dual-supply-from-single-battery-source/
- Will use Ra = 1k, Rb = 10k, C = 50n
- Simulate 555 timer multiplier circuit in LTSpice
- LTSpice has a 555 timer element called NE555, "NE" must be typed or won't get to the part
- At no load, Vo = -16.25; 1kohm, Vo = -13.70; 470ohm, Vo = -12.20
- Was found that for the first cap in the multiplier circuit, there are spikes of 1.5mA that last for less than 1u
- max current that 555 timer can source or sink is 200mA
- on my multimeter, amplitude of the ac current is 41.64mA, possible that it can't register the spikes
- 555 timer being capped to 200mA may be why Vo in physical implementation is lower in absolute value than the simulation
- Theory doesn't completely hold up when circuit isn't loaded, but this is good enough for now
555 Timer Negative Voltage Muliplier
A project log for Music Spectrum and dB Visualizer
Receive input from a 3.5mm jack, divides the music into 7 frequency bands, shows the loudness of each frequency band in DB using LEDS.
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