I have a full wave bridge rectifier with two capacitors @470ufand 3 resistors in series @ 100, 100 and 1 ohm, can you explain the effect the size of capacitor has on the ripple? and also the effect of the size of the load resistance on the ripple? Thanks
2007-02-23 03:31:51 · 4 answers · asked by socemental 1 in Science & Mathematics ➔ Engineering
The larger the filter capacitor, the less the ripple (voltage), because larger capacitance means more energy stored, which means less voltage droop (ripple).
The lower the load resistance, the higher the current draw (from the capacitors), so the droop rate is faster, hence the ripple voltage goes up.
(I wish I had graphics to show you).
https://www.national.com/an/AN/AN-556.pdf
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2007-02-23 03:38:04 · answer #1 · answered by tlbs101 7 · 1⤊ 0⤋
"Ripple" in a power supply is defined as the AC component that remains after rectification. The 'ripple" voltage will be affected by not just the size of the capacitor, but also by it's reactance to the frequency of the AC voltage being fed to the rectifiers. In a full wave rectifier, that frequency will be 120Hz, for a 60Hz line frequency. If the load is trying to draw more current than the supply can provide, then the "ripple' voltage will increase. This due to the RC time constant between the load resistance and the capacitor. The capacitor simply does not have sufficient charge time to reduce that AC component. Take that capacitor up to 4700 uF, or higher and see what happens to your ripple voltage, if you have access to an oscilloscope. A general rule of thumb is that for every 1 amp of current draw you need 1000 uF of filter capacitor capacity.
What a regulator would do for that ripple is effectively block it, provided the regulator has at least 3 volts more being supplied to it than the load voltage it is supplying. In effect, it is much like the Limiter stage in an FM radio to noise riding on the demodulated radio signal, it just clips it off.
2007-02-23 22:21:50 · answer #2 · answered by Anonymous · 0⤊ 0⤋
the full wave gives you a lower ripple.
It depends on three things,voltage,current and regulation.
If the load is high you need a larger capacitor.
In IC circuits you will also need a voltage regulator.
2007-02-23 11:53:27 · answer #3 · answered by Billy Butthead 7 · 1⤊ 0⤋
What do you mean by full wave rectifier? Do you mean some sort of sound wave, or like the wave generators at those swimming pools?
2007-02-23 11:34:27 · answer #4 · answered by Anonymous · 0⤊ 3⤋