Filter Capacitor: Eliminate Residual Ripple at 1.4V

[Ravaner]

Hello. I have a load powered at 1.4 V through rectifier bridge and capacitor 4700 µF. A residual ripple appears. As I need to eliminate this ripple I project to install a 1 F "saving capacitor " ( sorry I don't know the exact name in english ) as used to protect data in computers. Is there anything wrong in this project ?

 

[the_emi_guy]

How much ripple appears?
How much ripple can you tolerate?
What is the frequency of the ripple?

 

[vk6kro]

Hello. I have a load powered at 1.4 V through rectifier bridge and capacitor 4700 µF. A residual ripple appears. As I need to eliminate this ripple I project to install a 1 F "saving capacitor " ( sorry I don't know the exact name in english ) as used to protect data in computers. Is there anything wrong in this project ?

Using very large capacitors will cause a problem with charging current. When you first apply power, a very large current will flow from the power source to the capacitor and this may well destroy the diodes and/or the transformer in the power source.

It would be better to use a voltage regulator. You could consider the LM317K which could deliver voltages as low as 1.2 volts.
Or if you have Ebay access, you could look for a step-down regulator (sometimes called a "buck" regulator) which would be more efficient.

Just as an example, you can get these:
http://www.ebay.com.au/itm/KIS-3R33S-DC-DC-Step-Down-Power-Supply-Module-3A-LED-GPS-MP3-MP4-/130716540737?pt=AU_B_I_Electrical_Test_Equipment&hash=item1e6f501f41

This has current limiting, voltage output from 0.95V to 20 volts, current up to 3 amps, and costs less than US$5 delivered.

 

[Ravaner]

Many thanks for your replies

 

[alphysicist]

Hello,

Thank you for sharing your project with me. It seems like you are trying to eliminate the residual ripple in your load by adding a 1 F "saving capacitor." This is a common solution to reduce ripple in electronic circuits, as capacitors are able to store and release energy quickly. However, there are a few things to consider before implementing this solution.

Firstly, it is important to ensure that the "saving capacitor" is rated for the appropriate voltage and has a low enough ESR (equivalent series resistance) to effectively filter out the ripple. If the capacitor is not rated for the voltage in your circuit, it could potentially fail and cause further issues. Additionally, if the ESR is too high, the capacitor may not be able to effectively filter out the ripple.

Secondly, it is important to consider the overall capacitance in your circuit. Adding a 1 F capacitor in parallel with your 4700 µF capacitor will increase the total capacitance of your circuit. This may affect the charging and discharging times of your circuit, potentially causing unintended consequences.

Lastly, it is important to consider the cost and space constraints of adding an additional capacitor to your circuit. Depending on the size and cost of the "saving capacitor," it may not be a practical or cost-effective solution.

In summary, adding a "saving capacitor" in parallel with your existing capacitor may be a viable solution to reduce the residual ripple in your circuit. However, it is important to carefully consider the specifications, overall capacitance, and practicality of this solution before implementing it. I hope this helps and wish you success in your project.

Best,