Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Why we connect a capacitor with resistor in parallel ?

Status
Not open for further replies.
F

FAHIM REAZA

Newbie level 3
Joined
Jan 26, 2013
Messages
4
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Dhaka, Bangladesh.
Activity points
1,319
Most of the 4.7V acid battery (which is mostly used in china led lamp) charger circuit we used a cpacitor (105J 400V) and a Resistor (560k) , which is connect with parallely. What is the advantage of it ?
Anyone can help me with describe it with elaborately ?
 

Re: Why we connet a capacitor with resistor in parallel ?

The resistor is used to discharge the capacitor when power is switched off to prevent electric shock as a result of the stored charges in the capacitor.if the resistor is not present,when the power is off,the capacitor retains the charge.any touch of the capacitor terminal will cause electric shock.by placing the resistor across the capacitor the retained charges is discharged through the resistor making it safer.hope it helps
 
Re: Why we connet a capacitor with resistor in parallel ?

What is the working application of those types of capacitor in this types of charger circuit ??

- - - Updated - - -

What is the working application of those types of capacitor in this types of charger circuit ??
 

hi
are you talking about the resistor||capacitor in series with 220VAC and battery (before rectifier) ?
if yes, this is used to step down the high AC voltage.
Google "Transformer less power supply"
 
Thanks a lot.................
But how can I calculate passing voltage & current through this types of capacitors ? That means suppose for 3v , 6v or 9v .......etc , how can I choose a certain valued capacitor ?
 

To calculate the curent you use Ic=V/Xc where Ic is the curent,V is the suply voltage.Xc=1/2*3.14*F*C.your f is mains frequency while your C is the capacitance{105,155,225 etc}.the higher the capacitance the higher the current that can be obtained.the capacitor to be used is dependent on the suply voltage.usualy 400v is selected for 220v-240v mains voltage.for 110v,250v is usually selected.depending on the output voltage and curent needed you can use a 78lxx or a zenar regulator
 

When you connect capacitors in series, any variance in values causes each one to charge at a different rate and to a different voltage. The variance can be quite large for electrolytics. On top of that, once the bank is charged, each capacitor's leakage current also causes a different voltage across each capacitor.
If you charge a series bank up all the way, some caps are always undercharged and some overcharged (not good). To help them share voltage equally, you add balancing resistors. Basically the resistors act as a big voltage divider and counteract the effects of variance in capacitance and leakage current. And if there is no leakage current, the capacitors must eventually become charged according to the voltage divider values.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top