3 caps RC

Status
Not open for further replies.

shortbus

Joined Sep 30, 2009
10,045
Another question that only the designer of the circuit would know. Some day you will learn that a designer/engineer does what they do because that is the way they do it. There is no "name" for it.
 

profbuxton

Joined Feb 21, 2014
421
Use three caps: Reasons
(1) gives the required capacitance for the design
(2) Cheapest available components available in quantity at the time
(3) Thats what was in the makers store at the time.
 

Thread Starter

DexterMccoy

Joined Feb 19, 2014
429
Does adding 3 caps, Triple the storage , so it stores the voltage better VS having One cap do it?

having 3 caps, with 3 different cap values, is 3 different phase angles
 

Wendy

Joined Mar 24, 2008
23,421
Again, really basic questions, things taught in 1st year 3rd week tech school.

Caps in parallel are additive, and their highest voltage is what ever the weakest link is. In other words, the cap with the lowest voltage rating.
 

BillB3857

Joined Feb 28, 2009
2,570
Does adding 3 caps, Triple the storage , so it stores the voltage better VS having One cap do it?

having 3 caps, with 3 different cap values, is 3 different phase angles

No, the three shown would have the same effect as a single with the value of the sum of the three.
 

Wendy

Joined Mar 24, 2008
23,421
Mostly. There is also an issue of frequency response of capacitors. If this were a power supply filter they may use the large electrolytic caps to take care of 60 cycle hum and smaller caps to take care of faster transients.
 

Thread Starter

DexterMccoy

Joined Feb 19, 2014
429
So the power supplies load?, can have fast transients from the load current

So you're saying that the power supplies load can "reflect" fast transients into the power rails?
 

Wendy

Joined Mar 24, 2008
23,421
Digital logic, which you have asked many questions about, create fast transients. So do light switches, or relays or any number of other things. Ultimately everything ends up in the power supply rails.
 

Thread Starter

DexterMccoy

Joined Feb 19, 2014
429
Digital logic, which you have asked many questions about, create fast transients. So do light switches, or relays or any number of other things. Ultimately everything ends up in the power supply rails.
Well they use decoupling caps to filter out the fast transients

These transients are overshoot voltages and undershoot voltage
 

Wendy

Joined Mar 24, 2008
23,421
You persist in ignoring the obvious. Bypass caps are in parallel with the power supply caps. They are part of the total capacitance, just like the example you gave when asking the question.
 

Thread Starter

DexterMccoy

Joined Feb 19, 2014
429
Digital logic,, create fast transients. So do light switches, or relays
The Transients are caused by the voltage and current potential difference being shunted or shorted out to ground without any draining off or transient protection

Relays have a parallel diode
Switches have a parallel capacitor

This helps CLAMP the voltage and current on the transient
 

Wendy

Joined Mar 24, 2008
23,421
Not always. Electronics is rarely about absolutes. Clamping diode have switching speeds, for example. And the act of contacts causing a current draw can cause transients. A 100W light bulb draws almost an amp, which going to show up on the mains.

You said it yourself, it helps. It is not perfect.

Batteries also have internal resistances which help contribute.
 

ian field

Joined Oct 27, 2012
6,536
Mostly. There is also an issue of frequency response of capacitors. If this were a power supply filter they may use the large electrolytic caps to take care of 60 cycle hum and smaller caps to take care of faster transients.
Electrolytics in parallel also give a lower net ESR than a single cap - but that's hardly likely to be the issue with a 100R resistor in series with the parallel combination.
 
Status
Not open for further replies.
Top