Discussion in "Electronics" started by    ankitbajaj01    Apr 16, 2015.
Sun May 03 2015, 04:34 PM
#11
Hello ExperimenterUK...

Attaching the existing power supply circuit here with. Need your inputs in this.
I have put two 0.1uF Cap before 7805 (at 14V Side) and one One 0.1uF at 5V side.
How the value of this capacitor helps? Does smaller value is good? If yes, How small value we can go for?
Also, I have connected one 0.1uF at VCC pin of the AT89S52.
How does these capacitors work? Are they also rated with Voltage?

Regards...

Sun May 03 2015, 06:12 PM
#12


How the value of this capacitor helps? Does smaller value is good? If yes, How small value we can go for?
Also, I have connected one 0.1uF at VCC pin of the AT89S52.
How does these capacitors work? Are they also rated with Voltage?

ankitbajaj01


Because of their physical design , electrolytics are not good at dealing with high frequency pulses.
Ceramics can handle these pulses so are used as well as electrolytics.
0.1 uF is a good size, less is not better.
Ceramics are usually rated at 50 volts, I'm sure yours will be okay.

What sort of relay are you using ?


[ Edited Sun May 03 2015, 06:15 PM ]
Mon May 04 2015, 04:58 PM
#13
Hello ExperimenterUK...
@Ceramic Capacitor
What if we took ceramic capacitor of higher values?
I have put tow 0.1uF, that would be 02uF. Will it be putting good effect?

@Relay
I am using Mechanical Relay of Leone Company. (SC5-Ag model of 7A) or (L90H model of 20-30A or 40A).
InRush Current for 1 hp motor is approx. 12-15A and 2hp it would be Approx. 25A.
What are the good brands for relay?
Recently I have got to know about relay contact protection. I am also going to implement that soon. If you can throw light on it, it would be helpful.

Regards...
Mon May 04 2015, 05:02 PM
#14
@Electrolytic Capacitor...
Putting 220uF cap at 14V side and 100uF cap at 5V will work under low voltage condition to provide sufficient Volts, right?
Correct me if I am wrong...

Regards...
Tue May 05 2015, 05:58 PM
#15


What if we took ceramic capacitor of higher values?
I have put tow 0.1uF, that would be 02uF. Will it be putting good effect?

ankitbajaj01


Yes, two will be better than one.


I am using Mechanical Relay of Leone Company. (SC5-Ag model of 7A) or (L90H model of 20-30A or 40A).
InRush Current for 1 hp motor is approx. 12-15A and 2hp it would be Approx. 25A.
What are the good brands for relay?

ankitbajaj01


I don't think there is much difference in brands , just use one with a high enough contact rating.
7 amps is too small.


Recently I have got to know about relay contact protection. I am also going to implement that soon. If you can throw light on it, it would be helpful.

ankitbajaj01


You can fit a filter to limit sparking, but I don't think it would be worth doing here.
Just use a big relay.


Putting 220uF cap at 14V side and 100uF cap at 5V will work under low voltage condition to provide sufficient Volts, right?
Correct me if I am wrong...

ankitbajaj01


I assume you meant 2200uF ?
Yes those should be enough, but if you get switching problems try bigger values.
Also try a mains filter on the supply to the transformer.

Wed May 06 2015, 09:08 AM
#16
Hello ExperimenterUK,

@ Ceramic Cap...
If bigger is better then how to get to know, how big is enough (theoretically/practically - how to check it? How does this cap actually work? So that we can place exactly what is required)

@Relay...
For the 1 hp motor whose steady state current is 4A and inrush current is 15A, in one firm they are using 7A realy from long back. I was not able to understand that how 7A relay is working for the inrush current of 15A. I was in dilemma that is inrush current is not supposed to consider in selecting Relay and only steady state current is required to be selected?

@ Relay Contact Protection...
Can you elaborate on how to design or select such filter circuit? any notes or if you can directly guide me in brief.

@2200uF cap selection...
can we theoretically/or by measuring current or Voltage, predict which cap is required?

@ mains Filter...
I am not much aware of mains filter. I would appreciate if you put on some light on that as well.

Regards....
Always happy to learn from you.
Tue May 19 2015, 07:00 AM
#17
Hello ExperimenterUK...
Please guide me on above points...
Regards...
Sat May 23 2015, 09:44 PM
#18
For all your questions there is a proper, very technical way to do it.
I doubt many people other than professional circuit designers follow those rules.
I certainly don't .. but they are on the Web if you want to look.


@ Ceramic Cap...
If bigger is better then how to get to know, how big is enough (theoretically/practically - how to check it? How does this cap actually work? So that we can place exactly what is required)

ankitbajaj01



Ceramic Caps are often not needed, but one 0.1uF cap as close as possible to each chip should be enough.
Using more or bigger values can't do any harm.


@Relay...
For the 1 hp motor whose steady state current is 4A and in rush current is 15A,
in one firm they are using 7A realy from long back.
I was not able to understand that how 7A relay is working for the inrush current of 15A.
I was in dilemma that is inrush current is not supposed to consider in selecting Relay and
only steady state current is required to be selected?

ankitbajaj01



As far as I know a relay should be rated to handle the maximum current it will carry
so at least 15Amps.
A 7amp relay will work, but wear out faster.

I would go for at least a 16 amp rating.




@ Relay Contact Protection...
Can you elaborate on how to design or select such filter circuit?
any notes or if you can directly guide me in brief.

ankitbajaj01


In a word .. no
Sorry such designs are too specialized for me, you will have to look for
application notes on the net.

For 1 hp motor I'd just use a big relay, a filter is not going to make much
difference.


@2200uF cap selection...
can we theoretically/or by measuring current or Voltage, predict which cap is required?

ankitbajaj01


There are many website that cover simple power supply design.
Very often they end up playing safe and doubling or trebling the calculated size.


@ mains Filter...
I am not much aware of mains filter. I would appreciate if you put on some light on that as well.

ankitbajaj01


A mains Filter is usually some combination of a capacitor a choke and a resistor to remove
noise spikes from the mains supply.
The most practical way is to buy a purpose made filter (or strip one from old equipment).





[ Edited Sat May 23 2015, 09:47 PM ]
Wed Jun 03 2015, 06:08 PM
#19
Hello ExperimenterUK...

I am trying to learn more about mains filter.

If you can guide me, I want to know the difference between full size and half size crystals!!!!

Regards....
Fri Jun 05 2015, 01:21 AM
#20


I am trying to learn more about mains filter.

ankitbajaj01


I can't really add much to what i said before.
There should be useful information on line.


If you can guide me, I want to know the difference between full size and half size crystals!!!!

ankitbajaj01


I'm not sure what you mean, can you give links to pages talking about
full size and half size crystals ?.

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