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 Post subject: Calculating Capacitor Size
Unread postPosted: Thu Mar 09, 2017 7:58 pm 
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Joined: Thu Mar 09, 2017 7:31 pm
Posts: 5
I have a 12v 4A camera system, just like this: Thin Film Capacitors http://www.kynix.com/Detail/18200/06035J0R5PBTTR.html and I want it to switch from AC adapter to 12v Battery in a power failure.
I am planning to use a relay held on by AC power to switch the load to battery when AC goes away.
I want to use a capacitor to keep power flowing while relay flops over.

Image

How do I figure out the Capacitor size?

I thought I would try keep enough capacity for 1/2 second of 12v power at 4A. (relay should switch much faster than 1/2 second).

I have been puzzled about the topic for couples of months. Today, I come to this forum to turn to you to discuss the calculating capacitor size.

What is your idea ? Do you agree with my ideas ? Any of your ideas would be highly appreciated.

Thanks for any pointers on this.


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 Post subject: Re: Calculating Capacitor Size
Unread postPosted: Thu Mar 09, 2017 10:38 pm 
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Joined: Sun May 19, 2013 10:53 am
Posts: 512
To calculate the capacitor size, we need to know how much current (milliAmps) your camera is drawing during operation and for how long (milliseconds) the capacitor has to substain the camera.

In any case is not a reliable system! A better way to solve you problem is to use two diodes (2x1N4007) and connect one in series to the ac adapter and the second in series to the battery and both, on the positive wire, will be connected to the camera. In this way you will have a no-break system. In case of power failure the camera instantaneously will draw current from the battery pack. Battery pack should supply few millivolt less than the ac adapter, in this way it will be silent ( no current will be taken from the battery while the ac power is on) for this you will need an adjustable regulator (LM317)

You are a lucky guy, since this forum should discuss only basic for android matter and not hardware subject ! I strongly hope not to be banned for this answer! :o :D

Cheers

Alberto

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 Post subject: Re: Calculating Capacitor Size
Unread postPosted: Thu Mar 09, 2017 10:47 pm 
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Joined: Thu Mar 09, 2017 7:31 pm
Posts: 5
thanks for your understanding. Do you think it is an interesting topic ? You can write to the moderator that the topic should not be banned. thanks in advance.


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 Post subject: Re: Calculating Capacitor Size
Unread postPosted: Fri Mar 10, 2017 1:08 am 
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Joined: Tue Jan 03, 2012 9:31 am
Posts: 5518
Location: Paris, France
There is nothing wrong in your answer Alberto ;)

But I'm sorry page123 your post is highly suspicious: this forum is dedicated to RFO BASIC! for Android, and your first ever post is a question about electronics, with an hyperlink to a commercial website in the very first sentence... Please don't do that again, if you wish to stay on this forum, ask questions about RFO BASIC! there are more suited free forums for your electronic questions, do a Google search.

Nicolas

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 Post subject: Re: Calculating Capacitor Size
Unread postPosted: Fri Mar 10, 2017 1:21 am 
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Joined: Thu Mar 09, 2017 7:31 pm
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:D thanks for your reply. Please don't restrict to the inappropriate place where I posted the topic.
As to the question, can you help me answer it ? thanks in advance.


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 Post subject: Re: Calculating Capacitor Size
Unread postPosted: Fri Mar 10, 2017 1:54 am 
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Location: Paris, France
Of course I restrict to the inappropriate place. Do you usually go order a pizza at the post office, and tell them to not mind the inappropriateness? It's same here, this is a place to discuss RFO BASIC! I'm incapable to answer you, this is simply not the good place to ask.

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 Post subject: Re: Calculating Capacitor Size
Unread postPosted: Fri Mar 10, 2017 2:11 am 
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Joined: Thu Mar 09, 2017 7:31 pm
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please don't make a joke on me, please...........


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 Post subject: Re: Calculating Capacitor Size
Unread postPosted: Fri Mar 10, 2017 2:24 am 
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Joined: Tue Jan 03, 2012 9:31 am
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Location: Paris, France
This is not a joke, I am serious. Do you really not understand you are at the wrong place? Sorry to ask but are you even using RFO BASIC! in the first place?

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- Creator of the Android BASIC! Compiler


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 Post subject: Re: Calculating Capacitor Size
Unread postPosted: Fri Mar 10, 2017 2:34 am 
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Joined: Thu Mar 09, 2017 7:31 pm
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I can understand, but I am asking a question, you don't answer it. In this case, how can you blame me for posting a topic at the wrong place ? I am really puzzled.


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