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Participant

Join Date: Nov 2011
Posts: 4

# Designing an Electric Circuit

03/17/2012 8:05 AM

how can i design an electric circuit which can produce 5volts dc from a 240 AC supply

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Guru

Join Date: Dec 2010
Posts: 1244
#1

### Re: Designing an Electric Circuit

03/17/2012 8:45 AM

By learning about electronic circuits and supplies. Start by looking at the internet...

http://en.wikipedia.org/wiki/Power_supply#DC_power_supply

But you have asked a question like "how can I design something that flies?" - and the first decision is "midge insect size" or "Saturn V moon rocket size" or "paper glider". It makes a great difference to how it will be done.

Also, the quality of the DC needed depends on...

...........if you just want to charge a battery or vibrate a gong or, more demanding, supply a sound pre-amplifier.

There is also an important personal safety question - most DC supplies fed at 240V AC have transformer isolation for safety - but the simplest/cheapest design would not have that isolation and could not be earthed/grounded for extra safety.

Putting a "solar cell" under an electric light would do the the job for a small power - and would be safe. Several cells from scrapped light-powered pocket calculators would be needed to get about 5 volts.

67model

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Participant

Join Date: Nov 2011
Posts: 4
#2
In reply to #1

### Re: Designing an Electric Circuit

03/17/2012 9:08 AM

ok the circuit is to be used to charge a battery . and the circuit should be made wth components like the DIAC,TRIAC,thyristor ,resistor, capacitor,and others that may be neccessary

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Guru

Join Date: Dec 2010
Posts: 1244
#3
In reply to #2

### Re: Designing an Electric Circuit

03/17/2012 9:41 AM

I tried to get the idea across, but I feel it has not yet reached your brain.

Is this a watch battery or an electric submarine ship battery?

What type of battery?

What maximum charging voltage and current? Usually written on them.

Some types explode if overcharged, apart from failing quickly, and shower you with poisonous substances. A designer of battery chargers I knew got injured by a battery, a faulty contact sparked and ignited the hydrogen gas produced.

A 10 amp diode [on a heat-sink] in series with a 1 kW space heater resistance (fire-bar) would charge most batteries in the domestic world (about 2 amps r.m.s. and up to 300V!), but would over charge most domestic items.

It would not be safety isolated.

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Guru

Join Date: Apr 2011
Posts: 6671
#4

### Re: Designing an Electric Circuit

03/17/2012 10:35 AM

Here is a circuit simulator with which you can design and evaluate circuits. http://www.falstad.com/circuit/

Also, 67Model is providing good advice, reread it.

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Location: AM-51, Deen Dayal Nagar, Gwalior, Madhya Pradesh, MP 474001, India
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#5

### Re: Designing an Electric Circuit

03/17/2012 7:06 PM

Use a stepdown transformer of 12V, PCB, 1/2/4 diodes 1N4007 for rectifier, filter capacitor 1000uF 25V and 0.1uF 100V and LM7805 regulator. You will also require a PCB, Connectors an wiring cord and some PCB soldering tools.

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Prof. (Dr.) Shyam, Managing Director for Sensors Technology Private Limited. Gwalior, MP474001, India.
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Guru

Join Date: Oct 2008
Posts: 40066
#6

### Re: Designing an Electric Circuit

03/18/2012 10:51 AM

Do your own homework. CR4 is not a homework cheat site. While some here might relish the opportunity to sharpen up old rusty skills by working the homework problem, consider the following and consider it well. If you cheat on your homework by using someone else's answers, you are only cheating yourself, because the purpose of any homework or other academic assignments is to help you learn - by practice, repetition, and self-discovery.

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### Users who posted comments:

67model (2); engmas (1); lyn (1); Shyam (1); truth is not a compromise (1)

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