plase help me... to this idea

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dilan silva

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hello everyone

i want to built AC 230V to DC 4.5V step down circuit can anyone please help me do this should i use transformer or reguator ic like LM 317...

please help me with circuit diagram

thanks

bye
 
dilan silva said:
hello everyone

i want to built AC 230V to DC 4.5V step down circuit can anyone please help me do this should i use transformer or reguator ic like LM 317...

please help me with circuit diagram

thanks

bye
Click to expand...

hi,
How much current will the 4.5Vdc supply have to provide into the load.??
What are you trying to do with this supply.?
 
This might help:

**broken link removed**

Choose the rating of your transformer to give you an output voltage of about 7V, then feed this into the LM317 and adjust the output to 4.5V.

As Eric asks, what is the output current of your circuit? The power dissipation in your LM317 will be:

(Vin - Vout) x load current

If you put in 7V and have 4.5V out, your current will need to be less than 200mA to keep your power dissipation in the 317 to less than 0.5W. If you load current is any higher, you will need a heat sink
 
Last edited:
Firstly, you need a transformer. This converts the voltage from 230V to x volts (depending on the rating of the transformer). You then need to change this from ac to dc using a bridge rectifier. The dc voltage will be about 1.4 times your ac voltage (dont ask why). Smooth this with a big capacitor - see my article above, then feed this voltage into the LM317 input pin. refer to the 317 datasheet to select what resistors you need to set the output voltage to 4.5V.

That is your circuit..
 
ok sir thank you for ur grate description & i'll try that one ok thanks onceagain

if anyone has any different please share

thanks
bye
 
Ready made 230VAC to 4.5VDC power supply: Find an old cell phone charger...5v/~700mA. A digital clock that's works on 4.5V should have no problem working on the 5.0V wall-wart. They are all over the place. I get them at thrift stores for $0.39 to $1.99 all the time. You can't build one that cheap. If you want closer to 4.5VDV, just add a 1N400X diode in series with the + lead.

Ken
 

u mean its not any problem give 5v to 4.5v need circuit .. actually is there no any heat or chip burning situation?
please sir reply i'm very happy with this idea

thanks
bye

other ideas is also welcome
 
Most microcontroller chips that can operate off of three 1.5V batteries are actually designed to operate at around 5V. I doubt that the 5V will heat up or smoke anything. Like I said, if you want a slightly lower voltage you place one silicon diode in series with one lead from the 5.0V supply and get ~4.4VDC to your clock.

Ken
 

sir can u give me suitable value of the silicon diode please

thanks a lot
bye
 
Any diode 1N4001 through 1N4007. Or 1N914 or 1N4148. Many others but you should be able to find one of these.
 
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