Hello Im Ahmet Im 15 so I have a digital table clock it needs 9v I have a power supply that converts 220v to 9v but its AC and the clock needs DC I have 4 diodes and a capacitor. The diodes value is 1N4007 and the value of capatsitors is 100 mF 50v and 10 mF 50v with these components how can I get a 9v dc outpuy please help

 

If you feed the 9V to 4 diodes connected as a bridge rectifier and smooth it with a capacitor you will get about 11.3V. This is the peak voltage of 9V RMS minus two voltage drops. This is probably too high for the clock.

You could use a 9V regulator (perhaps a 7809) following the above arrangement to reduce down to 9V for the clock.
Alternatively you put three more 1N4007 diodes in series with the supply to drop 2.1V and again get down to 9V.

 

If you feed the 9V to 4 diodes connected as a bridge rectifier and smooth it with a capacitor you will get about 11.3V. This is the peak voltage of 9V RMS minus two voltage drops. This is probably too high for the clock.

You could use a 9V regulator (perhaps a 7809) following the above arrangement to reduce down to 9V for the clock.
Alternatively you put three more 1N4007 diodes in series with the supply to drop 2.1V and again get down to 9V.

So my diode and capacitor values are ok right if they are which capacitor should i Use 100mF or 10mF and can i jusy use a resistor.

 

Hopefully you have a transformer in between the line voltage and DC...

 

Hopefully you have a transformer in between the line voltage and DC...

Unfortunately I dont have a transformer

 

You said you have a 220VAC to 9VAC power supply. Does it have a transformer?

 

Yes you do, the 9V AC supply is a transformer.

Bob

 

You said you have a 220VAC to 9VAC power supply. Does it have a transformer?

I have this.

 

I have this.

That picture indicates that the power supply is DC output, not AC output as you previously stated. Are you sure you have AC output? Have you measured the voltage with a meter? (best to measure in both AC mode and in DC mode.) If you're at all uncertain about the ratings and you don't have a meter, post a picture of your actual device (not a picture from an ad or online listing.)

 

That picture indicates that the power supply is DC output, not AC output as you previously stated. Are you sure you have AC output? Have you measured the voltage with a meter? (best to measure in both AC mode and in DC mode.) If you're at all uncertain about the ratings and you don't have a meter, post a picture of your actual device (not a picture from an ad or online listing.)

 

that's 9V DC output on that sticker



Your power connections are here:

 

that's a 9V DC output on that sticker

But why is there there 3 input power cables my 9v dc adapter has 2 output what should I do?

 

We do not know where the 3 wires go to. The red and black wires on the left side say DC+ and DC-.

 

those three leads are possibly for buttons... no way of knowing without actually looking at the entire device.

 

We do not know where the 3 wires go to. The red and black wires on the left side say DC+ and DC-.

İ connected the wires but it's not working

 

those three leads are possibly for buttons... no way of knowing without actually looking at the entire device.

Those 3

those three leads are possibly for buttons... no way of knowing without actually looking at the entire device.

Those three wires go to a transformer but the transformer is for 110v

 

those three leads are possibly for buttons... no way of knowing without actually looking at the entire device.

So overall I have 9v dc adapter when I connect it to the watch it doesn't work also there is a transformer but its 110v to 9v and I have 220v

 

those three leads are possibly for buttons... no way of knowing without actually looking at the entire device.

Hello?

 

Hello so after some help I realized my adapter was AC to DC I have 9v dc output and the watch has 9v dc input but when I wire it, it does not seem to work the watch has another power input with 3 cables connected to a transformer since the Item was bought in us and I am in a different country with 220v when I plugged it there was smoke coming out I quickly unplugged it most probably the transformer was damaged but in this case we dont need the transformer.

Any help on how to make the clock work?

Mod: Merged your new Thread.

 

You showed the photo of a power supply that produces 9VDC when its input is almost any country's voltage. But you took it apart and did not write down where its 3 wires were connected. Then you guessed wrong and it blew up. The circuit for the clock also might nave been blown up.