I am doing a simple electronics project and need to convert 120v ac to dc. I know that you can do this with a bridge rectifier, but i need schematics and instructions in detail.

 

The first instruction would be to use an isolating transformer for safety, at least if you want any assistance from this forum.

Frankly though, I don't think anyone is going to give you "detailed instructions and schematics". If you need this level of detail, it will be hard to guide you through this safely - that's not a responsibility I would take upon myself: others may disagree.

 

Use a simple wall wart; they're cheap and effective.

 

search for "bridge rectifiers" under google images

 

Really, a "wall wart" or plug supply is the easiest way to start making a small DC supply. Many of them are unregulated, but that is OK; you simply add a reasonably large capacitor, a semiconductor regulator (fixed or adjustable; the adjustable variety usually requires a pair of resistors to set the voltage) and a smaller capacitor on the output. You will need a plug supply that has an output voltage several volts higher than your desired output voltage.

However, you need to tell us what voltage and current you will be needing for your project.

It would help us to help you a great deal if you would put your location in your profile - that way we might be able to suggest appropriate suppliers for components that you will be needing.

Click on the 'User CP" link on the menu bar near the top of any Forum page.
On the next screen, click the "Edit Your Details" link on the left.
Fill in the blank under "Location - where you live" - country and state or province is fine; you don't have to get overly specific.
Then click the "Save Changes" button near the bottom.

 

Many wall warts have the large capacitor. The rated voltage applies if you have the rated current, otherwise they are all over the place voltage wise.

Wall warts in general come in every possible configuration, including just a simple transformer. Advance types may have a precisiion regulator. Most are simple transformer / diodes / capacitor arrangements, but don't assume anything until you've really looked it over.

 

There you sergant wookie
i just made an accound last night, and i appreciate all of the answers that i got so soon. Ijust need regular american house voltage (120 volts) in DC.

 

Glad you got your location updated, Jackcat.

Tell us how much current you need at 120v?

It would be a very good idea to tell us what you are wanting to do with the 120V DC. This is a potentially dangerous voltage.

You will need to use a transformer to isolate the circuit from mains power, as otherwise it will not be safe.

120VAC actually has a peak-to-peak voltage of ~169V. You cannot simply rectify 120VAC to get 120VDC.

 

Wookie made the point, a 1:1 transformer will create a minimum of 180VDC, possibly more. This is because power supply circuits use the peak value of the sine wave, not the RMS.

If the current is low enough it is possible to hand wind a simple transformer, and adjust the winding ratios to something that will give you what you want. I'm thinking of a large toroid, but there are several ways to go about this. As Wookie has also pointed out, this is a dangerous amount of voltage, and some schools of thought suggest DC can be more dangerous than AC.

Wookie, I feel like all the time I am following you! I am not a stalker!

 

On a daily basis i work with 9,000 volts. 120 is low voltage. I need to charge a set of capacitors at 2,000 volts DC. I will do this by using a MOT, (microwave oven transformer) which is NOT current limited. I can go online and purchase 30 microwave oven diodes for around $15.

 

do what i do. go on craigslist and get tons of free microwaves and salvage the diodes, caps, transformers,etc.....

 

The level of expertise you are showing vs. the hazard of the project are not comparable.

I must therefore close this thread. You may appeal to other moderators, but I suspect there will be a consensus on this.

This decision is based on our Terms of Service, which in part says the following...

Forum members must not knowingly provide any information that may adversely affect another member; this includes, but is not restricted to, information that may potentially result in injury, death, damage or destruction of property and possessions. The administration takes this matter seriously and has the right to remove any contentious content