Author Topic: diode bridge  (Read 4008 times)

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Offline dsesmgTopic starter

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diode bridge
« on: December 21, 2008, 01:41:40 AM »
Hi, I am trying to make a diode bridge according to this website.http://www.eidusa.com/Electronics_Kits_diode_bridge.htm
There is a diode bridge that is named "model A". That's what I want to make for my various applications.
I need to convert AC from the power grid into DC but I am not sure about the schematic(Convert AC into DC).
After the transformer, the schematic shows 4 diodes connected.
but, I don't know what type of diodes should I use.
According to the picture, it looks either 1N5406 or 9440.
In the middle of the website, the kit is 1N5006, 1N4007.
Could you tell me Which diodes should I use and how can I connect them?

Offline dunk

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Re: diode bridge
« Reply #1 on: December 21, 2008, 04:20:03 AM »
you want a Shottky diode.
look at the datasheets of potential Shottky diodes and make sure the voltage and current they are capable of handling exceeds what you expect to draw from your circuit.

dunk.

Offline paulstreats

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Re: diode bridge
« Reply #2 on: December 21, 2008, 06:59:05 PM »
Many places that stock diodes for this purpose call them "rectifier diodes" (they are schotty but are made purposefully for rectifying ac to dc)

Offline dsesmgTopic starter

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Re: diode bridge
« Reply #3 on: December 22, 2008, 02:44:26 AM »
thank you.
Could you recommend me a link to Scottky diodes?
I can't find any of these at my country's websites.

Offline Spoil9

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Re: diode bridge
« Reply #4 on: December 23, 2008, 12:43:58 PM »
How much current are you looking at? Since you mentioned you're in a different country I assume you're using 220v?
Almost any diode that meets the voltage and current requirements for your project should work.
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Offline dsesmgTopic starter

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Re: diode bridge
« Reply #5 on: December 23, 2008, 05:32:32 PM »
hi, spoil9
I would like to make both 1A and 3A diode bridges.
yes, I use 220V in my country.
Ok, then I will try to look for more diodes that meets 220V and 1A, 3A.
Can I use use same diodes?
I mean in this website http://www.eidusa.com/Electronics_Kits_diode_bridge.htm, it looks like 4 pieces same.
I heard it is extremly dangerous to play with AC current.

Offline ArcMan

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Re: diode bridge
« Reply #6 on: December 23, 2008, 09:18:17 PM »
I recommend just buying a full-wave bridge rectifier.  It's a small 4-pin package that contains all 4 diodes connected as a full-wave bridge rectifier.  Very convenient, cheap and plentiful.

Offline dsesmgTopic starter

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Re: diode bridge
« Reply #7 on: December 24, 2008, 07:23:22 AM »
thank you for letting me know that!
Could you recommend me a link to a supplier who carries commercially available full wave bridge rectifiers?
Do they come in different voltages such as 12v, 24v etc?


Offline ArcMan

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Re: diode bridge
« Reply #8 on: December 24, 2008, 11:00:18 AM »
Most every electronics supplier carries these.  I'm not sure which country you're from.  In the U.S. - Mouser, Newark, Digi-key, ad infitum.
Yes.  They do have various maximum voltages (anywhere from 50 to 1000+ volts).

Offline Spoil9

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Re: diode bridge
« Reply #9 on: December 24, 2008, 12:37:16 PM »

Do they come in different voltages such as 12v, 24v etc?


In order for you to get 12 or 24 volts, you would need some type of transformer. These diodes and the full-wave rectifiers only convert the AC sin wave into a DC voltage. They do not change the voltage.
(Not taking into account the small voltage drop due to inefficiencies)
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Offline dsesmgTopic starter

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Re: diode bridge
« Reply #10 on: December 25, 2008, 04:27:07 AM »
oh.. i see.
then, I better use a transformer to convert AC power into DC power and connect some type of bridge rectifier right after the transformer.
My intension is to make a circuit of bridge rectifier by myself so I figured this circuit would be suitable http://www.eidusa.com/Electronics_Kits_diode_bridge.htm
But, it doesn't show any voltage level...
Most of my applicatios would be controlling small DC items such as tiny solenoids, motors etc.. so those items will be needing between 12VDC ~24VDC.
I can understand that i must use a transformer. But, unfortunately I don't have any knowledge how to use DC power(from transformer) to make it at certain voltage level such as 12V, 24V.
Currently, I am trying to control a stepper motor but I think I need to do something to power it before controlling it.
Its specification is like this.
*Voltage    *Current   *Holding torque  *resistance  *Inductance
   24V            2A               16kgf            2.5ohm        4.9mh

In this case, the current it would draw is 9.6 as I = V/R.
Could you please advise me how to approach to this specific case?

Offline ArcMan

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Re: diode bridge
« Reply #11 on: December 26, 2008, 02:52:08 PM »
A transformer does not convert AC voltage to DC voltage.  It changes AC voltage from voltage to another - for example 120VAC to 24VAC.

No offense, but I suggest that you avoid building a power supply until you understand basic electronics.  There are many good books out there (just search this forum).  Start with something safer for now.  Stay with batteries and low DC voltages like 5VDC and 12VDC.  If you need something that plugs into the wall, buy a commercial unit.  Your local fire department will thank you.  ;)

Offline dsesmgTopic starter

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Re: diode bridge
« Reply #12 on: December 26, 2008, 09:15:55 PM »
ok, i will do that.
 thank you.

 


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