Kris

Are you looking just for the bridge rectifiers to convert AC to DC or do you want/need regulated power supplies that put of 5, 12 and 24VDC?

Scotie

Hi Scotie

I am looking for AC to DC Bridge Rectifier for regulated power supplies one for 5 VDC, one for 12 VDC and 24 VDC. I do not want to use wallwart.

Mouser has bridge rectifiers. Start here and use the filters to narrow down your selection.

You can use one type of bridge for all your applications. The rectifier rating does not determine output DC voltage; the input AC voltage does. You should choose a bridge with at least a 50 volt Peak Reverse Voltage. The PRV does not affect the output voltage in any way.

Larry

Here's some, Digi-Key 50 volt bridge rectifiers Should cover all your ranges.

If you have to have enclosures for everything, the wall warts might be a consideration?

If you don't mind the eBay from Asia wait, several sellers have these insanely priced at 10 cents each.  In any event, you choose/specify the voltage rating of the bridge rectifier based on the AC voltage going in...rather than the downstream DC voltage.  So if the AC is 14V-18V AC coming from track or accessory voltage, the 50V rectifiers recommended above would work...or these 1000V ones would more than handle the AC voltage!

http://www.ebay.com/itm/LW-HOT...hash=item4ad29e6664#

China has become the new Canal Street. (Those of us of a certain age and from the NYC area will know what I mean.)

My opinion is that for 10 cents each, even if half of them fail out of the package, you still paid only 20 cents each for the good ones. I buy all my components this way.  Go for it!

Those would definitely be cheaper than Digi-Key or Mouser. I get a lot of stuff that way myself (some arrived in the mail today), but for some reason I always think of Digi-Key when I post here. I also get quite a bit of stuff from Digi-Key.

It really depends on how fast I need stuff.  For projects like my Super-Chuffer or Passenger Car Lighting, I buy the stuff from Digikey or Mouser.  There's a good reason for that, I need to buy a very specific part most of the time, so finding it on eBay would be difficult to impossible.

For parts that I just stock for various projects like diodes, LED's, capacitors, resistors, etc., I just look for the cheapest source.  I buy them in large lots, so I can afford to wait for shipping from China.

Rectifiers are rated in amps, and voltage. Most all are at least 50 volts. For what we do we do not need anything higher. I work on old amplifiers sometimes so I always buy higher voltage ones. The amperage needed depends on the power supply you are building amperage needs. If you centralize your supplies,really a 25 amp bridge and one transformer tap will do the whole layout. 

On my layout I run hundreds of relays off an 18 volt brick and a 25 amp bridge rectifier. With a capacitor it gives me a 24 volt DC supply,unregulated. It spares me the need to put a bridge on each relay. But you can tap the voltage for regulated supplies if need be.  I do use other bridges on my layout but as voltage droppers. 

John linked some AC to DC and DC to DC converters from China. For $3 each or less I can not see making them myself anymore soldering at the chip level. Just solder 4 wires to it turn a screw and set it with a meter and you are done. I have experimented with these and they work well. Many thanks to John for the heads up. 

With the supply previously mentioned all you would need are 3 of the units to set at the 3 voltages. 

Dale H

Thank you one and all for the explanation. Since I am still new to this I was under the impression that you get a Bridge ref and just install it with the correct voltage. I see now that I was mistaken. You need Bridge ref which gives you DC and then  DC-DC Boost Buck Converter and then dial in the voltage you need.  I remember that there are two types the one that really hot and the other one that is warm to the touch. I am looking for the one that is warm to the touch. Can anyone point me in the right direction.

Kris, this is the DC-DC boost buck converter I ordered for lighting passenger cars per gunrunnerjohn's recommendation in another thread.  Have them but awaiting other parts (capacitors and rectifiers recommended by grj) from China needed for their installation.

Whether what I bought will have any relevance to your application, I can't say.

For strictly running stuff from track power, you can use smaller components many times.  For one, you usually don't need to step up the voltage, so the cheaper and more compact buck power supply usually works.

Here's a cheap option, add a bridge rectifier and you're all set.

http://www.ebay.com/itm/1-DC-D...;hash=item2a3cdecf73

A more compact model, but it does need an input capacitor after the bridge rectifier.

http://www.ebay.com/itm/New-Mi...;hash=item27fb8a51e6

I hadn't seen those small ones before, they are really shrinking those things down with all that surface mount stuff. I won't be able to see them at all before long...

Some of these http://www.ebay.com/itm/361147264558 arrived in the mail yesterday. Put one together last night and so far so good, it works. These were not bad, also a fun project to put together. No directions, but it was pretty clear from the board where everything went, it was well marked. They were a bit larger than the DC/DC converters though. Was wanting some more AC/DC to DC converters with an LED meter installed on them like I got a while back, but couldn't find any. 

Got two kits left, was thinking about asking my grandson if he would like to try one, that would be a good learning project for him, or anyone else with kids or grand kids of age to try something like this.

Hi rtr12

I also ordered these kits(3each)and built one a couple of night ago.  Wanted a hands on learning tool.  1st assy. and it worked.  That is rare for me.  Tried to understand the purpose of the components as I built.  I have more knowledge than before, but however the 1.1 amp 30v JDT fuse I had not seen before. Of course did not have a schematic.  Can any of you guys help us out on this fuse?

Thanks

Tommy

JDT is a company that supplies various types of fuses.

Larry

Hi Larry

Thanks for your help.  My question is the purpose of this fuse?? Input Volts/Amps or output control.  Does not appear to be resettable.  This the first occasion I have seen this fuse.  Just need some info as to it's purpose or usefulness on the PCB.

Thanks.

Tommy  

stan2004 has the answer above, also much better than mine would have been, I might add. He is very knowledgeable and very helpful on all this stuff and knows a lot about it all as well. Follow and study his posts and you will learn more.

I ordered these. You don't even need a bridge since it is AC to DC. Just run it off the accessory tap of most any transformer. Don't need no Walwart. A lot of wires for nothing.

LINK 

Dale H

Hi Dale

I saw that as well that was going to my next question on the subject. But you bet me the the question. I think that would work better than the Bridge ref than to the DC to DC step down.  What about the heat that is generated from the AC to DC conversation is hot or warm to the touch?

Hi Kris

It depends on the load. From what I read the circuit can be up to 90% efficient so it does not heat up like a linear regulator. They are rated for 3 amps. John said in another post I think that  they get warm after a 1.5 amp draw. So in a 12 volt circuit they will maybe drive 20 watts. In a 5 volt circuit up to 10 watts comfortably. If you drive more than that just use more and make separate buses. I have seen these circuits before but they were never this affordable. I purchased a bunch to power Miller signs on buildings when I get to it.My new layout is not finished yet.Originally I was just going to make some 7805 circuits with a voltage dropping diode downstream to get 4.4 volts. But this is much easier and the price is right. I have some older DC to DC ones I just solder a bridge to and am waiting for the Ac to DC ones on order. Either version will work if you solder on the mentioned bridge,you can solder a 4 amp one + and - terminals right to the board,then solder the AC input leads to the bridge. These should work nicely with a lot of things I do. 

I am not an EE like John so perhaps he can explain more. I retired 15 years ago and have not kept up with all the stuff.

BTW for the 24VDC,you can get that from an 18 volt AC tap on a transformer with a bridge and capacitor. If it don't have to be regulated you can use it that way,otherwise you could use the converter. 18 VAC peaks at about 25 volts. It should be 2 volts more than the converter so you could probably get close to 24 out of it. More like 23. 

Dale H  

This may help.  I didn't want to type all this stuff in.

Understanding the Advantages and Disadvantages of Linear Regulators

Form Johns Link

A switcher is always "thinking", so the oscillator is always running.  If you have a very low load, say half a milli-amp or less, then it's possible that the linear supply might take less power.  OTOH, for any reasonable scenario, there's no contest, the switcher will win the race easily.

Dear All

Many thanks for all the replies.  John and Dale H that you for the additional information. Stan you are always on the money when it comes to this electronic stuff.

Dear Mark

What I am trying to do is  power Stan IR design with the 5 VDC. The other two are Bucks that I have purchased incorrectly and I trying to get the right VDC to power them which is 12 VDC and 24 VDC and use them some future application. I am new at this and I have learned a great deal, but I still have much to learn. If it would not be for this forum I would still staring RS draws and say to myself am I getting the correct parts what is this stuff? Now I know their are other vendors out there and what the parts do in a circuit to a  limited extent.

Dear Tom (rtr) I am still learning how to use this website. I have learned how to follow members on this website.  Any additional advise would be greatly appreciated.

I was just referring to following their instructions and advice that they post here, not only stan2004, but gunrunnerjohn, Dale H, cjack and others that post here about the electronics. I hadn't thought of using the forum's 'Follow' feature, but that is a great idea. You won't miss anything that way. Hope you got your bridge rectifiers figured out.

Hi Tom (rtr12)

I got the bridge rectifier figured out. The original idea was to get a bridge rectifier that did product the 5VDC, then another one that produced the 12 VDC and than another that just produced 24 VDC. That is not the case get a 35 V bridge rectifier and use a DC-DC Buck Converter Step Down Module then dial down the DC voltage to the needed DC voltage and check it against volt meter.  Learn something new everyday.

"Follow" feature is great because you follow who you want and see what they are replying about. If it is something you are interest about you read it if not delete it. I drive my wife crazy with this feature. "You are reading your e-mails again what is so important?  My reply is "you want me to expand my knowledge don't you?"

It has saved me some grief. IE Recently I saw some Lionel trains really cheap on $15 for a steam engine and tender at a show and there where about three of them, I said to myself great purchase. I inspected the sets and it said "Scout" on it and all kind of alarm bells where going off in my head.  I could not remember who stated to stay away from them. Once I got home I double check the information I was right a bad deal. If it was not for this forum I would have purchased them and had more headache than I needed.