Ok, I need a diode bridge to change 110 ac to 110dc.. So I plug it in and go..

Hi Everyone,
 I really need some smart person with common sense to answer this... I just want a very simple easy way to plug into a wall socket and transform the 110AC to 110DC...I will be using this for a very large hydrogen generator... very low amp draw.... I know I need a diode bridge with maybe filters before and after the bridge...   So, now I need to put that together... I can not find a site that has one premade...   So, I would be very appreciative to anyone that can offer a web site for parts with part numbers and a diagram or instructions to put it together..   I am a Journeyman Carpenter for anyone that needs advice..  Thanks in advance.    I would be willing to purchase it from anyone that wants to make it for me..

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U can do all the math u want but on tht 25 amp rec the vd is only .07 so u dont gain cause its 50 volt rec ur bot gona blow it cause its 25 amp u only loose the voltage drop per coponet yall remind me of bunch of engineers i work with with pop off all ther silly numbers while ive done finish the circuit have it rumning before ther lips can stop movm this has got ti be the stupidest answers and quistions obviosly if hes uavn trouble with rectif 110 do u thnk these are suitable answers for this man

man first quistion i ever answerd brothr i dont no what ur doing with hydro but if u cant manage tht u need be careful go to radioshak pik up 50 volt 25 amp bridge rectifer for 1.50 and tax wire ur 110 into ac side the positiv and neg is ur outgoing dc iy will drop about .07 of a volt so ur gona get 109 prolly do it all time and put loads on it for shory periids u will proly need add heat sink folows radioshaks directions they help yah rest way

smithdyrs1 year ago

You are asking the wrong questions. In any circuit it is the load that must be considered first. Think about it, you got a single plug 120volt6 at 60 cycles a second yet you plug devices of a wide range of power and they all work. You need to determine how much current your load will draw. It will vary according to the size and distance of your plates, Also how pure you water is. when you know that then you find what voltage or amps you want. I have no idea which but I would guess the answer would determine the speed of the process and how much energy will be wasted in heat. Then plug these in ohms law and you will have a solution that will not blow a fuse or waste time in ht e process. Its the load ie the resistance of the water that determines the current ant voltage. Don.t get huge up on any ripple in you dc. It not going to hurt and could help. think of it as shaking the molecule apart. Just a guess there but the amount of ripple from even a half wave rectifier shouldn't cause any problems. I stress its the load that determines the design of any power supply.

JimFlo8 years ago
Easy to build IF you are sure thats what you need, except when you rectify 110vac you will not get 110vdc out. Its very early and I am doing the math in my head, but you would get a hair over 77vdc usefull  output? RMS 0.707, or am I still asleep guys? Throw a fuse in the circuit before the bridge, a filtering cap across the DC outputs, and slide a current limiter in there by the cap...
May I ask for a specific or two? How much do you want to produce, residential, commercial, or farm, and why? There may be better ways depending on those variables.
Um... I think you got something backwards there Jim.

The peak voltage of the AC waveform is 21/2 =1.4142 times the RMS value, and the DC out of a full bridge type rectifier is going to be close to the peak value, circa 156 VDC output  for an RMS value of 110 VAC input.

Also I'm assuming there's a big filter capacitor, so that the ripple is small, approximately ΔV = (I*T)/(2*C), where I is DC load current, and T=(1/60) s.
It was very early, before coffee, and I am still doing the math in my head, but I don't think so. A bridge rectifiers effective output voltage will always be less than the peak value of of the AC voltage input. 1.41 is the inverse of 0.707, I was going from peak (110vac) down. Anyone want to double check us?

Anyway, BBOYDEN read these links on rectifiers when you get bored.

If you throw out a few more details on the generator you will probably get a lot of suggestions. 
I think the lab results are backing me up on this one.  See picture.
bboyden (author)  Jack A Lopez7 years ago
Hi Jack...
 I know it's been awhile since I posted this... but looking back to get further help I notice your picture is showing 5 small electronic things... I am trying to change the 110ac... to 110dc.. I purchased a bridge rectifier 10amp 1000volt... 1ph.
then I also purchased a Resistor 2K ohm, 70 watt.... I installed the bridge and plugged in the wires.. I tested the power out and it tests as dc... I think?  anyway I plug the power out into the resistor and then nothing happens.. nothing comes out.... I noticed that one advice I got, I was told I could use a light bulb on a fixture... so I did that instead of the resistor ... well I did that and the light came on?   I thought it would have to be grounded for that?  anyway... please help me.. I just want to change ac to dc... 110 volts or anywhere around that... thanks for any help..
Hello Bryan,

I have seen the questions you have asked about building some sort of power supply for the purpose of splitting water into hydrogen and oxygen.

It is puzzling to me why you want such a large voltage, something around 100 V DC, when the actual amount of work required for splitting water at room temperature is something like 2 eV per electron.  That is to say you only need a potential of around 2 volts, and any voltage above that is likely going to just go into ohmic heating of the water. 

If you want to make more hydrogen and oxygen, faster, the usual trick is to just increase the surface area of your electrodes, or build more cells.

gmoon JimFlo8 years ago
Jack A L. is correct here, JF.

RMS (Root Mean Square) is the average, effective voltage (EMF, electromotive force) of a sine wave. A 110V line is measured as RMS, so it's ~0.7 of the peak voltage. The peak voltage of a 110V main is 110 * ~1.4, or about 155V.

When you rectify, you simply shift the negative wave form to the positive--it has the same average voltage. It's now "pulsed DC," but it's still very "wavy" (despite the waviness, it's no longer AC since it's not + and -)

However, when you add filter capacitors to remove the waveform, those reservoir  caps can now charge up to the peak voltage, and hold it (close to the peak, anyway.) So yes, you'd get approx 1.4 times the RMS voltage by rectifying and filtering AC (somewhat less than 1.4X in practice.)
lemonie8 years ago
You want an arrangement like this:

But you can find bridge rectifier units in a lot of electrical appliances, e.g. old TVs. Why do you want 110V with "very low amp draw" - wouldn't much lower voltage do it for you?

You can also just buy a bridge rectifier from Ratty Ol' Shack for 3 bucks. Wire it up according to the diagram on the package, and you're good to go. Add a wall dimmer (rheostat) on the AC side, and you get variable DC output.
bboyden (author)  RavingMadStudios7 years ago
 I know it's been awhile since I posted this question but I never got it going... I purchased a bridge rectifier 10amp 1000volts 1 ph.    and a resistor with a heat sink.. 2k ohms 70 watt so anyway.. I hooked it up and it shorts out if I just run with the bridge rectifier... I do use the dimmer switch before it on the ac side.. so shorting out... then I tried with the resistor and still don't work.. any ideas?  thanks.

 boydenbryan@yahoo.com or reply
Sorry, I'm at a loss. If you're getting 110 DC out of the rectifier, my best guess would be the resistance of the water, but that's just a guess. I've only used this kind of setup to run DC motors before. Hydrogen production is outside my experience, so I have nothing to contribute to the back end of the system.
bboyden (author)  lemonie7 years ago
Hey Lemonie,
 I purchased the bridge rectifier 10amp 1000volt 1ph.  hooked it up and it works, it's putting out, but then I put the hot wire into the resistor 2k 70 watt and nothing comes out???? it has a heat sink but thought that would be a good thing???? I still need help getting this together... please help me.. in just want the dc out of the 110ac...
    I purchased the parts from Galco... nice chocolate bar..wow.  anyway did I get the wrong things?  
 Thanks for all your help...
Bryan.................  boydenbryan@yahoo.com or reply..
lemonie bboyden7 years ago

  as I said previously clean low-mineral water is a poor conductor of electricity, have you added any minerals (e.g. bicarbonate) to the water, have you measured it's resistance?

bboyden (author)  lemonie8 years ago
Thanks Lemonie, I do thank you for the diagram.. as it is. I understand that you can create lots of hydrogen two ways... low volts with high amps... or High volts and low amps... the later will save your plates from wear...  Thus, High volts and low amps... I would be sooooo happy if you could please draw out another diagram showing the connections to the bridge.. do you connect to the center two or outside two?  which ones get the 110 and which put out the DC?   Also if I should connect a resister or filter what size and where should I put it..  I need details...  where do I purchase one.. and whats the best what to connect one.. I'm willing to pay for any help on this stuff..
lemonie bboyden8 years ago
The rate of electrolysis is proportional to the current flowing through the cell, this high/low voltage bit should largely be ignored as it's not right.
2 H2O(l) → O2(g) + 4 H+(aq) + 4e    E= -1.23 V
2 H+(aq) + 2e → H2(g)    E = 0.00 V
You only need small voltage to drive this, hydrogen production is proportional to those e- (electrons) going through it, higher voltage will increase current flow.
Anyway, your AC supply is marked with the tilde (IN ~), the DC out is marked + and - OUT.
If you put a resistor in line you'll have some / most of your voltage across that, which is where I'm asking about won't low voltage do? It depends upon your cell - clean low-mineral water is a poor conductor of electricity. If you don't live in a hard water area you may find you don't need one, but I'll diagram you anyway.


bboyden (author)  lemonie8 years ago
Thanks Lemonie..
its a bit confusing because the diodes seem to be 'backwards' since conventional current (+) flows in the direction of the arrow...+ to -, but since the bridge goes between the source and the load, it really does point toward the DC +.

Seconded - lots of sites mention using lower voltage dc at higher current to electrolyze water.  I've seen anywhere from 6-12 volts for small operations.  Some advocate using a pulsed dc signal, I call it bunk, to increase yield.  You only get out what you put in...
Well yes, but it was the first un-annotated diagram I came across this morning.
I don't think this is best, but "I need a diode bridge" is answered well enough.

there is a  little problem with this design. He must make sure his hydrogen production device has enough resistance. If you just plug this in a walloutlet and put the + and - wires in a tank of water, it is going to blow a few fuses (trust me, I tried something like this).

You could add a resistor to any of the wires just to make sure no fuses are blown, but this would lower the voltage in your watertank. Or separate it from your poweroutlet by adding a transformer between your wall-outlet and lemonie's circuit. (make sure your transformer has enough resistance)
Re-design8 years ago
Use an isolation transformer and you can make this a little safer.  Not much but some.  Connecting a bridge or diode to the wall socket is very risky.

You can make an isolation transformer using two 24 or 12 volt step down transformers.
bboyden (author)  Re-design7 years ago
Hey, I was hoping you could explain this method a little better.. I'm still trying to change the ac to dc... I purchased a bridge rectifier 10amps, 1000volts 1ph
and I also purchased a Resistor 2k ohm, 70  watts.....  Ok I hooked the hot dc coming out of the bridge into the resistor and nothing happens??? I tested the wires coming out of the bridge and it is hot...  once I try to run it though the resistor it don't work.. I then tried to run it through a light fixture.. and the light came on... that is just the hot wire or pos. wire.. in and out of the resistor into the hydrogen generator...  I feel lost so any help would be great... thanks for any time to help me...  boydenbryan@yahoo.com or just reply.. thanks.
bboyden (author)  Re-design8 years ago
Thanks so much Re-design... you have been a big help...
bboyden (author)  Re-design8 years ago
Ok, where would I put the step down transformers?  how are they installed to the set up... AC 110 to the transformer, then to the bridge, then to ??
Go to this guestion.  Down about mid way I posted a pdf diagram that should answer all your questions.  I would not hook it up any other way.
This kind of direct on-line circuit is deprecated, because it draws DC from the utility, which increases transformer losses. That's one of the reasons that we use isolating transformers and reservoir capacitors.

bboyden (author)  steveastrouk8 years ago
So, How would your recommendation be hooked up?  
With an isolating transformer for a start: Direct on line is dangerous stuff.
Then put a nice fat capacitor on the output of the bridge.