Two bridge rectifiers on a centre tapped transformer?

I don't expect you will see this post, because I think you have blocked google groups. But this circuit will not work as you expect. Rather than trace current, try figuring out the voltages. That might be more clear.

You have two input terminals labeled "12", so it's hard to differentiate them verbally. So I'm calling the top one 12up and the bottom one 12dn. Actually, they don't need to be considered. The contradiction in your circuit can be seen just by considering the 0 terminal. When 12up is positive, the 0 terminal is connected to the lower end of the load through the upper bridge, with current flowing from the load to the 0 terminal. At the same time, the 12dn terminal is negative wrt to the 0 terminal which is connected to the load upper terminal through the lower diode bridge.

What, what, what??? The same terminal is connected to both ends of the load at the same time??? How can that be?

To understand your circuit better, try connecting a load on the output of each bridge. No common connections, other than the inputs. Now consider the voltages on each load and the voltages between the two loads.

There are two problems with your idea. One is that you can use two diode bridges in this way, you can't. The other is the need. Your two diode circuit with the center tap transformer shown, will give a 12V output. You can use the full transformer with a SINGLE diode bridge and use the entire secondary winding at the same time... but you will get 24V output. If you want 12V output with a bridge, you need a

12V transformer.

No, you will get 24V rectification. Only the LHS 2 of the top 4 diodes will be conducting, and the RHS 2 of the bottom 4 diodes. The rest will be entirely superfluous.

You need to get into LT Spice. It's free. A man of your claimed IQ should have no problem in confirming my presumption, or even proving me wrong.

If you want 12V then use:

It doesn't make full use of the copper so you may have to down-rate the transformer a little.

For different topologies:

And whether filtered or unfiltered, the output is *unregulated*.

The output varies as a function of the load current.

Slapping a regulator on the output, makes an output suited to driving a digital logic circuit. The regulator can be an SMPS (efficient) or a linear regulator (inefficient). Linear regulators are easier for hobbyists to assemble.

And while just about every web page shows "1N4007" as The Diode, no, there are other choices you can buy. The reason a lot of 1N4000 series diodes get used, is because hobbyists can buy a bag with a considerable number of them, for not a lot of money. But you can also get wafer-style full wave bridge rectifiers, that will plug into your pegboard. This handles a slight bit more current. The reason I picked this, is I used something similar in my amp for the computer speakers.

Paul

Yes and the switch mode type can cause a lot of interference if one is not careful but they are efficient by comparison with a series regulator. You can even end up with higher voltages than you started with. There was an early example in a Sony Cassette deck I had. It ran on5 to 6 volts, but the supply rails inside were 24 volts. A device marked Fuji did the work and never broke a sweat.

Brian

It would be most helpful to understand what Mr Hucker, AKA Kinsey, is trying to do.

Probably not. He's a cantankerous half-wit who shouldn't be taken seriously. There a strong argument that he should just be ignored - this user group would be a better place if he didn't post anything here at all.

Isn't that obvious? He wants to improve the efficiency of a 98% efficient transformer.

There is nothing you can do to increase the power if your load is resistive - but if it is smoothed with a capacitor, there might be.

Using a choke between the rectifiers and the first smoothing capacitor will even-out the current peaks through the transformer windings and reduce the losses which are proportional to the square of the current. You may then be able to run the transformer at a higher current than the 'official' rating, which is usually specified for peaky rectified current.

The output voltage will then be approximately the RMS voltage of the waveform (minus diode drops, the transformer winding resistance losses and the choke resistance losses), not the rectified peak voltage. (minus diode drops and somewhat larger transformer winding resistance loses). Whether this ultimately equates to more *power*, rather than just more current, will depend on the parameters of transformer and choke.

Another way to increse the power handling of an particlar size of transformer is to increase the frequency. This may not be practical for a mains transformer - and you will soon run into greater losses from eddy currents in the core at higher frequencies - but it is commonly used to reduce the size and weight of transformers in aircraft.

Average is 2/pi times peak, which is a bit less.

Power handling of a transformer or resistor or inductor improves with air flow or heat sinking. They are usually specified in still air.

He's a civilian, not an actual commander?

If I were named Hucker, I might shop around.

He is a middle aged completely unemployable welfare bludger who has never ever had anything to do with any military system.

Maybe he has a uniform and marches around and salutes and stuff.

I was in the US Navy for a week. Parts of it were interesting but I didn't decide to stay.

mandag den 27. marts 2023 kl. 23.36.23 UTC+2 skrev John Larkin:

So two bridge rectifiers walk into a centre tapped transformer bar...

Your turn...

Nope, he is actually into running around stark naked, quite literally.

He never even got close to that. The best he ever managed was doing the tech in a school for a while and stuffing spam thru letter boxes.

What about a clown uniform?

Commander is a civilian award. CBE: "Commander of the Order of the British Empire". But you're not allowed to style yourself "Commander <name>". JG Ballard was offered the medal, but turned it down for that reason.