Issues with a full wave bridge rectifier.

[Constructionk88]

Isnt a typical wall adapter is roughly in the 1 to 3 amp out range and an average car batter in the 500 to 800 amp range? Shouldn't that make a big difference?

 

[Nigel Goodwin]

Isnt a typical wall adapter is roughly in the 1 to 3 amp out range and an average car batter in the 500 to 800 amp range? Shouldn't that make a big difference?

No, as long as the supply can provide MORE than the load needs everything is perfect.

For example, if you connect a 1K resistor across your 12V 2A supply, then 12mA will flow. If you connect the same 1K resistor across your 12V car battery, the same 12mA will flow - the load will only take what it wants.

 

[Constructionk88]

Thanks for the clarification Nigel. Yes im new to this. This isnt for homework. Its an off hobby im trying to improve on. I appreciate the help. For most of my purposes thos is to build power supply and power regulating circuits. I dont have a broad need and going through a multitude of prebuild purchased power supplies is insanity given the short lifespans of the previous ones.

 

[Nigel Goodwin]

Thanks for the clarification Nigel. Yes im new to this. This isnt for homework. Its an off hobby im trying to improve on. I appreciate the help. For most of my purposes thos is to build power supply and power regulating circuits. I dont have a broad need and going through a multitude of prebuild purchased power supplies is insanity given the short lifespans of the previous ones.

If you're abusing them, then they WILL have a short live - you need to know what they can supply, and what the load is wanting to take.

 

[Constructionk88]

I should clarify the short life isnt due to stress from what it powers. Its 99% the result of external heat and moisture. Possibly bumping it around, ect. Mostly the outside environment.

 

[Constructionk88]

having reverse powered a transformer i had on hand(surprisingly), the new outputs are 25, 35, 41, and 47. the 25v out rectified is 19v(each is 6v- the ac prior to rectifiying). it powers the fan much more powerfully than the higher voltages??

 

[Nigel Goodwin]

having reverse powered a transformer i had on hand(surprisingly), the new outputs are 25, 35, 41, and 47. the 25v out rectified is 19v(each is 6v- the ac prior to rectifiying). it powers the fan much more powerfully than the higher voltages??

Why are you surprised?, just apply ohms law - you have a low current power supply and you're trying to take excessive current from it.

Also rectifying the AC to create DC should give you a considerably higher voltage - about 1.4 times higher - do you niot have a large electrolytic across the output?.

 

[Constructionk88]

The original inputs are common, 110v,220v,240,and 277v. They are my new outputs sonce im running the transformer in reverse. I realized the higher voltage outs have s much lower amperage than the lower vout. If i recall it was 20vdc@2.5a, 31vdc@1.2, 37vdc@.9a and 47vdc@.7a. My diodes seem to be lowering the rectified voltage. They are large power transistors. The type i dont recall but when i switched to common 1n4005 the rectified output voltage was indeed 1.414x ac in. I believe the original primary windings are the cause of the drastic change in amperage?

 

[Constructionk88]

I did place a 200v 4700uf electrolytic cap in parallel to the output but it seemed to weaken my power

 

[JimB]

What??? - have you not read the thread?.

Nigel, that was a spammer.
You must have been replying as I was deleting.

His text was copied from AAC.

JimB

 

[Nigel Goodwin]

Nigel, that was a spammer.
You must have been replying as I was deleting.

His text was copied from AAC.

JimB

I suspected it, and was planning keeping an eye on him.

 

[Nigel Goodwin]

The original inputs are common, 110v,220v,240,and 277v. They are my new outputs sonce im running the transformer in reverse. I realized the higher voltage outs have s much lower amperage than the lower vout. If i recall it was 20vdc@2.5a, 31vdc@1.2, 37vdc@.9a and 47vdc@.7a. My diodes seem to be lowering the rectified voltage. They are large power transistors. The type i dont recall but when i switched to common 1n4005 the rectified output voltage was indeed 1.414x ac in. I believe the original primary windings are the cause of the drastic change in amperage?

You're doing absolutely everything you can to ensure it can't possibly work, presumably you don't want it to ever work?.

So not using anything like a suitable transformer, and not even using rectifiers - perhaps you should try fairy dust next?.

 

[Constructionk88]

No sir it does work. Great. On my lowest voltage. 19vdc @2amps. The higher voltage outputs have very little amperage and i discovered the blower is designed to draw 7amps. Im working on getting 3a or 5a at 12 to 20vdc but im thinking ill have to rewire the secondary. I was just wondering if it was possible to do so without rewiring

 

[Nigel Goodwin]

No sir it does work. Great. On my lowest voltage. 19vdc @2amps. The higher voltage outputs have very little amperage and i discovered the blower is designed to draw 7amps. Im working on getting 3a or 5a at 12 to 20vdc but im thinking ill have to rewire the secondary. I was just wondering if it was possible to do so without rewiring

Your entire premise is still wrong, but feel free to do it as badly and unreliably as you seem to want?.

 

[Constructionk88]

Ive gotten it to work as desired sir. rewired with 2 outputs. voltage and amperage is exactly as needed. just researching how to use an lm317 to control amperage

 

[JimB]

Ive gotten it to work as desired sir.

Well that is excellent news, I think that I can say that we are all very happy for you.

just researching how to use an lm317 to control amperage

We look forward to hearing how that works out for you.

We wish you every success in your ventures in electronic engineering.

JimB

 

[Constructionk88]

I appreciate all the help. Occasionally i just need the push to figure out things for myself

 

[unclejed613]

thanks for the reply. So to some extent im guessings its not really possible to even produce a usable dc directly from a 110v main?

you can do it, but it's an extreme safety hazard to do so.

 

[Constructionk88]

Worry not. I will not, nor do i have a reason to do so. My rewired halide light transformer has surpassed my expectations. Im very happy woth the results. Ive yet to find a circuit using my lm317s to control it but i probably wont even care considering i can easily control the air in with a vent rather than controlling the speed of the fan.