LM3!* Again? Not really... but you could help...

[Luis Costa]

Yay brothers and sisters... Going to colledge maybe. Trying hard to learn things by myself. I kind got this thing i'm posting and most people know they're s**t seen and done it before.
... whats happening is that voltage drops drastically on the input terminal - shows about 0.3v. If i remove the regulator the voltage rises. I also tried to remove the capacitor before the regulator but it doesn't seems to affect anything. My first guess would be that the capacitor was over on demand from the transformer but that'd prolly burn thet coils right? I use this on a solderless pad and has been working with 0.19 Ohms. Datasheet said 0.2 but had an Eq. about it. i didn't use it.
Wating for help... thanks in advance.
maybe one'o this days i can produce some answers

 

[Bluejets]

Do you have a link to the circuit.
What is the capacity of the transformer.
What type of battery.
What voltage of battery.

 

[Luis Costa]

bluejets...! Thanks for replying. there was no battery yet. i know that the voltage drops on the voltimeter if the battery is uncharged.
The transformer is from a computer battery charger. It's low capacity 27Ohms on the secondary. I'm not sure transformers are exactly like resistors??? about 0,4A? Can't you see the bitmap with the circuit bluejets?
ty

 

[Luis Costa]

Yay brothers and sisters... Going to colledge maybe. Trying hard to learn things by myself. I kind got this thing i'm posting and most people know they're s**t seen and done it before.View attachment 25072
... whats happening is that voltage drops drastically on the input terminal - shows about 0.3v. If i remove the regulator the voltage rises. I also tried to remove the capacitor before the regulator but it doesn't seems to affect anything. My first guess would be that the capacitor was over on demand from the transformer but that'd prolly burn thet coils right? I use this on a solderless pad and has been working with 0.19 Ohms. Datasheet said 0.2 but had an Eq. about it. i didn't use it.
Wating for help... thanks in advance.
maybe one'o this days i can produce some answers

 

[cjdelphi]

What's the secondary AC voltage? 10v? (disconnect the bridge rectifier first)

 

[AnalogKid]

Also, what are the 317 input and output voltages with the battery disconnected?

ak

 

[Bluejets]

bluejets...! Thanks for replying. there was no battery yet. i know that the voltage drops on the voltimeter if the battery is uncharged.
The transformer is from a computer battery charger. It's low capacity 27Ohms on the secondary. I'm not sure transformers are exactly like resistors??? about 0,4A? Can't you see the bitmap with the circuit bluejets?
ty

I meant where did you get the circuit from and have you made changes.
You quote low capacity 27 ohms...that I afraid means nothing.
0.4A is the transformer output (depending on where you obtained that information) BUT what are you intending to do with it?

 

[Luis Costa]

the circuit was on some datasheet or something. i couldnt really find the same thing. like i said i usually use this on the pad and the pad has power source of 12v/2.5A. if you see the datasheet of texas and others there's a similar thing. without the 1mF capacitor. Theres also a chance that the package im using is burnt ( the LM317). i did say i know little about transformers of course 27ohms may not mean 0.4Amps.
Without bridge gives 12v. Diodes are 1N4007. once the LM is dosconnected everything works well. about 10.9v.

Also, what are the 317 input and output voltages with the battery disconnected?

it's suppose to be regulated. you use the potentionmeter to set the voltage.
transformer input: 230 ~. Secondary: 12v~ (10.9) with the bridge. Once i connect te LM317 the input voltage drops at 0.3v. About nothing on the output terminal.
thanks

 

[Luis Costa]

so... sorry, i noticed nobody answered. Like i said i know little of transformers and after looking around i found ferrite. so i'm using iron now.
ty

 

[(*steve*)]

If you have the pins of the regulator around the wrong way you may get this behavior.

Double check you have the correct connections.

 

[CDRIVE]

so... sorry, i noticed nobody answered. Like i said i know little of transformers and after looking around i found ferrite. so i'm using iron now.
ty

If you're implying that you made this transformer and it's (unpowered) output resistance = 27Ω then your transformer isn't going to deliver much current. In fact hanging a 27Ω resistor across the secondary winding is going to drop your output voltage by 50% and this does not take into account the 'K' of your transformer.

I suggest before you suspect the 317 I'd do some basic loading tests on your transformer. The fact that you appear to have home brewed it changes the game. If this is the case we can't take the transformer out of the troubleshooting equation.

Chris