regulators and rectifiers?

Discussion in 'General Electronics Chat' started by Mathematics!, May 13, 2009.

1. Mathematics! Thread Starter Senior Member

Jul 21, 2008
1,022
4
I have a bridge rectifier who's working peak reverse voltage 100V
and RMS reverse voltage is 70V. I am wondering if I can use this retifier in place of the KBP210 in this video.

And I don't have the LM317L regulator but I have the LM317T regulator can I use this in place of the LM317L.

I am looking at the LM317T characteristics and it say's max input-output voltage differential 40 V what does this mean? Is this just saying the difference between the input and the output voltage can be no greater then 40 volts.

Problems and questions:

My silicon bridge rectifer radioshack part 276-1152 has a max rating of 70 volts RMS so will this burn out from a 90 volt 20 hz AC pulse on a phone line? Is their anyway to fix this so the rectifier never gets more then 70 volts?

If you look at the video they are using 2 resistors 510 and 240 ohms.
Is their any reason on these values for the regulator ?

For the bridge rectifer does it matter which AC leg I use for the green and red wires or can I just put green on any of the 2 AC input legs of the rectifier and the red on the other one?

I am also wondering what the current down the green and red wires is usually because the regulator can only take 1.5 amps or less?
I don't think current is going to be a problem but if anybody knows what the range of the current typical is down the wire please let me know.

Also for the regulator the input voltage is going to be around 48 v DC and 90 v AC when ringing occurs. Will this damage any components like the regulator?

Note I have also regulators part 276-1771 , part 276-1770 these regulators are for producing steady 12 volt , and 5 volts. But they have a max input voltage of 35 v. So I think if I used these I would need to drop the voltage before supplying it to the retifier. But the LM317T does not specify a max input rating only a power dissipation of 15W and input/output voltage differential? So I am thinking it is saver to use the LM317T in place of the LM317L? Anyway if I knew the typical current on a phone line I could figure out the max voltage from the power dissipation of 15 watts I believe? (Pmax/I =Vmax)

Thanks for any help in clearing up these questions

Last edited: May 13, 2009
2. Mathematics! Thread Starter Senior Member

Jul 21, 2008
1,022
4
Does anybody have an info on these questions?

3. thingmaker3 Retired Moderator

May 16, 2005
5,072
8
This is probably illegal. I suggest you not do it.
That is indeed all it is saying.
Put two of these illegal gizmos in series. Only, don't because it is probably illegal.
The maximium available current is determined by the supply. The actual current drawn is determined by the load. If your load is more than 32Ω, you will draw less than 1.5A. http://www.allaboutcircuits.com/vol_1/chpt_2/index.html
Are we talking about the regulator with the max differential voltage of less than half the ringer voltage? That regulator? It will only be damaged if the rectifier doesn't blow first. This is all academic, though, since the activity is probably illegal and should not be tried.
And an output range of 1.2 to 37 V.
I'm sorry, but the universe does not work that way. The phone company's voltage is well regulated. The current from the phone company is equal to the voltage divided by load resistance. Most legal phone equipment has an off-hook resistance of 150Ω, give or take. You can do the math for current drawn. After doing the math, ask yourself what size breaker or fuse might be protecting the phone company's equipment.

4. Audioguru Expert

Dec 20, 2007
10,513
1,169
When you try to steal power from a phone line then it goes "off hook". After a few minutes without dialing the phone company will disconnect it and send a technician to fix it. Then you get fined for stealing their power.

Besides, the lousy old RadioShack parts won't survive anyway.