DC power problem

Discussion in 'The Projects Forum' started by kiranr, Jun 5, 2009.

May 1, 2009
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I have hooked up a circuit(not very big) to a dc supply from my big (80Ah,12v)battery.But the wire had to be taken to my upper floor and it seems the wire shares some pipes with the AC wires of the house.

I know this is not advisable.

But now ,whenever any switch that is sharing the pipes is flicked ,my circuit gets interrupted.

I am thinking that the change in current in the AC wires are inducing a signal in my DC.(But I have no way to verify and it is only a guess)

I tried hooking up a couple of capacitors but i didn't help.

If there is no other way ,I was thinking of connecting a smaller 12v battery in parallel near the circuit.Would this work?

Is there any other way?

2. kammenos Active Member

Aug 3, 2008
127
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Your circuit needs 12V? If so, you may have problems with voltage drop across the wire itself. Measure to be sure.

I believe that capacitors would do the work prety fine.. Maybe is the voltage drop your problem.

May 1, 2009
25
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no,i'm using a 7805 to get 5v output.
I'm suspecting that the ac is inducing an ac signal,like a negetive spike or something which is causing the problem

I have already tried 1000μF,10μF (3 in parallel too)and 0.1μF.
But the problem still persists.

I dont know the reason for the problem and dont know any way to find it out.
Any help would be appreciated

4. kammenos Active Member

Aug 3, 2008
127
0
try a box connection. As your line comes, a 1000uF cap across the (+) and (-), then a resistors in series and again a cap 1000uF... The resistor should be as high as possible, but low enough to be able to power your circuit with enough current. Use the ohms low for your calculation. If this does not work, i'm sorry, i cannot help you more...

>----|----\/\/\/\/-----|------> To LM
.......|.......................|
......==.....................==
.......|.......................|
.......|.......................|
>----|----------------|------>gnd

( ignore the dots. Used only for spacing)

May 1, 2009
25
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i have tried it but with a 10μF caps and 100Ω resistor
will try with higher values

6. R!f@@ AAC Fanatic!

Apr 2, 2009
9,664
1,110
Did u try using varistors and may be a 50Hz Inductor too

Rifaa

May 28, 2009
495
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If you're getting signal induction, try an RFC as well.

May 1, 2009
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will give the inductor a try
Sorry for the foolish question, but what is an RFC?

9. beenthere Retired Moderator

Apr 20, 2004
15,815
293
That is a radio frequency choke, or hash filter. I've got three in a drawer, but don't know who might carry them anymore. Maybe an auto sound system dealer.

May 1, 2009
25
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well ,sorry again for the silly question
what does an RFC look like,can i make one?what does it do?

11. DC_Kid AAC Fanatic!

Feb 25, 2008
764
16
muRata makes many RFC's