Getting power from 220VAC switch

Thread Starter

kammenos

Joined Aug 3, 2008
127
Hi there. I'm thinking of getting 5V power from the switch of a 220VAC, for dimmer and staff. I did some tests with a 10 Ohm resistor in series with the switch and got up to 6V. Bigger resistors gave me more voltage.

But the light was on....

The question:
How could i get the same voltage when the light is off
I do not want to use transformer as they are BIG to fit in a household switch case...
 

beenthere

Joined Apr 20, 2004
15,808
That is a very unsafe way to get power. The circuit will always present a lethal shock hazard. You are advised to use a wall transformer for safety.
 

mik3

Joined Feb 4, 2008
4,846
What do you want to power with the 5V?

Do you want 5V AC or DC?
 

eimix

Joined Sep 2, 2008
32
I suggest use PC power suply unit
for DC it is powerfull - 5v -> 12-20A, 12v -> 5-12A
 

Thread Starter

kammenos

Joined Aug 3, 2008
127
Maybe i said it wrong.

1. I do not want external power supply
2. I will power 200mA
3. I do not care for AC/DC. Whatever.
 

Thread Starter

kammenos

Joined Aug 3, 2008
127
What device will you power?
But is it THAT important? Some 555, some other chips, some resistors, some capacitors. A circuit that i am researching right now. No motors. But why is that so important?
 

Mike Mandaville

Joined May 27, 2009
81
But is it THAT important? Some 555, some other chips, some resistors, some capacitors. A circuit that i am researching right now. No motors. But why is that so important?
Is there some reason why you could not just use a nine-volt snap-on battery?
 

Norfindel

Joined Mar 6, 2008
325
But is it THAT important? Some 555, some other chips, some resistors, some capacitors. A circuit that i am researching right now. No motors. But why is that so important?
Because taking 5v from the 220v line will likely leave the *live* wire on your supposedly low-voltage circuit, potentially killing anyone who touches the live wire and ground at the same time. Not safe to work.
 

SgtWookie

Joined Jul 17, 2007
22,201
If you're going to be working with 555 timers and logic IC's, you will need regulated DC power.

An inexpensive (and safe) way to do this is to use a "wall-wart" type power supply with a voltage regulator on the output.

Look for a surplus "wall wart" supply that will put out 500mA to 1A at 8 to 12v. You can use a 7805 regulator with a large capacitor on the input and smaller caps on the output to provide decently regulated voltage for not much cost. A heatsink for the regulator is advisable.
 
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