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
15,819
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.
 

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.
 

Norfindel

Joined Mar 6, 2008
326
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
22,230
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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