Transformer Less Power Supply

Complicated circuits like computer, television etc needs dedicated power supplies , a small variation could destroy the whole system. But other devices like LED light, Alarm, Calling bell don't need specific, some variation cause no problem to the system.

BUT 110v, 220v or 240V mains voltage definitely kill any circuit if directly connected to it. The is an smps inside each device to chop the mains voltage like inside a computer all components run in 12VDC, inside a television 110VDC is the average power need for proper working. LED, LCD all need less than 12 Volt for proper working.

Here come the use of TRANSFORMER LESS POWER SUPPLY.











The above circuit is simplest of them all. Just 4 components to reduce mains voltage (VA) !!!!

The Capacitor 105J400 or 0.1uf 400v & 300K resistor is helping reducing voltages, Capacitor act like a pump, 0.1uf (micro farad) very smallest value, according to capacitor value it can only allow a small current across it, there is no loss of energy happening here, not even heating of components,

The 2 contacts inside capacitor is very long and they are not connected each other,  they are placed so close together so that AC (electrons) can jump either side. 0.1uf or 105J can block 99% of main voltage effectively. Only 1% is passing on.

The Main misunderstanding about AC is..  AC or alternating current act like a spring. The voltage is not fixed to 110v or 230 v , it may vary from 0 to 1KV or several KV's , on a split of a second. People don't give importance to the surge voltage, But in case of Capacitive Power Supply its an important factor. The output vary according to input.

* High current devices should not be operated in capacitive power supply. In parallel or series to the main line. If so, the voltage vary and output filter capacitor may explode, and kill whole device.


Transformer Less Power Supply effectively used on:

1. Chinese Rechargeble Torch Light
2. Rechargeable Table Fan, Table light
3. Toy Cars
4. Remote controls 
5. Voltage Testers
6. No Contact Testers.
7. Single Contact testers
8. LED Bulb etc.

 some varients of same design seen in above said applications.





The whole idea of capacitor power supply is  its very cheap, its not bulky, and weight few grams.


THE DISADVANTAGE

• No Isolation form mains voltage (VA) , person would get shock if he touch any contacts.
• No voltage regulation: voltage may vary