Is there any method to identify if the input to this transformer can be supplied with 220V? I had salvaged this circuit board and two 6V 12Ah SLAs in parallel from a Teledyne Big Beam 25W old emergency lamp. Someone had dropped the lamp and the bulbs where damaged but the circuit was working fine and battery was dead so rejuvinated it and maybe I could use it to charge my other 6V SLAs. The charging circuit is pretty old and can be easily understood by looking at the circuit board. ITs got a simple full bridge rectifier and some kind of transistor and a relay to power the lamp during failure. Usually emergency lamps run on both 110V/220V but this one is made in USA and has that 110V plug. Also anyone has any idea what is the transistor for. It seems to be generating a lot of heat and its connected to a big aluminium plate tha maked the circuit enclosure.

 

The transformer could possibly be dual primary for 120/240 a resistance check may confirm it.
Max.

 

The transformer could possibly be dual primary for 120/240 a resistance check may confirm it.
Max.

Higher resistance is 220V right?

 

But ususally emergency lamp circuits are dual and have not voltage selector, then how does it choose if I plug to a 110 or 220V outlet?

 

Its probably a 230V using a Lm7806 regulator, or power transistor and zener, so gives out 6V dc so it will work just as good on 110V, otherwise its the relay that is detecting the 230V.

 

But ususally emergency lamp circuits are dual and have not voltage selector, then how does it choose if I plug to a 110 or 220V outlet?

Maybe hard wired at construction time.
Max.

 

Its probably a 230V using a Lm7806 regulator, or power transistor and zener, so gives out 6V dc so it will work just as good on 110V, otherwise its the relay that is detecting the 230V.

I just wanted to be sure because few years back accidently plugged a 30V 1A 110V input transformer into a 220V outlet and it was KABOOM!! in 5 secs and a fire.

 

Maybe hard wired at construction time.
Max.

I checked and the transformer has two red output wires to 4 big diodes and 2 nitro 35 V 470uF caps and the input is a pair of two wires (white and black). the relay is for detecting if the input power is cut and it powers the lamp.

 

Well follow the mains input wires, and see what its wired to....or post better pictures of the mains supply.

 

Well follow the mains input wires, and see what its wired to....or post better pictures of the mains supply.

I checked just now and the two input wired go through a relay to the transformer. Relay is activated when connected to the mains to prevent the light from working while connected. The transformer has only two input wires a white and black wire.

 

Sounds like the W & B are just 120v only if US origin.
Max.

 

Sounds like the W & B are just 120v only if US origin.
Max.

Unfortunately I couldnt find any datasheet when I tried searching the seriel no. on the transformer. But the "State Of Charge " gauge shown in above pic is a modutek and has the label made in USA tag. Thats the main reason why I tried it only with 110Volts.