hi all again
would this triac work on 12v ?
i,m modding a sound to light to 12v dc from 230v ac
BT138 - 600E


http://www.digikey.co.uk/product-de...pc&WT.mc_id=IQ61350325-VQ6-24510235706-VQ16-c

 

It's rated for 600 volts maximum so I believe it will work with 12 volts.

 

I don't think a triac will work on DC.
If I remember correctly it needs the volts across it to go to zero before it can switch off.
But, I could be wrong.

 

could i use a tip120 if i get the Vces to 2V ?

 

nigel is wright, but you aren't telling us the circuit. There is nothing here except guessing if you don't tell what circuit you are trying to make.

 

i will photo circuit and add components to the image this weekend thanks any way
marko

 

uploaded photo's for you all to see
thanks
marko

 

Again, nigel is wright. You can't use triacs to supply DC because they will never turn off. Your circuit depends on the polarity change of the AC power to shut down after each "on" event.

A TIP120 is a Darlington, so it has a chance of working with a 12V DC supply, but you will have to redesign the circuit to make sure it will work.

 

ok
so if i keep this circuit the same could i add a bank of 4 other transistors side by side to the existing outputs but just use a + or - v 12v supply to them ?
what i am trying to achieve is to replace the 230v bulbs with 12v led's

 

if i keep this circuit the same could i add a bank of 4 other transistors side by side to the existing outputs but just use a + or - v 12v supply to them ?
what i am trying to achieve is to replace the 230v bulbs with 12v led's

Start by making a schematic of the board then redesign it to use 12 volts.

 

If there is an AC source to the items (lights?) you want control (transformer secondary?) and it is via a bridge rectifier, put the Triac before the bridge!.
IOW in the AC side of the rectifier.
Max.