I was just wondering if anyone knew if there was a name for a component matching this description.

Positive terminal A with its ground (this being the power supply, probably 3-5V)
And then another positive terminal (B) with its ground connection.
There is a continuous 12V (or 5V) going to B, but isn't a completed circuit. However when power is supplied to A then it bridges the connection between terminal B & it's ground.

If it would be of any help, I could create a digital diagram, I apologise for my poor descriptive skills.
Thanks

 

I was just wondering if anyone knew if there was a name for a component matching this description.

Positive terminal A with its ground (this being the power supply, probably 3-5V)
And then another positive terminal (B) with its ground connection.
There is a continuous 12V (or 5V) going to B, but isn't a completed circuit. However when power is supplied to A then it bridges the connection between terminal B & it's ground.

If it would be of any help, I could create a digital diagram, I apologise for my poor descriptive skills.
Thanks

Yes, draw something out, take a photo with your phone and post it. Easy and makes things clear in a hurry.

 

Could be a simple NPN transistor or N-channel MOSFET, but you forgot to mention 17 things, like how many pins the device has, and does it look like a solid state component, or assembly, or or or..

ak

 

Digital transistor? See: http://www.infineon.com/cms/en/search.html#!term=digital#32transitor&view=all

 

Take a picture of it...

 

Yes, draw something out, take a photo with your phone and post it. Easy and makes things clear in a hurry.

 

I drew this up on my pone, do I need to include more detail or is this enough to identify the name of what I'm thinking of?
When power is supplied to the 5V DC, the 3.3V DC indicator should come on

 

I drew this up on my pone, do I need to include more detail or is this enough to identify the name of what I'm thinking of?
When power is supplied to the 5V DC, the 3.3V DC indicator should come on

It could be a wide range of transistors or gates. Are you looking for ideas or de-engineering something that already exists?
What kind of indicator?
Input current?
Output current?
Power consumption?
What kind of driving input circuit?

"Powered by 3.3 Volts" suggests a logic family. Something more than just a single transistor.
"1.3 Volts out" suggests a current limiting resistor on the output. Current limiting, maybe.
"2 Volts across the indicator" suggests a red LED maybe. Atypical LED, maybe 5 mA to 20 mA out current.
Single circuit? 74LVC1G07? 3.3 V logic family, 5 V tolerant input. OC driver out with a 150 ohm resistor on the output?
http://www.ti.com/product/SN74LVC1G...9ae9e9c97f09&gclid=COGtpu2o_c4CFYE6gQodOlgDOQ

 

That schematic does not describe the workings of the circuit itself, it does not seem to have any means of input, just output.
Max.

 

A problem with your schematic is that it shows the indicator permanently connected to the +3.3V supply and GND (so it is on al the time), and the device shorting the +3.3V supply to GND (so it goes boom). I assume what you really want is for the device to switch the +3.3V *to* the indicator. As such, it could be a solid state relay, an optocoupler, or a simple transistor. A lot depends on this:

Is it ok to connect the 5 V GND and the 3.3 V GND, or must the two GNDs remain isolated?

ak