I am using two AC to DC power supply one with 12V DC output and another 24 V DC Output. Each one is used to power different type of LEDs. In order to trigger the led the I have used transistor as switch and it is getting triggering signal from FPGA. Previously I had shorted the ground of 12V DC and 24 V DC output to GND of FPGA so triggering signal was working. Now I had to increase number of LEDs due to requirement . Now when I power on the system my ground wire between the 24v DC and 12 v DC got burned. After measuring the voltage difference there is -24 V difference between the ground of 12V DC output and 24 V DC output. When I remove the additional LED circuit there is no potential difference between ground.

Please suggest.

 

You should likely tie the grounds together..

But a complete schematic would help us answer better..

 

You should likely tie the grounds together..

But a complete schematic would help us answer better..

Thanks! One of transistor was blown and it made connection short !. thanks again

 

We really need a schematic of how you have things connected as well as what you are measuring where.