Multisim and Ultiboard

cancel
Showing results for 
Search instead for 
Did you mean: 

voltage regulators

I had a PCB board built and assembled and the voltage regulator was put in backwards  the 5 volts regulator was installed backwards , putting the power source on the out put  instead of the input,  instead of dropping 15 volts to 5 volts,  the board have burnt up traces   and fried parts in all the circuits that was connected to that 5 volts rail ..

 

I decided to simulate the mistake in multisim and discovered a monster it stepped up the voltage and putout 49.965 KV...

With a 8 volts  supply , the monster put out 10 KV into a 100 ohm load

With a 15 volts  supply , the monster put out 36 KV into a 100 ohm load

With a 15 volts  supply , the monster put out 1.269  KV into a 1 ohm load

With a 40 volts  supply , the monster put out 4.547  KV into a 1 ohm load

With a 40 volts  supply , the monster put out 168  KV into a 1000 ohm load....

 

I know the monster is real because it fried the PCB and all the parts and burnt up the traces ,and would like some feed back from the community as to why ? and wan other members to experiment with the monster that was discovered ..

I added a buffer output transistor  to the monster and the monster grew bigger , can any one do a switch mode power supply ?

 

Can any one say if this is a multisim fanticy ? I also did an AC version

 

Thanks in advance

 

Download All
0 Kudos
Message 1 of 3
(3,888 Views)

Hello dubmaster

 

I am wondering about the configuration you are using because I saw you are connecting the COM (Voltage Controller) and the way you are connecting that is interesting.

I was studying the datasheet and in the Typical Applications page 21. I have not seen something similar. See below the datasheet I attached.

 

http://pdf1.alldatasheet.com/datasheet-pdf/view/82833/FAIRCHILD/LM7805.html

 

regards

0 Kudos
Message 2 of 3
(3,861 Views)

All I know It fried the board

0 Kudos
Message 3 of 3
(3,791 Views)