Tca785 gnd and thristor whith bridge rectifier diode

[ta2mix]

Hi this is siemens TCA785 datasheet picture. it use +15 -15 volt but where connect to GND and if I connect to the load rather than bridge diode, can I drive 4kw dc motor.
what can be problem

 

[ABHI9868715910]

Hi,

Please attach the picture of the circuit,you can see the ground at pin 1.

 

[KlausST]

Hi,

yes, funny I´d like to say this is a typical (siemens) schematic of the 70s.

MP is the ground from the mains side seen.
-15V is the ground from the circuit supply side seen.

And the real fun with this schematic is:
I´m very sure that "-15V" is the return path of the "+15V" and the voltage difference is only 15V (instead of the usual/mathematical 30V)

So maybe I´m wrong, but i´d say wipe out the "-15V" text and name it "GND".

Why do i think this:
On page1 you see the device.
Pin 1 is marked with "GND" ( in your given schematic this is marked with "-15V")
Pin16 is marked with "Vs" ( in your given schematic this is marked with "+15V", what makes sense)

On page4 you see the Vs specification that says: abs. max. limit = 18V --> 30V would kill the device...

***
In the past i had to work with this IC and also had trouble with the datasheet.
***

Hope this helps

Klaus

 

[KlausST]

Is the problem solved?

Klaus

Add:

just seen this is a very old thread.