Wrong Voltage on SMR-4


I just bought the Shruti last week and assembled it …
I just proceed to the power test and the voltage seems to be wrong :
input is 8.7 V and the measurment on the output of the 7905 and 7805 is still 8.7 V
it seems that the 7905/7805 are not regulating the power ???

I double check , but nothing seems wrong

Any idea ???
Many thanks

Have you checked for shorts on the pins of the 7805?


I think … I find it. It seems that the powerbox (old refurbish I have found) used was not working
With a decent stable power (10A) it works :slight_smile:
Do you think the powerbox must deliver suffisant Amp’s ?
What is your recommendation ?
Many thanks

500mA + if you want to drive the Shruthi + a Programmer :wink:

I have found a 300mA supply that fails to deliver more than 150mA, so even if the Shruthi requires about 180mA, I would recommend 500mA instead of 300mA :slight_smile:

500 mA DC I suppose ?
Is the polarity important ?

In fact I have tested 2 of these “old” power device (surely delivering 500mA) and there were not working …
Maybe you you can give me the reference of one I can buy on the net ?

Thanks !

inner pin must be positive

The one I give with the assembled units is Farnell #1217079