8 channel io board power transistor hot

[ksdehoff]

Hey all:

I have a question on the 8 channel input board. I'm interfacing it to my security system which has the contacts all normally closed. This results in the relays being on pretty much all the time. I notice the transistor getting very hot to the touch (156 deg) and I'm wondering if this is expected (it does have a heatsink on it). Also if I were to power the hub externally would this reduce that heat at all?

Thanks
Ken

 

[ericvic]

Hey all:

I have a question on the 8 channel input board. I'm interfacing it to my security system which has the contacts all normally closed. This results in the relays being on pretty much all the time. I notice the transistor getting very hot to the touch (156 deg) and I'm wondering if this is expected (it does have a heatsink on it). Also if I were to power the hub externally would this reduce that heat at all?

Thanks
Ken

Ken,

The voltage regulator can get pretty hot if all the outputs are energized. If you are using the new version of the 8 Channel I/O board with the surface mount relays they have a normally closed position that you can use when the relay is not energized, it is marked NC on the board.

Eric