Remote powering on of Hypex amp

[surfstu]

My home automation system (Openhab) will be used to power ON my Hypex SMPS and UCD amp modules.

I'm using the digital out of an arduino based microcontroller (ESP8266) to switch the SMPS in and out of standby. I understand that the Hypex SMPS requires a voltage approx 3.5V - 12V to hold it in standby and when there is no voltage then the amp will be ON.

I will have a seperate (permantly on) supply for the ESP8266 of 5V.

My question to anyone who knows more then me (most of you) is whether it is better to switch this voltage with

- a simple NPN transistor and a resistor

- or a coil relay

- or a solid state relay

 

[Antana]

Hi,
Just use the transistor, that wil be fine.

 

[surfstu]

Thanks Antana,

I was about to email Hypex to discover the current requirements to hold the SMPS in standby.

The arduino can only deliver 12mA 5V so I think a transistor will be necessary?

Also, is it OK to run a transistor in this state (saturation) for long periods of time?

Stu

 

[Antana]

In the datasheet a formula is given to calculate the current, however, it is good practice to always use a transistor and not directly powering from a uC.

 

[surfstu]

Great, thanks for the reassurance.

And it is OK to drive a transistor in its ON state for - weeks - months - years?

S