Yet another question on external power supply for ISY

[Illusion]

If I have an external power supply, and I can choose my voltage, is their any compelling reason to choose one voltage over another?

 

I have an adapter that can do 5, 6, 7.5, 9, and 12V. In my world, higher voltage is generally better due to reduced amperage need. Is that the case here. 12V seems like a nice mid-ground from the 5-30V rating of the ISY; whereas, the 5V selection is right at the minimum of the range, so it would seem to me that if there were any issues with the adapter... being a little further away from the minimum would be good.

 

Thoughts?

[Brian H]

I would think 12 volts would be fine.

The original 2412S PLM that also provided DC to the ISY99i. Has a unregulated DC and was closer to 17 or 18 volts DC.

[apostolakisl]

I have my ISY powered off of a set of terminal blocks hooked up to an ATX power supply. Along with the ISY it is powering about a dozen other items both 12 and 5v.

 

It has been rock solid at the 5v. However, ATX power supplies produce a high quality, stable, clean 5v through a wide range of current draws.

 

Generally speaking (and I can't say for sure with ISY), electronics like this when presented with power above their need, dump the excess to heat via a voltage regulator. I have not opened my ISY to see what is in there, but you will recognize it if it is there as a chip with 3 leads, often mounted vertically with a heat sink attached usually right near where power enters.

 

So, in short, providing more than the minimal voltage will probably result in more heat. Heat is generally bad. However, if your 5v power supply is flaky, it would be better to over volt it a bit and let the ISY clean it up and bring it down to 5v.

 

So, there is my opinion.

[Illusion]

The power supply is rock solid. I had not considered excess voltage bleed off as heat by the ISY. I had assumed it would just use less amperage to function. If excess voltage is converted to heat to provide 5V internally in the ISY 5V would be the smart choice here.

[apostolakisl]

The power supply is rock solid. I had not considered excess voltage bleed off as heat by the ISY. I had assumed it would just use less amperage to function. If excess voltage is converted to heat to provide 5V internally in the ISY 5V would be the smart choice here.

 

Assuming it isn't the end of the world if your ISY gets flaky on you, I would try it at 5v. If it starts needing reboots, then you can move up the voltage. But if your 5v supply is nice, you shouldn't have any troubles. I certainly have not.