ASIair Plus voltage outputs.

andrew_l

I have been putting my new ASIair Plus through its paces and have found an odd anomaly with the four voltage outputs.

Firstly, the outputs are incredibly unwilling to be either switched on when off, or off when on. For example when I slide each slider across from Off position it turns green, and then as soon as I take my finger off the iPad screen it switches back to the Off position. In the end I managed to turn them all On, but now they are similarly resistant to being turned off.

Secondly, I have noticed some odd things about the voltages measured. There’s a small discrepancy between the voltage displayed on Outputs 1, 2 & 3 i.e. 11.8V displayed and 12.03V measured. OK. No huge problem there. But on Output 4 I see 0.4V displayed and 12.03V measured - as per screen shot below.

Thirdly when choosing Dew Heater I measure 12.03V at 100% output and 10.9V at 5% output, and values in between at intermediate outputs.

I should add that the ASIair does power my ASI2600 camera and two dew heaters alright.

Is what I’m seeing here consistent with what others see with their ASIair Plus?

w7ay

andrew_l Thirdly when choosing Dew Heater I measure 12.03V at 100% output and 10.9V at 5% output, and values in between at intermediate outputs.

(1) Be really careful how you use those ports. Those DC outputs are NOT DC outputs, but PWM (pulse width modulated) outputs. It is dangerous to power any sensitive devices from those ports. Shame on ZWO for not disclosing that in their specs.

(2) you can really only measure PWM output with a slow averaging RMS meter. If your meter reads peak voltage, you would always see 12V (or whatever the max voltage is) no matter how much you PWM. If the meter is not specified as peak or RMS reading, the meter can measure anything in between 0 and 12V.

(3) if you have long cables (i.e., inductive), the voltage from a PWM output can overshoot to way more than 12V. Again, be careful.

(4) best to use an oscilloscope rather than a meter to look at what you are really getting from those outputs. But best of all do not use those outputs at all except to power resistive loads such as dew heaters, and using as short a cable as possible in between.

Chen

andrew_l

Thanks, Chen, for your comments. I will bear those in mind. As for the stickiness of the sliders for toggling output voltages on and off, the supplier suggested this might be down to screen sensitivity. I certainly see less of a problem using my iPhone in place of my iPad. So, maybe that confirms that hypothesis. Anyway, once they’re set, they’re set which is what matters, right?

w7ay

andrew_l Anyway, once they’re set, they’re set which is what matters, right?

As long as you are not using one of those DC outlets from the ASIAIR to power anything other than dew heaters.

Chen

andrew_l

The problems I reported last year no longer occurred after recent updates.