Multi-voltage Power Adaptor has large voltage output discrepency

[canidoit]

I have this power adaptor with selectable voltage from 3, 6, 7.5, 9, 12 and I decided to measure it and the voltage from the adaptor is off by alot and seems to behave weird.
3v = 12v
7.5v = 10v
12v = 16v

Similar to this.

For example first time I plugged it in, it was set at 9v but it was giving out 12v on the multimeter.

Then I turned it off and then changed the settings to other voltage values and it would sometimes stay at 12v for all the values.

Does the power adaptor store electricity on the-same voltage and I have to give it some time to reset and go to the new voltage?

Is it normal for these power adaptors to have readings that are way off, like 3v = 6v, 7.5v =12v, 12v = 16v?

I measured my other multi-voltage power adaptors and they behave the-same.

Thanks.

 

[Rob Flinn]

Did you measure the voltages with no load on the PSU ? i.e it is not powering anything when you measure it. If so the behaviour you are experiencing is to be expected.

 

[canidoit]

Hi Rob,

I just put the multi-meter pointers at the end of the plug. How do I measure it so that I can get the correct voltage from the power adaptor?

Also, isn't it the-same for audio? I mean I was doing some calibration on a compressor, and the instructions asked me to measure the XLR and get 1.23v for 0 VU. The XLR does not have a load though, I just measure it from the XLR out of the 500 series chassis?

Thank you.

 

[Rob Flinn]

Hi Rob,

I just put the multi-meter pointers at the end of the plug. How do I measure it so that I can get the correct voltage from the power adaptor?

Just plug the PSU into something so that you are powering, for example, a guitar effects pedal, & measure the voltage the PSU is putting out when it is powering the pedal. The more current you are drawing from the PSU the more the voltage will sag.

Also, isn't it the-same for audio? I mean I was doing some calibration on a compressor, and the instructions asked me to measure the XLR and get 1.23v for 0 VU. The XLR does not have a load though, I just measure it from the XLR out of the 500 series chassis?

Thank you.

Not quite the same because you are not drawing power. The output of the compressor is low impedance & you would normally be plugging it into maybe an upwards of 10k input impedance. Therefore there is little load on the output of the compressor & hardly any power transfer.

 

[canidoit]

Ok, thanks Rob!