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Hi All,
I’m adding some accessories to my telescope for Astrophotography, and want to repurpose one of my old AC-DC adaptors for my autofocuser, as it didn’t come with a power supply. It requires 12V 0.5A input. So I went through my old box of adaptors collect from various old telephones, routers, modems etc. Below is a picture of several that have labels saying they output in the 12V 0.5-1.0 amp range.
The one on the left doesn’t show the output polarity, so I put my multimeter on it, but the readout just flickered between 0.1v and 0.2v. So just to make sure I was testing correctly, I started testing the other adaptors, and this is where my question arises.
After I went through and tested all the others, they ended up showing voltage outputs at the jack of between 15.6V and 20.V!!
So my question is, is this normal to get output voltage from a 12V adaptor, that is much higher than 12 volts? Is it an artefact of only using a multimeter to test, and real world usage would not show this high a voltage, or what? I always assumed these were regulated outputs and you could rely on a label saying 12V output, to be pretty close to 12V. Surely having 20V output would fry some things if they were expecting 12V.
My particular use-case, the focuser, I’m informed by the manufacture should accept from 12V-15V. None of these adaptors were below 15V, although one was close. So would none of these be acceptable to use?
Thanks. Russell.
Hi All,
I’m adding some accessories to my telescope for Astrophotography, and want to repurpose one of my old AC-DC adaptors for my autofocuser, as it didn’t come with a power supply. It requires 12V 0.5A input. So I went through my old box of adaptors collect from various old telephones, routers, modems etc. Below is a picture of several that have labels saying they output in the 12V 0.5-1.0 amp range.
The one on the left doesn’t show the output polarity, so I put my multimeter on it, but the readout just flickered between 0.1v and 0.2v. So just to make sure I was testing correctly, I started testing the other adaptors, and this is where my question arises.
After I went through and tested all the others, they ended up showing voltage outputs at the jack of between 15.6V and 20.V!!
So my question is, is this normal to get output voltage from a 12V adaptor, that is much higher than 12 volts? Is it an artefact of only using a multimeter to test, and real world usage would not show this high a voltage, or what? I always assumed these were regulated outputs and you could rely on a label saying 12V output, to be pretty close to 12V. Surely having 20V output would fry some things if they were expecting 12V.
My particular use-case, the focuser, I’m informed by the manufacture should accept from 12V-15V. None of these adaptors were below 15V, although one was close. So would none of these be acceptable to use?
Thanks. Russell.