None of the recorders were behaving at all like CC sources, at least
with loads drawing anywhere around .5mA. They behaved much more like
The current was pretty linear with the load, more like an ordinary
voltage supply with a resistor in series.
I just measured the PiP current supplied into a dead short for each
recorders. That's the maximum current that they can deliver. Here's
a revised table showing that as the last column:
MODEL V (unloaded) V @ 0.50 mA Load (Ohms) mA @ 0
Ohms
=3D
=3D
=3D
=3D
=3D
=3D
=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Sony D50 2.82 0.52 1030 0.61
Zoom H4n 2.84 1.82 3606 1.38
Olympus LS10 3.02 1.93 3828 1.40
Nagra ARES-MII 2.81 1.78 3580 1.37
This suggests that the H4n, LS10, and ARES-MII use an internal series
resistance of about 2.2K Ohms, while the D50 uses about 4.7K Ohms,
with each having a roughly 3V voltage source.
-matt
On Aug 21, 2009, at 21:54, umashankar wrote:
> somewhere i remember reading that many new plug in power sources are
> constant current, which of course changes the way we measure. it
> should be possible to identify the constant current sources quite
> easily.
>
> it would make sense to provide constant current rather than voltage
> when working with very low voltages.
>
> umashankar
> i have published my poems. you can read (or buy) at http://stores.lulu.c=
om/umashankar
>
>
>
>
> ________________________________
> From: Klas Strandberg <>
> To:
> Sent: Saturday, August 22, 2009 7:12:29 AM
> Subject: Re: [Nature Recordists] Plug in power voltage?
>
> Great Matt! Thank you!
>
> This needs some consideration.
>
> You have to load the Sony 3 times as much to squeeze the 0,5 mA out
> of it because the voltage drops..?
> Do you see any other interpretation?
>
> Klas.
>
>
>
> At 18:22 2009-08-21, you wrote:
>> On Aug 21, 2009, at 7:07, Klas Strandberg wrote:
>>
>>> Hi folks!
>>>
>>> It would help me and users if I better knew about the plug in power
>>> voltage that different recorders provide.
>>>
>>> This is the test:
>>>
>>> 1/ Connect a potentiometer and a mA meter in series between input
>>> and ground.
>>> 2/ Set the potentiometer so that the mA meter shows 0,5 mA.
>>> 3/ Measure the voltage between input and ground.
>>>
>>> For the moment I am specially interested in the voltage that Sony
>>> PCM-D50 provides at a given current, like 0,5 mA.
>>>
>>> Klas.
>>>
>>>
>>>
>>
>>
>> OK, I just did the LS-10, too: 1.93V
>>
>> To summarize (view in a monospace font):
>>
>> MODEL V (unloaded) V @ 0.50 mA Load (Ohms)
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> Sony D10 2.82 0.52 1030
>> Zoom H4n 2.84 1.82 3606
>> Olympus LS10 3.02 1.93 3828
>>
>>
>> So the Sony is an outlier here.
>>
>> Note that my 0.50 mA current adjustment was only approximate -- I set
>> the load resistor to get as close to 0.500 mA to flow as I could, but
>> really got only within +/- 1 % or so. So the loaded voltage isn't
>> exactly R * .0005, because the current wasn't exactly 0.5000 mA.
>> It's
>> just close. Ohm's law still applies in Philadelphia, in spite of
>> what
>> the numbers above might suggest!
>>
>> V measurements were done with a recently calibrated Fluke 189.
>> Current was measured with a Fluke 289, also recently calibrated.
>>
>> -matt
>>
>>
>> mab blogs at http://www.crypto.com/blog/
>>
mab blogs at http://www.crypto.com/blog/
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