Power consumption of the Sony TCD-D8

From: Hornstein <
U.Hornstein@t-online.de>
Subject: Power consumption of the Sony TCD-D8
Date: Fri, 15 Mar 96 15:39 +0100 and Tue, 19 Mar 96 17:29 +0100

Hi Dat-heads,

finally I got myself a Sony TCD-D8. Thanks from here to all who
gave me their advice on DAT-portables.

Power consumption of the TCD-D8
===============================
In the digest were several opinions upon the power consumption of
the D8. To give these opinions a more solid basis, I did measure
the current (DC), taken from an external 6.0 Volt stabilized power
supply, connected to the battery terminals of the D8, D8 operating
in battery mode:

D8 Status   Hdphn OFF   Hdphn ON
=====================================
Off         0.35 mA     0.42 mA   (!)
Stop        170 mA      210 mA
Rec         180 mA      220 mA
Play        190 mA      230 mA
Rec+Play    200 mA      240 mA
>>, <<      230 mA      270 mA

Light       additional  12-15 mA

Notes:
"Hdphn ON" means, a plug is inserted into the headphone/line out
jack, with little or no effect
        1) of the adjusted volume or
        2) the load resistance of the headphones or
        3) the position of the phones/line switch.

The inserted plug activates the entire output circuitry,
which takes approx. 40 mA, regardless of the current
flowing out of the jack (I did not test extremes).


To get most out of your batteries:
==================================
---> Insert a headphone/Line out plug only when needed.
---> Switch OFF the D8 with "Stop, Hold" when done, instead of
        waiting for the timed-out off.
---> Use the light briefly.
---> Use the power supply whenever possible.      :-)



The built-in battery meter
==========================
For those interested I also measured the boundary voltages of the
battery-meter. These voltages are only rough measures; the
circuitry seems to take the time-dependancy of the battery voltage
drop into account.

E                                  F
=== ========== ========== ==========
=== ========== ========== ==========
4.7 4.8----4.9 5.0----5.2 5.2----6.0    Volt
                                 +up
Below 4.7 V the display blinks with "battery", below 4.6 V the D8
goes into Sleep Mode (off).

Some folks commented my measurements (thank you).
I won't repeat all comments here, but David Brown was right when
he wrote on March 17:

>I think what he's [thats me, uh] referring to is the time lag in
>the battery indication. I did the same measurements on my D7 and
>it takes a while for the indicator to register a change in
>voltage.

One reason for the time lag is a 470 uF Capacitor parallel to the
battery poles. But IMO there must be an additional logic in the
circuitry of battery segment lighting. For example, if I increase
the voltage again after a period of drop, the segments do not
react correspondingly, as they would if they would be doing plain
comparison with fixed (time-invariable) voltages.
All these make the measurements unsafe.

Happy DATing,
with greetings from Freiburg, Germany

Ulrich Hornstein

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