[vdr] Re: Cooling HDs in a VDR system - HD sleep modes

[Bernd Felsche <bernie@innovative.iinet.net.au>]

On Wed, Mar 26, 2003 at 11:53:43AM +0100, Jörg Knitter wrote:

> Additionally, the Barracuda is only 'active' for a maximum time of 4
> hours for recording or playback, but as I also use (like most of you) a
> desktop case, there is not really much free room for air.

> Do you have any experiences on this?
> (How) do you cool your hard disks?

I built a small analogue circuit based on a 555 timer and NTC
thermistor to provide a temperature-dependent duty cycle. When
"idle", the fan gets about 6 or 7 volts average and is very quiet.
When the thermistor reaches about 50 degrees, it's going full-blast.
Well, in theory... the 555 is good enough to sink the current, but
the volt-drop is a killer.

I had all the bits in the parts box when the whim struck me.

One of my "some day" projects is a small, digital fan controller
that's monitored and set through a serial port, operating up to 8
fans independently and sensing at 6 different points in the case.

It'd make a very good control system project for an under-graduate
engineer... but I graduated 20 years ago.

> Are there any circuits around that turn on a HD fan when a HD wakes up
> from standby mode or temperature sensors that control the fan?
> Any further experiences concerning drop outs on recordings if a sleeping
> HD (in my case the boot HD) in the system is being woken up while
> recording?

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