Approach Timer Frustration

Put a Garmin 430 or 530 in your airplane. They do the countdown timer
thing automatically for approaches and holds. And - they're only a
thousand times more expensive than the West Bend kitchen variety!

Dave Blevins

On 15 Jan 2004 09:44:35 -0800, (Andrew Sarangan)
wrote:

Over the years I have been using various digital timers, but so far I
have not been satisfied with any of them. The LCD displays make them
difficult to read when viewing at different angles. The right seat
pilot (or CFII) cannot see the digits. Lack of illumination in most
units is another big problem for night use. Size is another issue.
Most of the timers appear to be way too bulky for their function. For
example, the ASA timer is larger than any instrument in the cockpit.
If you install it on your yoke clip, it would cover up half of the
approach chart. For some reason, the manufacturers seem to be obsessed
with presenting large digit displays. That may be good for home or
outdoor use, but there is really no need for the digits to be 10
times larger than the font size on the approach charts.


For a long time I have been looking for a very small timer (1" x 1")
with an LED display (not LCD) that could be glued to the yoke clip.
With LED displays, battery life could be a problem, but one could
easily solve that by having an on/off switch (most timers seem to run
continuously regardless of use). Any ideas where I may find such a
device?

"Casey Wilson" wrote in message
...

"S Narayan" wrote in message
...
Got the Radio Shack count up/down timer which can be set easily. It is
big
though (2" or so on a side). I connected an external AAA battery and put
in
a red LED across the speaker. I can now see when the timer expires with
the
flashing LED since I doubt I could hear the speaker go off.


Can you provide a schematic? Please.


I don't have the timer with me now, but IIRC, I experimented by putting
several types of LEDs across the speaker inside, and it worked. In fact, the
speaker works while the LED flashes. I didn't care if the speaker died, so I
used the largest LED I had. I believe, there is some some kind of a
charge-pump type circuit which steps up the voltage to tens of volts to
drive the piezo type speaker. The somewhat high voltage won't hurt the LED,
since the speaker driver cannot provide much current. The whole timer used
to run off a 1.5V button cell. The standby current drain is around 5uA and
putting an external AAA battery will keep it going as long as the battery
manages to stay alive which may be a several years. The self discharge may
be higher than what the timer needs!

"S Narayan" wrote in message
...

I don't have the timer with me now, but IIRC, I experimented by putting
several types of LEDs across the speaker inside, and it worked. In fact,
the
speaker works while the LED flashes. I didn't care if the speaker died, so
I
used the largest LED I had. I believe, there is some some kind of a
charge-pump type circuit which steps up the voltage to tens of volts to
drive the piezo type speaker. The somewhat high voltage won't hurt the
LED,
since the speaker driver cannot provide much current. The whole timer used
to run off a 1.5V button cell. The standby current drain is around 5uA and
putting an external AAA battery will keep it going as long as the battery
manages to stay alive which may be a several years. The self discharge may
be higher than what the timer needs!

Okay, now I've got it. I was confused over what you did with the battery.
Now I see all you did was supplement the main unit battery -- it had nothing
directly to do with the LED which simply parallels the pizeo transducer.
Thanks.