John -- some suggestions
I doubt LED's will be bright enough on a sunny day to work well;
an incandescent lamp, especially flashing, would be better. Best
would be an aural alarm, but your choice of the fuel pump or the
strobe to trigger the alarm necessitates a way of temporarily
killing the alarm. Best would be an arrangement which senses
95% of throttle application, so the circuit is active only when
you're taking off. Another option is an oil pressure switch.
I don't think you need any logic chips. If you use microswitches
that open when the shoot bolt comes thru the hole in the door frame,
then just wire them in parallel, and this is the ground of your circuit.
Diode-isolate any multiple, positive inputs, and you have a circuit
to power any alarm within the current capacity of everything.
If you want an aural alrm with enough decibels to overide headphones,
you may need a power transistor or relay; or, an audio oscillator that
feeds the aux audio input of the comm radio.
Regards,
Fred Fillinger, AO63
On 9/18, you wrote --
>I am considering powering the "door unlatched" warning annunciator through
>diodes so that it is enabled if either the fuel pump OR the strobe light has
>power applied AND either door is unlatched. This should ensure that the
>warning is active prior to takeoff while avoiding annoyance on the ground.
Is
>this reasonable? And given this arrangement, would it be wise to add a
>warning horn also?
>My annunciator LEDs are on a small perf board to be mounted on the horizontal
>section above the gear handle; the LEDs are in a line above this handle so
>that they mount directly on the perf board. Has anyone used CMOS logic
>mounted on a board like this within the panel but without a metal case? I
>have some ideas for simple logic circuits to drive annunciators but don't
want
>to get bogged down with problems due to RF pickup.
> John A044 Newtown, CT
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