Eggtimer Rocketry Eggtimer User Manual page 12

The downside of breakwires is that it's one more thing you have to set up on the pad. See
Appendix D for airstart and breakwire implementation tips.
Indicator Pads – .1"-spaced pads with outputs for the following external indicators:
Ready LED – In parallel with the on-board Ready LED.
BUZ – In parallel with the on-board buzzer. This must be a pizo element.
ALED – Channel A continuity LED (polarized, +/-)
BLED – Channel B continuity LED (polarized, +/-)
Ready LED (RDY, +/-)
This is an external extension of the on-board RDY (yellow) LED.
The READY LED on the Eggtimer is used to indicate that either the Eggtimer is in flight mode
(solid ON), the flight is complete (ON with the IND LED also ON), or is ready for download
(flashing ON). It also flashes along with the buzzer to indicate peak altitude after the flight, and
flashes with the IND light after programming to let you know that the Eggtimer is halted. You
can connect an external LED to the READY terminals so that you can visually confirm that the
Eggtimer is ready for flight to begin or has completed. You will need an LED capable of
lighting with approximately 10 ma of current or less, most medium-to-high intensity LEDs will
work fine. The "long" lead of the LED should be connected to the "+" terminal, the shorter one
should be connected to the "-" terminal. If you are using an external LED in a holder with leads,
the red wire should be connected to the "+" terminal and the black wire should be connected to
the "-" terminal.
We recommend using an "ultra bright" LED, they are easier to see outdoors but they will draw
more current. The reality is that the amount of time that the Ready LED is going to be on is very
small, and any decent battery is going to run a long time without worrying about an extra 10 ma
of current draw for a few minutes.
BUZ – Buzzer
This is an extension of the on-board pizo buzzer. The on-board buzzer isn't meant to be very
loud, it's designed to be used as an indicator when you're right next to the Eggtimer to tell you
that it's ready, or to beep out the altitude after the flight. If you want to add a louder one, you
can use these terminals. The buzzer may be a pizo electric element, or it can be a pizo buzzer
with a built-in driver. It must draw less than 20 mA.
If you want to add a VERY LOUD buzzer that helps you find your rocket, and you have a
deployment channel available, you can use the unused deployment channel in continuous mode
with a 9v-12v battery and a Mallory Sonalert® buzzer. They're about $10. If you're not using
CHB, just put it in drogue mode (option 1) and change the On-Time to be zero; if you're not
using CHA, put it in Main deployment mode (option 1), choose a low deployment altitude,
maybe 200' or so, and set the On-Time to zero. You can also use the AUX3 channel with a
- 12 -