User`s manual

- 8 -
no user intervention or programming required. This is the same logic that has been proven in the
classic Eggtimer for hundreds, if not thousands, of flights.
Getting to know your Eggtimer TRS
Although the Eggtimer TRS seems relatively simple, you will want to familiarize yourself with it
BEFORE you install it in a rocket, and certainly before you try flying it.
There are several set of solder pads for making connections to the board, and some indicators.
BATT – Two solder pads, marked “+” and “-“, for connecting the Eggtimer battery. We
recommend using a 2S 7.4V LiPo battery, but any battery from 4.5v-20v can technically be used.
Average current draw with the GPS running is about 70 ma, but there may be peaks of about 200
ma for a short time while the GPS module acquires satellites.
DPWR – Two solder pads marked “+” and “-“ for connecting the deployment power battery.
You can use just about any battery from 3v-60v, the battery choice is dependent mostly on the
requirements of your deployment igniter. Most igniters work well with a 2S 7.4V LiPo, similar
to what we recommend for the main power. We strongly recommend that you use a switch in-
line with the “+” terminal of your battery to disable deployment power until your rocket is on the
rod/rail
MAIN - Two solder pads for connecting an electric match or other low-to-medium current
device. Deployment altitude is programmable, from 100-1,200 ft, or it may be disabled if not
used. Maximum 8A current, 60 VDC, 65 W.
DROG - Two solder pads for connecting an electric match or other low-to-medium current
device. This channel may be used for a “drogue” chute to slow down the computer at apogee, or
it may be disabled if not used. Maximum 8A current, 60 VDC, 65 W.
Data Port – 3-pin TTL-compatible header connector for connecting the USB-serial data cable
for programming and downloading data.
PWR – RED LED that comes on when power is connected to the computer side.
Buzzer - “Beeps” out status, warnings, altitude, and other important notifications.
1S – Amber LED that blinks once per second when the GPS has acquired enough satellites to get
a “good” fix. This will occur (usually) if it sees at least four satellites. See the section on “Using
the Eggtimer TRS with the Eggfinder LCD Receiver” for more details.