3 A typical installation involves attaching
4 only a suitable battery, a single pole switch for
5 power on/off, and two pairs of wires connecting e-matches for the
6 apogee and main ejection charges. All Altus Metrum products are
7 designed for use with single-cell batteries with 3.7 volts
9 EasyMini may also be used with other
10 batteries as long as they supply between 4 and 12 volts.
12 The battery connectors are a standard 2-pin JST connector; you
13 can purchase suitable batteries from the any vendor selling
14 Altus Metrum products. These batteries are
15 single-cell Lithium Polymer batteries that nominally provide 3.7
16 volts. Other vendors sell similar batteries for RC aircraft
17 using mating connectors, however the polarity for those is
18 generally reversed from the batteries used by Altus Metrum
19 products. In particular, the Tenergy batteries supplied for use
20 in Featherweight flight computers are not compatible with Altus
21 Metrum flight computers or battery chargers.
24 Check polarity and voltage before connecting any battery not
25 purchased from Altus Metrum.
28 Spark Fun sells batteries that have a matching connector with
29 the correct polarity. However, these batteries include an
30 integrated current limiting circuit. That circuit will cause
31 the battery to shut down when firing the igniter circuit. Do
32 not use these batteries unless you remove the current limiting
35 By default, we use the unregulated output of the battery
36 directly to fire ejection charges. This works marvelously
37 with standard low-current e-matches like the J-Tek from MJG
38 Technologies, and with Quest Q2G2 igniters. However, if you
39 want or need to use a separate pyro battery, check out
40 <<_using_a_separate_pyro_battery>> for instructions on how to wire
41 that up. The altimeters are designed to work with an external
42 pyro battery of no more than 15 volts.
44 Ejection charges are wired directly to the screw terminal block
45 at the aft end of the altimeter. You'll need a very small straight
46 blade screwdriver for these screws, such as you might find in a
47 jeweler's screwdriver set.
49 The screw terminal block is also used for the power switch leads.
53 Except for TeleMini v1.0, the flight computers also use the
54 screw terminal block for the power switch leads. On TeleMini v1.0,
55 the power switch leads are soldered directly to the board and
56 can be connected directly to a switch.
60 For most air-frames, the integrated antennas are more than
61 adequate. However, if you are installing in a carbon-fiber or
62 metal electronics bay which is opaque to RF signals, you may need to
63 use off-board external antennas instead. In this case, you can
64 replace the stock UHF antenna wire with an edge-launched SMA connector,
65 and, on TeleMetrum v1, you can unplug the integrated GPS
66 antenna and select an appropriate off-board GPS antenna with
67 cable terminating in a U.FL connector.