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 ifdef::telemini[TeleMini v2.0 and]
10 EasyMini may also be used with other
11 batteries as long as they supply between 4 and 12 volts.
13 The battery connectors are a standard 2-pin JST connector; you
14 can purchase suitable batteries from the any vendor selling
15 Altus Metrum products. These batteries are
16 single-cell Lithium Polymer batteries that nominally provide 3.7
17 volts. Other vendors sell similar batteries for RC aircraft
18 using mating connectors, however the polarity for those is
19 generally reversed from the batteries used by Altus Metrum
20 products. In particular, the Tenergy batteries supplied for use
21 in Featherweight flight computers are not compatible with Altus
22 Metrum flight computers or battery chargers.
25 Check polarity and voltage before connecting any battery not
26 purchased from Altus Metrum.
29 Spark Fun sells batteries that have a matching connector with
30 the correct polarity. However, these batteries include an
31 integrated current limiting circuit. That circuit will cause
32 the battery to shut down when firing the igniter circuit. Do
33 not use these batteries unless you remove the current limiting
36 By default, we use the unregulated output of the battery
37 directly to fire ejection charges. This works marvelously
38 with standard low-current e-matches like the J-Tek from MJG
39 Technologies, and with Quest Q2G2 igniters. However, if you
40 want or need to use a separate pyro battery, check out
41 <<_using_a_separate_pyro_battery>> for instructions on how to wire
42 that up. The altimeters are designed to work with an external
43 pyro battery of no more than 15 volts.
45 Ejection charges are wired directly to the screw terminal block
46 at the aft end of the altimeter. You'll need a very small straight
47 blade screwdriver for these screws, such as you might find in a
48 jeweler's screwdriver set.
50 The screw terminal block is also used for the power switch leads.
54 Except for TeleMini v1.0, the flight computers also use the
55 screw terminal block for the power switch leads. On TeleMini v1.0,
56 the power switch leads are soldered directly to the board and
57 can be connected directly to a switch.
61 For most air-frames, the integrated antennas are more than
62 adequate. However, if you are installing in a carbon-fiber or
63 metal electronics bay which is opaque to RF signals, you may need to
64 use off-board external antennas instead. In this case, you can
65 replace the stock UHF antenna wire with an edge-launched SMA connector,
66 and, on TeleMetrum v1, you can unplug the integrated GPS
67 antenna and select an appropriate off-board GPS antenna with
68 cable terminating in a U.FL connector.