87 lines
3.4 KiB
PHP
87 lines
3.4 KiB
PHP
== TeleMetrum
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.TeleMetrum v2 Board
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image::telemetrum-v2.0-th.jpg[width=400]
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.TeleMetrum v1 Board
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image::telemetrum-v1.1-thside.jpg[width=400]
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TeleMetrum is a 1 inch by 2¾ inch circuit board. It was designed to
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fit inside coupler for 29mm air-frame tubing, but using it in a tube that
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small in diameter may require some creativity in mounting and wiring
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to succeed! The presence of an accelerometer means TeleMetrum should
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be aligned along the flight axis of the airframe, and by default the ¼
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wave UHF wire antenna should be on the nose-cone end of the board. The
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antenna wire is about 7 inches long, and wiring for a power switch and
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the e-matches for apogee and main ejection charges depart from the
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fin can end of the board, meaning an ideal “simple” avionics
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bay for TeleMetrum should have at least 10 inches of interior length.
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There are two generations of the TeleMetrum design. The
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major changes after v1 generation are:
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* uBlox GPS chip certified for altitude records
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* Higher power radio (40mW vs 10mW)
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* APRS support
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Otherwise, they're the same size, with mounting holes and
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screw terminals in the same position.
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=== TeleMetrum Screw Terminals
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TeleMetrum has six screw terminals on the end of the board
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opposite the telemetry antenna. Two are for the power
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switch, and two each for the apogee and main igniter
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circuits. Using the picture above and starting from the top,
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the terminals are as follows:
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.TeleMetrum Screw Terminals
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[options="header",grid="all",cols="2,3,10"]
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|===
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|Terminal #|Terminal Name|Description
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|1 |Switch Output |Switch connection to flight computer
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|2 |Switch Input |Switch connection to positive battery terminal
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|3 |Main +++ |Main pyro channel common connection to battery +++
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|4 |Main - |Main pyro channel connection to pyro circuit
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|5 |Apogee +++ |Apogee pyro channel common connection to battery +++
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|6 |Apogee - |Apogee pyro channel connection to pyro circuit
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|===
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=== Using a Separate Pyro Battery with TeleMetrum
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As described above, using an external pyro battery involves
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connecting the negative battery terminal to the flight
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computer ground, connecting the positive battery terminal to
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one of the igniter leads and connecting the other igniter
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lead to the per-channel pyro circuit connection.
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To connect the negative battery terminal to the TeleMetrum
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ground, insert a small piece of wire, 24 to 28 gauge
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stranded, into the GND hole just above the screw terminal
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strip and solder it in place.
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Connecting the switched positive battery terminal to the pyro
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charges must be done separate from TeleMetrum, by soldering
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them together or using some other connector. Note that you
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must include a switch in the positive lead from the pyro
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battery for safety!
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The other lead from each pyro charge is then inserted into
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the appropriate per-pyro channel screw terminal (terminal 4
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for the Main charge, terminal 6 for the Apogee charge).
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=== Using an Active Switch with TeleMetrum
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As explained above, an external active switch requires three
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connections, one to the positive battery terminal, one to
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the flight computer positive input and one to ground.
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The positive battery terminal is available on screw terminal
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2, the positive flight computer input is on terminal 1. To
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hook a lead to ground, solder a piece of wire, 24 to 28
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gauge stranded, to the GND hole just above terminal 1.
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