GESCOMP
Compass and Relay Board Interface
Description:
The DTEC Ltd. GESPAC compass board interfaces a flux-gate sensor which
outputs a sin and cosine levels providing amplification and buffering. The connection
to peripheral equipment is provided by the screw type terminal strips. This
board allows adjustment of the gain and bias of sin and cosine independently to
provide proper input levels to the telemetry. There is also a provision for 6
relay outputs on the board which can be controlled externally and provide a
30VDC @ 1Amp output. From DTEC the
boards are set to range from -1.00 VDC to +1.00 VDC on the sin and cosine
channels. However each sensor may be slightly different and as a rule the board
usually has to be recalibrated with the specific sensor to be used. On the
board there is a provision to mount the sensor or it can be mounted remotely
through a ribbon cable type connection. Because the sensor must be installed
and rotated to a known heading it may be more convenient to mount the sensor
remotely. The board requires +12-15 VDC, -12-15 VDC and ground from an external
supply to operate.
Circuit Description:
The circuitry for the sin and cosine values are the same, so the
following applies to both. The first stage is an unity gain inverting op-amp
circuit to produce the proper levels for the gain and bias stage. This gain and
bias stage consists of a bias adjustment resistor network (P1,R7 and P3,R16),
inverting op-amp circuit and the gain adjustment feedback circuitry (P2,R2 and
P4,R11). The capacitors in both feed back stages are used for filtering out
high frequencies. After this last stage the output select jumpers must be in
place. These jumpers allow the sin or cosine voltage levels to be exchanged to
be on 4 or 5 of the terminal block or visa versa depending on the orientation
of the sensor. If the sensor is placed upside down (the compass rotation will
be wrong) the sine and cosine will have to be swapped. A 78L05 has been
installed to provide +5 Vdc for the sensor. An illuminated LED indicates proper
+12 VDC power into the board.
Relays:
6 relays have been added to the last revision. These are 12VDC coils and can switch
30VDC/120VAC @ 1 Amp.
Stock Item. US$180.00
For Schematic and General Arrangement in DXF format go to the download
page.
|
Connector P1 Screw Type Term Block |
Description |
|
1 |
+12 Vdc - Vcc |
|
2 |
-12 Vdc - Vdd |
|
3 |
Ground - Power Supply Common |
|
4 |
+5Vdc Output Power - 7805 |
|
5 |
Sin /Cosine Output |
|
6 |
Sin / Cosine Output |
|
7 |
Sensor Raw Sin Value |
|
8 |
Sensor Raw Cosine Value |
|
9 |
Ground - Power Supply Common |
|
10 |
Not Used |
|
11 |
Not Used |
|
12 |
Not Used |
|
13 |
Not Used |
|
14 |
Not Used |
|
15 |
Not Used |
|
16 |
Relay 2 Control Input |
|
17 |
Relay 1 Control Input |
|
18 |
Relay 1 &2 Normally Open Output. (+5 Output if switched) |
|
19 |
+5 Vdc Output |
|
20 |
Relay 1 & 2 Normally Open Output. (Common if switched) |
|
21 |
Ground - Power Supply Common |