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gilou edited this page May 15, 2018 · 5 revisions

The analog shield

Todo list

  • Update with new schematics and new references
  • Build welding instructions
  • Use local pictures

Blocks description

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global

The leaf shield.sch brings together the connectors and the different functional blocks. The input connectors on the right are 5.08mm pitch screw terminals for connecting the different sensors. The connectors on the left are 2.54mm pitch type connectors.

A two-screw terminal block (5VDC101) is present allowing a power supply of the card with a voltage of 5V. Two filter capacitors are connected between + 5V and GND. The values of 10uF and 100nF were chosen by experience

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The RPM101 connector is used to connect a rotation sensor, it has a GND terminal, + 5V and an RPM signal terminal connected to + 5V by a pull-up resistor. This sensor is not defined, this configuration seemed optimal.

Anemometer

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Hall effect: This treatment is mainly used with anemometers type NRG40c, generating a sinusoid whose frequency is proportional to the wind speed.

ILS: Anemometer with output either ILS or open collector, a simple pull-up resistor have to be used. (330 Ohms in the case of a NRG 40H under 5V)

Windvane

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A wind vane behaves like a potentiometer, but to be able to rotate continuously, it has a dead band so that it doesn't have a short-circuit when its cursor goes back to 0. Two resistors of 100 Ohms are used to cover this dead band in terms of values but also protect against short circuits.

Voltage sensors

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  • AC voltmeter It is a transformer serves as an alternating voltage sensor. A model assigned to a 9V voltage image was chosen. Type: Ideal Power Ltd. 77DE-06-09

The principle here is to have an image of the voltage UAC_in output in a voltage range between 0 and + 5V.

  • DC voltmeter Depending of the installation, the value of resistance R401 allows to measure different voltages. For installation on a 12V isolated site, for example, use a 150k ohm resistor. In stand-alone operation, a 60 kOhm resistor can monitor a 4 * AA battery pack.

Changed for:

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Current sensors

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The sensors used can be for alternating currents or for continuous currents: Continuous current: Lem Hass 50-s, -50 / + 50A possible. Lem HTFS 200, -200 / + 200A possible. Alternating current: SCT-013-000, 0-100A possible, choose the burden resistor for the precision.

  • DC operation To use the Hass 50-s or HTFS 200 LEM probes, no burden resistor is needed, the sensor provides directly an image voltage centered on + 5V / 2 provided by Ix_lo.

  • AC operation The resistor called "burden resistor" makes it possible to obtain an image of the current coming from the sensor. The value of this resistance varies according to the amperage

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Welding instructions

The instructions o weld the board are HERE.

Bibliography

The project bibliography is availlable HERE.

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