Envco – Environmental Equipment

• Accurate Timing - The Timer Starts At The First Contact Closure
• User Selectable Contact Debounce Time
• Counts up to 40 Pulses per Second
• Battery voltage displayed on power up
• High Temperature LCD Display
• Designed To USGS Specifications
• Robust Construction & Adjustable Neck Strap

OPERATION:
The CMC20A operation depends on four major functions which can be illustrated as follows:

ON/OFF Switch:
It is used to turn the counter on. However, timing will not start till the first contact closure is detected.

Start Button:
Resets the display and prepares for the preset time interval. (The colon on the display indicates that start has been pressed) Note : Timing commences on the first detected contact closure. The count will not increment on the first closure, only subsequent closures. This ensures that timing is accurate.

Stop Button:
Stops further counting - and allows the counter to be reset and restarted by the Start switch.

Rotary Switch:
Selects a range of preset time periods and the integrate mode for use with ground-feeler weights. This robust counter displays the accumulated pulse count generated by the current meter for a range of preset time periods. Each pulse represents a full revolution by the propeller. “INT” mode is included for depth measurements with ground-feeler weight. In this mode the buzzer sounds continuously while the contacts are closed and counting continues until interrupted manually by the “Stop” switch.

SPECIFICATIONS:
Housing: Submersible powder coated aluminium die cast case with nylon webbing adjustable neck strap.
Dimensions: 160 x 100 x 55mm (6.3" x 3.9"x 2.2")
Weight: 1 Kg (2.2 lbs)
Display: 4 Digit High Temperature liquid crystal display rated to 80oC.
Accuracy: ±0.1 seconds (Timed from first contact closure); ±1 pulse
Timer: Quartz crystal accuracy, better than 1 in 20,000.
Preset Facility: Time intervals of 10, 20, 30, 40, 50, 80, 100, 200 and infinity seconds.
Infinity Mode: INT. This mode is used for depth measurements with ground-feeler weights, manual operation of counter or integration measurements

Operating
Temperature: -20oC to 70oC
Humidity: 0 - 100%
Contact Debounce: The current meter pulse is debounced in software. The debounce time is user selectable. (1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45mS) This is useful for a meter with a mechanical “cat whisker” contact wire.
Buzzer: Instantaneous beep for each current meter pulse except in the integrate mode - in this mode, the buzzer gives a continuous beep while the current meter switch or ground feeler weight switch is closed.

Power Supply:
9V DC - 6 AA Alkaline batteries (or 6 AA Nickel Metal Hybrid). The actual battery voltage is displayed for 2 seconds each time the unit is switched on. Low voltage is also indicated by all decimal points showing on the display at 5.8 volts.
Packed Dimensions: 260 x195 x 160mm (10.2"x7.7"x 6.3")
Packed Weight: 1.3 Kg (2.9 lbs