Circuit Boards and Sensor/Initiator Circuitry > Light Level Falling > Light Sensitive IED
Product Code: ITA-111
Circuit Boards and Sensor/Initiator Circuitry Item Description:
Training models ITA-110 (light level rising) and ITA-111 (light level falling) are built around very similar circuitry. In ITA-111 the sensor and electronic circuitry are almost identical to the setup in ITA-110. The circuitry is designed to close the relay contacts when the light level on the sensor surface drops below a preset intensity threshold. In all other respects, the description for ITA-110 applies similarly to ITA-111.
These circuits use similar circuit and operate on a photo resistor sensor that detects light level. The circuit boards each have an adjustment. The variable resistor on the circuit boards allows for the instructor to pre-set the level at which the ITA-110 circuit will trigger a relay and detonator when the sensor is exposed to a light level higher than preset; the ITA-111 circuit board will trigger the closure of relay contacts when the sensor detects light level exposure to less than the preset light level setting.
Both circuit boards also contain an adjustable time reset feature allowing the instructor to set a delay ranging from 1 second up to 15 seconds, before automatically resetting to standby mode, awaiting the next change in light level for classroom demonstration.
Both circuit boards can be activated and demonstrated by the instructor, by shining a light on the sensor or taking the light away, or shutting off the room lights or opening a curtain or blind. The photo resistor senses the light level change and its resistance changes accordingly. The circuitry interprets this change in electrical resistance and operates the relay contacts. A separate power source is wired through the relay contacts, and to an inert detonator containing and LED, for visual indication of electrical continuity, and to a small piezo whistle for an audible indication of continuity. These two indicators simulate “detonation”.
In ITA-111, the circuitry is designed so that it triggers when the circuit board (and improvised explosive device) are moved from a location where the light is bright, to an area of reduced or subdued light, shadow or darkness. The light level drop can be set using the two sensitivity settings. They have been factory set for normal room light at our location but may have to be reset by you. It is recommended that you make a sketch of the adjusting screw slot position on each of the two potentiometers (variable resistors) before any adjustment is made. Otherwise, you may have trouble returning to the factory setting.
Turning off the lights, saving the training aid from bright light to shadow, or passing your hand over the sensor surface to reduce the intensity of light falling on it, will close the relay contacts and trigger the LED in the detonator.
The POWER toggle switch and the ARM-SAFE toggle switch should be shutoff and set to safe before connecting the batteries into the circuit.
Remove both batteries from the circuits by unsnapping the terminal strips, for storage or transport.
Use only a fully charged battery in each part of the circuit, or operation may be unreliable or unpredictable. We recommend alkaline batteries be used. If you have a battery tester or a volt meter, batteries should test at 8.75- 9.5 volts. At lower than 8.75 volts, the circuitry may not function.