The Flashtube; Led Beacon; Timing Circuit - TWR Lighting E-1DBSL Manual

DUAL MEDIUM INTENSITY LED/STROBE
3.2

THE FLASHTUBE

The flashtubes FT1 (daymode) is a quartz tube containing two (2) electrodes. The
electrode at the positive (+) end is called the anode and is connected to the positive
side of the storage capacitors through inductor L1. The electrode at the negative (-)
end of the tube is called the Cathode, and is connected to the negative (-) side of the
energy storage capacitors banks.
The flashtube contains a gas called Xenon. When the high voltage energy in the
storage capacitors is connected to the flashtube, nothing will happen since Xenon in
its natural state is not a conductor of electricity. However, when a very short duration
high voltage pulse is impressed on the trigger element of the tube (via the power
supply and trigger transformer T4), the Xenon gas is ionized and thereby becomes a
good conductor of electricity. This allows the electrical energy in the storage
capacitors to discharge rapidly through the flashtube, which converts this energy to
light energy and heat energy. When the voltage stored in the capacitors discharges to
a low level, the Xenon gas can no longer sustain conduction and since the short
trigger pulse is gone by this time, it deionizes returning to its non-conducting state
until another trigger pulse arrives to repeat the process. Meanwhile, the storage
capacitor is being recharged by the transformer and the high voltage rectifiers.
3.3

LED BEACON

When the photocell turns on at nightfall, that sends 120V AC to Relay K3, and
energizes it. The power is switched to red beacon control circuit. That consists of a
flasher (M3), a timing module (M4), and a current sensing module (M2). These
modules are used to flash the LED Beacon and detect the failures, as well.
3.4

TIMING CIRCUIT

The timing circuit is contained entirely on printed circuit board #1. The timing
circuit has its own power supply. This circuit converts the AC voltage to
approximately 12V DC, which is used to supply all of the components in this circuit.
It uses this low voltage DC to generate pulses that control the flash rate of the
flashtube. It actually generates two (2) groups of pulses. The first is a pulse
approximately once every 1.5 seconds to operate the flashtube during daylight hours.
The second is a burst at 100 Hz to elongate the apparent flash during the nighttime
hours at reduced flash energy when it failsafes in nightmode.
M.E-2018.E-1DBSL
11-11-08 REV 1-19-18
MODEL E-1DBSL
10