A block diagram is used to break down a system
into sub-systems that are easier to explain.
All
strobe lights will have the blocks shown in Figure 8.
The power supply, Block 1, can be either an AC
(Alternating Current) or DC (Direct Current) source of
electrical power. When a low voltage DC source is
used, a battery for instance, the voltage must be
“stepped up” to the proper high voltage required to
produce the avalanche process, as shown in Block 2.
After the high voltage is generated, a trigger pulse is
used to start the avalanche process (Block 3). Once
the gas in the flash tube (Block 4) is ionized, the
resistance of the tube drops and a large current flows
through the tube causing the high voltage to collapse.
The gas in the tube returns to its normal state (not
ionized) and the process starts over.
-5-
THEORY OF OPERATION
Figure 8
1
POWER
SUPPLY
2
GENERATE
HIGH DC
VOLTAGE
3
TRIGGER
CIRCUIT
4
FLASH
TUBE
BLOCK 1 - Since the power supply in this kit is a
battery, it is a DC source. The low DC voltage must
be converted to a high DC voltage required by the
flash tube.
BLOCK 2 - Figure 5 shows a fundamental high
voltage generator. In this kit, a transistor is used for
an oscillator (Q1 on schematic drawing shown
below). Q1 drives the primary of transformer T1 and
the secondary also steps up the voltage needed to
flash the xenon tube.
BLOCK 3 - The trigger circuit uses a neon light to
fire an SCR (Silicon Controlled Rectifier). The SCR
acts like a switch discharging capacitor C4 through
the primary of transformer T2. A high voltage spike
is produced on the secondary of T2. By using a
piece of wire, this trigger voltage is placed close to
the glass tube containing the xenon gas.
BLOCK 4 - The flash tube consists of a hollow glass
tube filled with Xenon gas and sealed at each end
with a metal cap. Wires are connected to each of
the metal caps. When a high voltage is placed on
one cap and the other cap is grounded, a strong
electric field will appear across the tube.
SCHEMATIC DIAGRAM
