Instruction manual

4.0 Theory of Operation Cross Technologies 1582-70L Switch
4.1 Introduction - The 1582-70L Switch provides automatic and manual control of RF sources or loads
depending on the user's application. Automatic control is facilitated by monitoring of alarm inputs and
selecting the initial RF source. Local and remote control of RF sources is also provided. LED indicators are
provided for Alarm and Alarm History ("CH1" and "CH2"), Power ("CH1" and "CH2"), Remote, Manual as
well as "CH1" and "CH2" Select. Latching relays are an option that allows the switch to remain in its "current"
state independent of power loss.
4.2 Circuit Description (Refer to Switch Matrix)
4.2.1 Auto Operation
Assume that the jumper and switch settings are configured for "Normal Auto Switch Setting" as shown at the
bottom of the matrix unless otherwise specified.
Alarm inputs "1" and "2" are monitored by the "Auto Latch" (U4). This latch will only change states when the
selected source is in an alarm state and the unselected source is in a not alarmed state. The alarm inputs first
pass through U1A and U1B where they are either inverted (Low = Alarm - JP1 1-2) or not inverted (High =
Alarm - JP1 2-3). The output of U1A (pin 3) is the Alarm 1 status where High = Alarm. The output of U1B
(pin 6) is the Alarm 2 status where High = Alarm. These outputs then go to inputs on U6 and U4. A logic Low
on the output of U4A (pin 3) = "1" is alarmed AND "2" is not alarmed. In this case the Auto Latch (U4) will be
set to select "CH2". A logic Low on the output of U4B (pin 6) = "1" is not alarmed AND "2" is alarmed. In
this case the Auto Latch (U4) will be set to select "A". If both alarm inputs are alarmed or both alarm inputs are
not alarmed, the Auto Latch will not be affected. The output of the Auto Latch (U4 - pin 6) determines which
RF source will be selected (in auto mode only) where a logic High = Select "CH2".
The Auto Latch logic then passes through the remote control circuitry, which without remote control asserted,
will not affect the logic levels. After the remote circuitry the logic signal passes through the manual control
circuitry, which without manual control asserted, will not affect the logic levels. After the manual control
circuitry, the logic is either applied directly to the relay drivers (High = Select "CH2") for non-latching relays or
is routed through U9A and U10 for latching relay versions.
For models with latching relays the logic signal first passes through U9A that provides a relay pulse to ensure
that the relays will all be set to the same state on power-up. R28 and C7 provide a pulse to the dual "one-shot"
(U10) The outputs of U10 provide the relay set (U10 pin 6) and reset (U10 pin 10) pulses for the latching
relays. A "Set" pulse selects "CH1" and a reset pulse selects "CH2". U12A and U12B provide a "lock out" that
eliminates the possibility of a set and reset pulse occurring simultaneously by "resetting" each other's "one-
shot" during a set or reset pulse.
1582-70L Manual, Rev. B Page 12 11/05/09