APF Spectrograph Electronics
Page last updated: August 22, 2012
The EL-1398 8-Channel AC power controller box is a small, 1U format, unit capable of switching off and on eight AC outlets via open-collector inputs. The box was designed and fabricated for the APF spectrometer project but the design is general enough that it can be controlled by any source supplying open-collector signals. There are eight AC output receptacles and two power cord sockets located on the rear panel of the box. The two inputs each feed four output receptacles and are fused at the front panel. Normally the circuits are fused at 3A but this can be changed to up to 15A as need for the specific purpose. The input connector is a DB-15P with 8 inputs and 7 grounds. The connector is mounted on the front panel. Pins 1 through 8 correspond to the 8 channels and pins 9 through 15 are the grounds. Also mounted on the front panel is a 3-pin MS connector that supplies the 3-32VDC required for the solid-state relays that pass the 110VAC to the outputs. NOTE: The status indicator LEDs on the front panel are wired with a series resistor selected for a 5VDC power supply input. If you use the box with a different supply voltage the resistors will need to be changed accordingly. Lastly, the front panel has a set of eight LEDs numbered 1 - 8 that correspond to the eight channels. As the input signals are open collector, pulling the input to ground will turn one the channel and illuminate the front panel LED. Internally, the box consists of the eight Crydom D1225 solid-state relays and two terminal strips. The shorter strip, TB1, distributes the DC voltage to the relays and LEDs. The longer strip breaks out the DB15 connector wires. The first sheet of the schematic details the input wiring and output wiring for channels 1 - 4. The second sheet details the wiring for channels 5 - 8.
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