Thhe circuit provides for Dimmers, or possibly VCAs, requiring a ramped voltage of 0 to +10v DC. When a closing contact (or open collector to ground) is applied to the input the ramp will move up, when the ground is removed the ramp moves back down. The maximum "on" voltage can be adjusted via a preset on the board, as can the speed of the ramp. The control is via an Opto Isolator driven from an on-board +5v rail, thus effectively isolating the switching voltage from the ramp voltage and reducing the chance of interference finding its way back to the source. There are 11 sections on the PCB providing feeds for up to 11 dimmer packs. The board can be cut in at any section thus increasing its flexibility. As standard we supply the board in the full 11 stages but other combinations can be supplied to order.
The board requires +/-12v DC to operate, it also requires +5v but this is stepped down from the +12v via an on-board regulator.

The board is primarily intended for exhibition or museam use where a Telephone Handset of Headphones are to be used to monitor the output of a SoundStore, CD, etc. The amplifiers are 1W and can drive a small speaker at reasonable volume.
The board will run from a PSU as low as 5v if required.
Having DC control means that even if the potentiometer gets worn it should not cause degredation of the output signal.
The PCB is laid out such that the DC input connector (2.1mm concentric, centre +5), the phono connectors, the volume pot(s) and the 1/4" jacks are in a line, thus making it easy to house the PCB.
Each PCB contains 4 x 1W amplifier modules with a common DC volume control. The stereo phono inputs are mixed such that Left and Right are applied to each amplifier module.
The board can be configured such that if a link is cut, a second pot can be added to control left and right channels independantly.
The output jacks(1/4") carry the amplified mono signal, either 4 mono or 2 left and 2 right.