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Analog Dimmer Control

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Analog dimmer control is all about using an analogue control voltage to proportionally dim a lamp. Most systems use a common standard, which uses 0V to represent full off, and +10V to represent full on. There are, however, a number of exceptions...

ManufacturerFull Off
Full On
Spectrum QEP10V0V

Of course, I've never actually seen most of the real oddballs (or even an EDI) so all corrections and suggestions for additions are welcomed, just mail the webmaster.

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Bleecon connectors

piccie of a Bleecon ditto

Bleecon connectors ("Bleecons", by Belling Lee) are widely used on dimmer packs of six or less channels for analog control input. The Bleecon is basically an 8 pin DIN plug and socket. The sockets will accept ordinary 8 pin DIN plugs, and also those with a locking ring, the advantage of the Bleecon plug is it's easy pull to release lock mechanism.

Like all good widely used connectors, there are a few variations by manufacturer of just what the various pins do...

[Note 1]
1Channel 1
2Channel 2
3Channel 3
4Channel 4
5Channel 5
6Channel 6
7Power [Note 2]


  1. What is standard? Most manufacturers seem to follow this pinout
  2. Power polarity tends to follow control polarity, so Strand supply -ve power here, everyone else supplies +ve power.

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AMX192 - Analog Multiplex Data Transmission

AMX192, (a USITT standard) was devised to multiplex up to 192 analog dimmer levels down a four wire cable. The four wires are ground, analog level, and a differential clock. The USITT standard is now quite old, having been last revised in February 1987, and is probably now mostly of historic interest, although there are many thousands of installations out there which use this protocol every day, there won't be many more newly installed systems. DMX512 is now the protocol of choice for multiplexed lighting control. The AMX192 standard document is bundled in from USITT with the DMX512 standard document

The standard says...:

2.0 Applicability

This Standard is intended as a guide for:

  1. Equipment manufacturers and system specifiers who wish to integrate systems of dimmers and controllers utilizing analog multipled control.
  2. Equipment manufacturers seeking to adopt a basic controller-dimmer analog multipled data transmission protocol

It is important to note that the origins of this standard come from a control protocol originally developed by Strand Lighting (Strand Century Inc.). This protocol is used by a large installed base of equipment manufactured by Strand and many other manufacturers. One of the objectives of the Standard is to describe a protocol that will sucessfully communicate with most of this existing equipment. Because the original protocol has undergone many slightly different versions, this Standard is broken down into two major areas:

  1. Receive Timing. Dimmers or other receiving devices that adhere to these timing requirements should be able to successfully communicate with most existing consoles that use different variations of the original Strand protocol.
  2. Transmit Timing. Controllers or other transmitting devices that adhere to these timing requirements should be able to communicate with most existing dimmers that use the different variations of the original Strand protocol.

There are substantial differences between the receive timing and the transmit timing. New controllers adhering to this standard must produce a signal acceptable to a wide variety of dimmers, and new dimmers must be able to listen to a number of different controller signals. As an example, note that new controllers should provide a wide "analog valid" window, but new dimmers must be able to cope with the differences in existing consoles, and use a narrow "sample window". These differences in timing between the Receive Standard and the Transmit Standard produce enough tolerance to cover worst case variations on the original Strand protocol.

Although widespread adoption of this Standard is sought by USITT, compliance with the standard is strictly voluntary. Furthermore, it is not intended as a replacement for existing protocols already manufactured, but rather as an addition to existing protocols which will broaden the installed base of controllers and dimmers that can communicate with each other.

One real gotcha with all the multiplexed analog schemes is that the cable radiates a fair amount of interference, and so wireless intercomms can get blocked if you are close by.

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AMX192 four pin XLR pinout

1Signal common
2Differential clock +ve
3Analog level
4Differential clock -ve

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