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Analogue Woes

Tivoli Phil

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Hi all,


recently been working with a local ametuer company to help them sort out some "new" kit. 2 Strand Tempus dimmers (I can feel you all shudder at that) and an anytronics aurora 12 lighting desk. This is currently not playing and hasn't been for some time.


Firstly I thought it was the control voltages were not the same (desk 0 - +10v, dimmers 0 - -10v I think) so Mutley kindly built a voltage converter for me as a test run for the unit. The unit appears to work fine, but still nothing works.


If I plug an 8 pin DIN socket into the dimmers, and then plug the other end into anything, all the lights on that dimmer come on at full. If I swap pins 1 and 7 on the plug (I was getting desperate) then I can get control, but only at about 25% power.


Now I'm not really clued up on analogue gear, and am going by snippets of info from google, so anyone with any ideas of why this could be happening please step forward. I'd be very appreciative.





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If I swap pins 1 and 7 on the plug (I was getting desperate) then I can get control, but only at about 25% power.

Errr. on a Tempus pin 1 is channel 1 and pin 7 is power.





Ok, a few questions...


1) What are you powering the desk from? It needs 18-25volts at 70mA.


2) Without bringing the dimmers into the equation yet, are you sure the voltage inverter is working? If you put your multimeter on each output in turn, with the black lead of your meter on the 0v point, does that output go from 0 to -10 volts when you raise the associated fader on the desk?


3) How have you wired from the inverter to the dimmers? What pinout have you used? Have you read the pin numbering sequence on the 8-pin DINs correctly?




From the desk datasheet...




From the dimmer manual...



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I don't know if you've solved this yet but it's always worth remembering that a lot of Tempus racks had Technical Earth connected via the shield of the connector I.e the body of the plug and the socket and for this reason omitted TE on pin 8.


If you disassemble a Bleecon plug - there's a small tin ring with a tag that sits around the cable between the cable clamp and the pin retaining collar - I generally add a small link between pin 8 and that tab. I don't know why it was done - I first encountered it here when I started and was incredulous but tried it having been warned by the boss and it worked!! Nowadays - for the few cables we make for Tempus racks, we add the lnk at one end as a matter of course.

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Hi Guys,


Thanks a lot for the advice, having metered the voltage inverter, I don't think it's working, never got an readings off it so on presumes its not anyway. I have solved the issue with a very un-technical solution, I removed the Tempus racks and threw in some Pulsar Ratpacks to do the job. Everybody is happy.


I think the Earth connection to the chassis of the DIN probably was the issue, and I'll probably investigate this when I have some free time (so christ knows when).


Thanks again for all the advice guys,



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  • 1 year later...

I've realised that the first prototype of inverter circuit (Tivoli Phil mentioned) might have a design flaw in the power circuit. Like I said, it was a prototype and I was unable to test it after a change of career meant I had no access to dimmers to test it on!


However, I've recently designed, built AND TESTED (bench tested, but yet to try "in real life") a 24 channel control voltage inverter! It is mains powered and measures just 14cm x 10cm x 4.5cm (without any plugs in).




(It will obviously be fitted with a lid, but I'm waiting for a local engineering company to cut 8x 16mm holes in it for the DIN connectors. Drilling it manually might not give the desired finish!)


I've spent about 50 hours developing this to get it right, and Harry McBeal was the one who asked for it, so after his evaluation I might get a few made if it works well.


Just so I can gauge demand, could anybody who is interested in getting one (or more) of these please IM me? Price will depend on quantity produced, but as a rough guide price ~ £70. (With all the hours I've put into this, I'm not really making any profit! It's a double-sided computer aided PCB design, using 6x surface mount chips and 48x surface mount resistors (measuring just 2mm x 1.25mm), which all have to be soldered on by hand!)


Like I said, it's a 24 channel inverter, so there are 4x 8pin DIN sockets for 4x six channel dimmers. It inverts both negative and positive input, so you can use negative-controlled dimmers on a positive output desk/demux, or positive-controlled dimmers on a negative output desk/demux. (Incidentally, the DIN plug shield is also connected to the ground pin on all 8 DIN sockets).


I can also make a set of 8pin DIN control cables of any length to link it to the dimmers (at extra cost).




The next project will be an analogue relay switch to switch mains or low voltage when the input goes over about 50% (negative or positive). Any ideas? Single channel daisy-chainable? 6 channel?

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