Whiskers Posted July 24, 2014 Share Posted July 24, 2014 I would look up pin arrangements for all dimmers generally Zero and Strand follow Din PIN numbers Numbers which are crazy going round a socket clockwise 6 1 4 2 5 3 7 and 8 frame Pulsar ignore Din numbers and use geography 1 - 7 round the socket and 8 frame 7 and 8 are + from the dimmer and ground I would only connect + from the first dimmer of each split then take earth to both dimmers, be careful which is which 7 & 8 Good luck Link to comment Share on other sites More sharing options...
Ynot Posted July 25, 2014 Share Posted July 25, 2014 Hmmm... One thing you haven't clarified is what mains feed you're pulling the supply from. IF you have a 63A max supply (or 2 independent @ 32A) then running 8 x 300W cans on 6 channels would be OK - just - for a 230/240v supply. HOWEVER, the fact you have a 12 channel desk suggests you have another dimmer pack fed from channels 7 thru 12. Can we assume that you've got a separate and adequate supply for that one, and not tailing it off the same feed as the other one (or two)? As for whether the packs will take 8 x 300W cans on each channel, that will be close, and will depend on your supply voltage. 2.4kw from a steady 240v supply is right on the 10A mark whilst at 230v, that goes up to almost 10.5A... So running that many is going to be a judgment call after checking the supply. As others have said, in theory, running 2 packs from one control signal is doable, it's far from recommended as a professional approach. Link to comment Share on other sites More sharing options...
MarkPAman Posted July 25, 2014 Share Posted July 25, 2014 2.4kw from a steady 240v supply is right on the 10A mark whilst at 230v, that goes up to almost 10.5A... But a bunch of 300W lamps is just resistors. Decrease the voltage, and the current drops, therefore power does too. So the 2.4kW load on 240V, becomes 2.2kW at 230V with a current of 9.6A. If the voltage is higher though: 245V gives a load of 2.5kW for a current of 10.3A. * I have ignored the effect of temperature on the resistance, with will make these differences slightly smaller - but not much. Link to comment Share on other sites More sharing options...
Ynot Posted July 25, 2014 Share Posted July 25, 2014 2.4kw from a steady 240v supply is right on the 10A mark whilst at 230v, that goes up to almost 10.5A... But a bunch of 300W lamps is just resistors. Decrease the voltage, and the current drops, therefore power does too. So the 2.4kW load on 240V, becomes 2.2kW at 230V with a current of 9.6A. Will it? The more I look at this and tie my head up with the variables involved I'm rapidly coming to the conclusion that it's not one we can work out precisely without either a bench to test everything on at once or at least the behaviour of the resistance of the lamp itself. My conclusion was based on the assumption that a 300W lamp will dissipate 300W regardless of voltage, which of course it will not. So apologies for that misnomer. However, a lamp rated at 230V won't pull the same as one rated at 240V on the same supply - simplistically because the lamp's base resistance will be matched to the rated voltage to give the output required. But then pull into the picture the fact that running at full power the difference in the resistance of the lamp filaments CAN be quite significant - from memory I seem to recall resistance cold is about 10 or 12 times that of resistance when running hot, so that of course will play a part in the overall guesstimations. :) All of this is supposition and depends on a LOT of factors. Either way, though, my point is that the OP is getting very close to the point where anything critical shouldn't be loaded that close to the limit, and if he's loading ALL 6 channels of a six-pack that much then it's a potential invitation to fail... Link to comment Share on other sites More sharing options...
MarkPAman Posted July 25, 2014 Share Posted July 25, 2014 from memory I seem to recall resistance cold is about 10 or 12 times that of resistance when running hot Yes, but its graph is steep at low voltages (temperatures) but will be almost flat by the time you get to the "designed" operating voltage (and temperature). From 2.2kW to 2.5kW the change in resistance will be very small indeed. And in any case, reducing the voltage will never cause the current to increase. See thishttp://i61.photobucket.com/albums/h59/markpaman/tungsten-percent_voltage_var-_zpsa4cb1ed8.jpg Link to comment Share on other sites More sharing options...
Kazeja Posted July 25, 2014 Share Posted July 25, 2014 You may find that the more dimmers you hardwire to one control channel, the more the maximum output will decrease due to the loading on the control channel. I tried it once on a Strand 0 to -10v control signal and 4 dimmers. As the dimmers were added, the maximum output voltage from the control desk reduced to between -5 and -6v. Only way around it was to build a buffer to ensure all dimmers received the full -10v control sighnal. K Link to comment Share on other sites More sharing options...
J Pearce Posted July 25, 2014 Share Posted July 25, 2014 Interesting, when we did it we had 4 running with a drop to just over 9V, which was quite acceptable for what we were using it for.I believe it was from a zero88 desk into zero88 betapacks, perhaps they have a stronger supply or higher impedance input? I know some of the old old strand dimmers suck quite a bit of current on their control input. Link to comment Share on other sites More sharing options...
timsabre Posted July 25, 2014 Share Posted July 25, 2014 On recent equipment (within the last 20 years!) you won't have this problem. Most simple slider desks do not have any buffering on the output, they are just a 10K potentiometer, but the input impedance of the dimmer is pretty high. Link to comment Share on other sites More sharing options...
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