osal Posted November 5, 2008 Share Posted November 5, 2008 Hi I did a site visit yesterday and noticed dimmer packs 4ch that ran 0- +20v down 8 pin din. But only 5 pins used has anybody else seen this? Are there any converts to make this useable? DMX or 0 - 10v thanks tom Link to comment Share on other sites More sharing options...
greenalien Posted November 5, 2008 Share Posted November 5, 2008 Most Pulsar analogue lighting desks use 8-pin din connectors for the analogue control signal. Link to comment Share on other sites More sharing options...
adamharman Posted November 5, 2008 Share Posted November 5, 2008 Most Pulsar analogue lighting desks use 8-pin din connectors for the analogue control signal. Most analogue desks and dimmers do, it's the 20v part that's unusual. Link to comment Share on other sites More sharing options...
osal Posted November 5, 2008 Author Share Posted November 5, 2008 yh I know pulsar did iv never seen the 20v part beforeI know of -10 - 00 - 10fmxand DMXbut o - 20 is strange Link to comment Share on other sites More sharing options...
The Gaffa Posted November 5, 2008 Share Posted November 5, 2008 I doubt very much if you'll have any luck interfacing them with DMX, but I stand to be corrected. I know some of the older Strand dimmers used to be -15v control before they changed to -10, and some of the other manufactures were +10v. +20v Control sounds like a Berkley system imported from the States back in the early '80's. If you can find out which manufacture the dimmers are someone may be able to help more. Link to comment Share on other sites More sharing options...
osal Posted November 5, 2008 Author Share Posted November 5, 2008 I and couple of work colleges have got our heads together and we will use a demux unit and 3x lm324 chips hence make it up 20v this should solve all problems. Link to comment Share on other sites More sharing options...
Kazeja Posted November 5, 2008 Share Posted November 5, 2008 Most manufacturers that I know of reserve one of the pins on an 8 pin din as power for a manual desk. and in early days used the chassis as reference. Any idea of manufacturer of the equipment? Link to comment Share on other sites More sharing options...
osal Posted November 6, 2008 Author Share Posted November 6, 2008 no it was unbranded had a very simmiler look to pulsar Link to comment Share on other sites More sharing options...
Neil Hampson Posted November 6, 2008 Share Posted November 6, 2008 The original Zero88 Demux48 (the chunky Grey one) has a jumper inside that will allows 3 voltage output ranges; 10V and 15V are definatly there, but I can't remember if 20V was the other option. I'm sure Paul or Keith will correct me if I'm wrong. One thing that you can do if you're competent with a soldering iron is use a non-inverting op-amp circuit to double up the voltage, the circuit is similar to the one used on the negative output kits. (LM324's I think) Ypu will probably even be able to use a neg output baord and just double the value of the input stage resistors to give you the 2:1 gain over a 0- 10V desk output. Link to comment Share on other sites More sharing options...
osal Posted November 6, 2008 Author Share Posted November 6, 2008 The original Zero88 Demux48 (the chunky Grey one) has a jumper inside that will allows 3 voltage output ranges; 10V and 15V are definatly there, but I can't remember if 20V was the other option. I'm sure Paul or Keith will correct me if I'm wrong. One thing that you can do if you're competent with a soldering iron is use a non-inverting op-amp circuit to double up the voltage, the circuit is similar to the one used on the negative output kits. (LM324's I think) Ypu will probably even be able to use a neg output baord and just double the value of the input stage resistors to give you the 2:1 gain over a 0- 10V desk output. yh thats what I was thinking Link to comment Share on other sites More sharing options...
Biskit Posted November 6, 2008 Share Posted November 6, 2008 Hi I did a site visit yesterday and noticed dimmer packs 4ch that ran 0- +20v down 8 pin din. But only 5 pins used has anybody else seen this? Are there any converts to make this useable? DMX or 0 - 10v thanks tom Hmm... I was about to suggest a 'dirty but might just work' method of controlling these dimmers from a 0-10V analogue signal (derived either from an analogue desk, or from DMX via a standard demux). It essentially involved making a basic op-amp amplifier with a gain of 2 (eg. http://biskit.pobice.co.uk/opamp.gif) however it has just occurred to me that op-amps run from a +/-15V supply, so the most they would get to is +15V (75% dimmer) and no higher! In principle it would be possible to offset the circuit ground levels to make use of the full 30V 'range' of the op-amp, but it is far too late at night to be dreaming of such circuits! Any electronic amplifier with a fixed voltage gain of 2, and capable of supplying +20V DC would work. Current flowing will almost certainly be negligible. Any suggestions anyone? Ben. Edit - Just noticed Neil already mentioned this option... I still think it isn't quite so simple with an op-amp! Link to comment Share on other sites More sharing options...
bruce Posted November 6, 2008 Share Posted November 6, 2008 4ch that ran 0- +20v down 8 pin din. But only 5 pins used has anybody else seen this? Are you sure it's 20V control? Did you get that from a spec or meter it? Lots of dimmers (pulsar and others) have/had a 20V (actually specced at 18-25V) supply available on one of the pins to power a desk, but the control voltage was still 0-10.... Link to comment Share on other sites More sharing options...
osal Posted November 6, 2008 Author Share Posted November 6, 2008 4ch that ran 0- +20v down 8 pin din. But only 5 pins used has anybody else seen this? Are you sure it's 20V control? Did you get that from a spec or meter it? Lots of dimmers (pulsar and others) have/had a 20V (actually specced at 18-25V) supply available on one of the pins to power a desk, but the control voltage was still 0-10.... it defo said operation 0 - 20 v on the unit I have spoken to someone else who has worked the venue before and he said that he eneded up using his own dimmers Link to comment Share on other sites More sharing options...
Biskit Posted November 7, 2008 Share Posted November 7, 2008 I've now slept on the op-amp idea, and I think if you strap the ground of your demux/desk and output signal to the dimmers to the -15V rail of the op-amp circuit, that should work. You would have to be very careful that the 0V rail in the op-amp circuit wasn't connected to any ground which could have a connection to the 'real' ground though (eg. through safety earth connections), but rather left completely floating. Create a 'virtual' ground half way between the + and - rails using two resistors (10k might work) in series and take 'circuit ground' as the point between them. It does get to the stage where you have to consider whether it is worth it. If you have the bits (one 4-way op-amp chip, 10 resistors, a bit of strip-board and a standard PSU would do four channels) and it is something you need to do regularly, it may be cheaper than hiring in alternative dimmers. If it is a one-off, and you have dimmers available anyway, it probably isn't. On the other hand, if it worked, could you get the venue to buy the device from you, for the benefit of other hirers? HTH Ben. Link to comment Share on other sites More sharing options...
osal Posted November 7, 2008 Author Share Posted November 7, 2008 Yeah that was my concern is it really worth the hassle. But I have other shows on at the same time and dimmers are going to be limited. I have worked there a few times but always used there control desk in the past but it is very limited and with it being a touring show I don’t want to have to program a desk at every location. Also there desk obviously can't handle DMX so I wouldn’t be able to use the Macs. D’OH! Why isn’t anything every simple? Link to comment Share on other sites More sharing options...
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