bigclive Posted July 5, 2016 Share Posted July 5, 2016 A while back someone mentioned they had been using the cheap eBay DMX buffer units. So I bought one to take apart and see what the circuitry was like.It's fairly standard. One proper receiver chip and eight proper driver chips for the outputs. Strangely the circuitry is based on a fully opto-isolated unit, but with both sections fed from a common power supply. (So not isolated at all) I'd say that with a good brand of power supply these would be a useful little addition to a DMX tool box. Here's the video of the teardown. https://www.youtube.com/watch?v=kq4nU--hUAI Link to comment Share on other sites More sharing options...
musht Posted July 5, 2016 Share Posted July 5, 2016 Now that is fascinating, if only they realised could multiply price by 20 putting it in a rack mount box with 5 pin connectors ;-) Card is a handy size for re-installing in other things as well. Thanks Clive. Link to comment Share on other sites More sharing options...
alistermorton Posted July 5, 2016 Share Posted July 5, 2016 Card is a handy size for re-installing in other things as well. Such as a rack mount box with 5 pin connectors - business opportunity http://www.blue-room.org.uk/public/style_emoticons/default/laugh.gif Link to comment Share on other sites More sharing options...
musht Posted July 5, 2016 Share Posted July 5, 2016 Thinking tidying up Par bars, sure most LED Pars have power and DMX I/O but so much neater with IEC/powercon socket and XLR to each point. Link to comment Share on other sites More sharing options...
ABlackmore Posted July 5, 2016 Share Posted July 5, 2016 Somewhat embarrassed that it's taken until now for me to make the connection that the BigClive I'm subscribed to on youtube is the same BigClive I see here on the Blue Room... http://www.blue-room.org.uk/public/style_emoticons/default/biggrin.gif Link to comment Share on other sites More sharing options...
bigclive Posted July 5, 2016 Author Share Posted July 5, 2016 Somewhat embarrassed that it's taken until now for me to make the connection that the BigClive I'm subscribed to on youtube is the same BigClive I see here on the Blue Room... http://www.blue-room.org.uk/public/style_emoticons/default/biggrin.gif I'm all over the Internet. Like a rash. Link to comment Share on other sites More sharing options...
Don Allen Posted July 5, 2016 Share Posted July 5, 2016 One design reason for the use of bridge rectifiers in DC powered equipment is to protect against someone using the wrong polarity DC supply lead and also to protect against someone using an AC output adaptor. Link to comment Share on other sites More sharing options...
alistermorton Posted July 6, 2016 Share Posted July 6, 2016 Indeed, but I think Clive's question in the back of his mind was would it still isolate the input and output side in the event of a fault. One design I saw for a homebrew buffer had 1 in 3 out and 4 separate power supplies in the box, the only common connection being the mains in but each module (input or output) having a separate small transformer feeding the linear regulator, and optical isolation between all channels.. Edit: speeling. Link to comment Share on other sites More sharing options...
Stuart91 Posted July 6, 2016 Share Posted July 6, 2016 So the conclusion I'm drawing from this discussion is that these would be fine for use in small venues / shortish runs, where you're not going far enough to encounter too much voltage between the earths? Card is a handy size for re-installing in other things as well. Is it reasonably easy to source flying leads with the molex-style connectors to extend onto different XLRs? Link to comment Share on other sites More sharing options...
timsabre Posted July 6, 2016 Share Posted July 6, 2016 So the conclusion I'm drawing from this discussion is that these would be fine for use in small venues / shortish runs, where you're not going far enough to encounter too much voltage between the earths? Not really. The isolation is useful to prevent damage when you get a fault and this can happen in any size of rig. It's just a 2nd line of defence against problems really, the decision you have to make is whether to pay extra for isolation to give you that extra defence... Link to comment Share on other sites More sharing options...
Stuart91 Posted July 6, 2016 Share Posted July 6, 2016 That makes sense, I guess. What sort of fault / circumstances would give rise to a situation where the 2nd line of defence is necessary? Link to comment Share on other sites More sharing options...
timsabre Posted July 6, 2016 Share Posted July 6, 2016 That makes sense, I guess. What sort of fault / circumstances would give rise to a situation where the 2nd line of defence is necessary? Anything that causes an earth potential basically. E.g. a mains short to earth can cause a large spike of voltage on the earth which can destroy the DMX chips in nearby fixtures with that earth.Also shorts on DMX lines and things like that. Link to comment Share on other sites More sharing options...
Yorkie Posted July 6, 2016 Share Posted July 6, 2016 Realistically would this sort of thing in a 1U case with 3 and 5 pin connectors be a good bet for a cheap splitter? https://www.bax-shop.co.uk/DMX-peripherals/showtec-db-1-4-DMX-512-booster-splitter Link to comment Share on other sites More sharing options...
revbobuk Posted July 6, 2016 Share Posted July 6, 2016 Realistically would this sort of thing in a 1U case with 3 and 5 pin connectors be a good bet for a cheap splitter? https://www.bax-shop.co.uk/DMX-peripherals/showtec-db-1-4-DMX-512-booster-splitter If you subscribe to Clive's YooChoob channel, you will see that he has reviewed that very device, and was quite complimentary about it. Link to comment Share on other sites More sharing options...
Yorkie Posted July 6, 2016 Share Posted July 6, 2016 Realistically would this sort of thing in a 1U case with 3 and 5 pin connectors be a good bet for a cheap splitter? https://www.bax-shop.co.uk/DMX-peripherals/showtec-db-1-4-DMX-512-booster-splitter If you subscribe to Clive's YooChoob channel, you will see that he has reviewed that very device, and was quite complimentary about it. Thanks, I am a subscriber, just don't remember it. Apologies, will search properly! Link to comment Share on other sites More sharing options...
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