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Author Topic: Multi 7 way switch  (Read 1981 times)

cos918

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Multi 7 way switch
« on: March 13, 2016, 08:56:17 PM »

Hi All
I have brought this 7 way switch . Question can it work with a common negative. or does ever lighting circuit have to be separated on both negative and positive .


http://www.ebay.co.uk/itm/191443172222?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


John
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JimG

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Re: Multi 7 way switch
« Reply #1 on: March 13, 2016, 09:33:19 PM »

Hi, this appears to be the same as the one sold by Hobbyking. The negative is common on the circuit board as the power to the lights is provided by the input on the board. Only the positive supply is switched. You can check yours by looking at the bottom of the circuit board. You should see all the negatives go to a single track.

Jim
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cos918

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Re: Multi 7 way switch
« Reply #2 on: March 14, 2016, 05:24:31 AM »

Hi Jim
thanks for the info . I will have a look at my one .


john
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malcolmfrary

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Re: Multi 7 way switch
« Reply #3 on: March 14, 2016, 08:39:37 AM »

On the link provided there is a link to the instructions - http://www.sedwards.me.uk/ebay/downloads/Multi-remoteRCSwitchv2updated.pdf - A quick look showed the options but didn't state specifically what the outputs actually were, whether they were capable of directly switching power or were just logic level outputs intended to control actual switching devices.
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JimG

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Re: Multi 7 way switch
« Reply #4 on: March 14, 2016, 10:00:55 AM »

It is switching the input supply (6 - 12V) to supply low current draw devices. Each output can supply a bulb or LED as long as the current draw is within the allowed limit (500mA ?)

Jim
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John B

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Re: Multi 7 way switch
« Reply #5 on: August 20, 2016, 10:59:08 PM »


Hi John & Jim
'Hoping one or both of you might still be around here for some suggestions or confirmation.
I have (presumably) the same multi switch - at least it looks externally identical.  Mine seems to have all 7 outputs common positive (even though the main circuitry of the board has negative ground).  This won't work with my boat's 5 main lighting circuits which are LEDs connected common negative.  In effect this parallels all the outputs from the multi switch and it simply acts as a single switch in this case.  Am I right in thinking that I can't change the outputs to produce 7 independent switched positive outputs?  My tug is all metal and the lighting circuits are one-wire with negative ground.   Changing them would require rebuilding mast lamps, re-painting, etc. I like this multi switch and would much prefer using it instead of a servo with cams and bank of micro switches.    A second question for John - did you find that the published tables for the switching sequences are not correct and that your unit has different (and I think more useful sequences) and also includes two tracer sequences (switch positions 4  & 9)?   Any comments, optimistic or otherwise would be appreciated!   - John
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malcolmfrary

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Re: Multi 7 way switch
« Reply #6 on: August 21, 2016, 09:15:27 AM »

If the outputs are switched positive, but switched negative is needed to match the existing installation, use one of these - http://www.technobotsonline.com/uln2003a-7-way-matched-npn-transistor-array.html - between the switcher outputs and the wiring.  It will need a few minutes work with a bit of stripboard but you wind up with 7 ground backed outputs each capable of half an Amp.
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John B

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Re: Multi 7 way switch
« Reply #7 on: August 21, 2016, 06:38:04 PM »

Malcolmfrary thank you for your prompt reply.  The 7-way NPN transistor array which you suggested looked to me at first like the perfect gadget to solve my problem. Fortunately your suggestion motivated me to try acquaint myself with modern switching circuits.  However after some study this morning I now realise that I would apparently instead need a "high-side" driver (common negative, with switched positive outputs).  It seems that these high-side switch arrays are more difficult to source, usually require extra circuitry and positive output switches have a greater voltage loss.  The ideal device would also need to invert the sense as it will be receiving negative pulses to turn it on.  I could do this but it would require a separate power supply for the lighting, which I was hoping to avoid (a steam tug with as few batteries as possible!).  Now I understand why the original RC Multi-Switch which I purchased was made with common positive outputs (easier).  Don't worry - I didn't know any of this until after your message got me digging around the internet this morning - I thank you for getting me thinking :-)
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