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Author Topic: Voltage at end point?  (Read 901 times)

Brian60

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Voltage at end point?
« on: September 15, 2017, 11:24:29 AM »

I have 'x' amount of led's each voltage lowered by resistors in the positive side - down to 3v each. The negative side of the 'x' amount, lets say there are 4 to make things easy, go to a switching module.

The four negative legs of the leds all tie in to one end point of an electronic switching module 4 into 1.

What is the voltage seen at that 1 endpoint please? My mind is saying 3volts ( in parallel) but something is saying 12v ( in series)

Its important as I cannot overload the switching unit which itself is built for turning on/off multiple lighting circuits, each of its inputs is limited to 12v, there are 8 inputs. So 8 12v inputs. Can I double up so its 16 6v or 32 3v? Sorry but the instructions with the unit are none too clear on this point.

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Re: Voltage at end point?
« Reply #1 on: September 15, 2017, 11:43:26 AM »

Hi Brian,

What's the switching unit?

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Brian60

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Re: Voltage at end point?
« Reply #2 on: September 15, 2017, 01:27:52 PM »

I've attached a pdf of it Jonathon. There was only a production run of 20 units made for a German club. I was fortunate to be in a position to buy the last unit that was made. I bought it back around 2014 for my POSH Venture but the wiring was too far developed to add it in. My current build is at a point where I have to decide on pre wiring the lighting and as this unit is going into it, I want to know whether I'm going to be able to do it the easy or hard way when it comes to the led's.

The reason I bought it was because it uses leds to mimic real lighting, flourour tubes, Sodium lights, neon lights, etc. FOr instance the sodium lights, flicker and then burst into light and then when turned off die out slowly just like the real ones do. It can flicker leds to mimic faulty flouro tube lights. read the sheet and you should understand.

Brian60

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Re: Voltage at end point?
« Reply #3 on: September 15, 2017, 01:55:51 PM »

Here's a very short video of it in operation...

https://www.youtube.com/watch?v=nTqvGR8u92E

and a photo of the unit itself.. You'll see how he has 1 led per input. I'm thinking you should be able to get 2 or more per input. preferably wired singly, but even if they need daisy chaining together in groups of 2/3 or more.

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Re: Voltage at end point?
« Reply #4 on: September 15, 2017, 02:27:04 PM »

What bulbs are you using - voltage? - current drain?
Ampage draw is what you need to worry about as long it doesn't exceed the limit for desired output.
The pic above i am presuming is set up as a demo to show what each output can do via 1 LED, you can have as many as you like as long as current draw is not exceeded.
Plenty on google to help.
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C-3PO

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Re: Voltage at end point?
« Reply #5 on: September 15, 2017, 02:47:48 PM »

Hi Brian,

Nice Atmel (ATMEGA16) chip and transistor switching.

You could duplicate this with our friend the Arduino

Board states that each output can switch max. current per channel 1A , in summary max. 5 A ( in summary I think you can take as in total for the whole board)

So 22 channels with max load 5 amp and no one channel more than 1 amp ( but there are 12 8 pin components which would suggest 24 channels)

Not quite sure I understand your original post but you can have multiple  LEDS per output so long as the overall current draw in max 1 amp per channel and 5 amp for the whole setup

I would be interested if you could see the component ID on the little DIL 8 pin components


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malcolmfrary

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Re: Voltage at end point?
« Reply #6 on: September 15, 2017, 03:38:53 PM »

I have 'x' amount of led's each voltage lowered by resistors in the positive side - down to 3v each. The negative side of the 'x' amount, lets say there are 4 to make things easy, go to a switching module.

You don't lower the voltage with LEDs, you restrict the current.  Any LED will act as its own voltage regulator, the early ones standardized at 1.9 volts, later ones you need to read the spec for, but white ones do regulate themselves at a higher voltage.  In a lot of circuits from yesteryear, an LED was used as a constant reference voltage that doubled up as an indicator to show that the circuit was active.  What voltage is seen across the LED depends on both the LED itself, whether it is on or off, and the circuit driving it.
From the drawing in the .pdf, if you have a bunch of current limit resistors connected to the supply rail each feeding one LED, and the other end of the LEDs commoned, and their outlet is not switched on, you get that supply voltage because there is zero current.  (Or supply less whatever the LEDs drop at that very low current).  If the outlet is switched on, you measure zero volts, at the other end of any of the LEDs (now lit up) you measure the LED characteristic voltage.



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Brian60

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Re: Voltage at end point?
« Reply #7 on: September 16, 2017, 10:18:23 AM »

Hi Brian,

Nice Atmel (ATMEGA16) chip and transistor switching.

You could duplicate this with our friend the Arduino

Board states that each output can switch max. current per channel 1A , in summary max. 5 A ( in summary I think you can take as in total for the whole board)

So 22 channels with max load 5 amp and no one channel more than 1 amp ( but there are 12 8 pin components which would suggest 24 channels)

Not quite sure I understand your original post but you can have multiple  LEDS per output so long as the overall current draw in max 1 amp per channel and 5 amp for the whole setup

I would be interested if you could see the component ID on the little DIL 8 pin components


C-3PO

Yes I know about the arduino aspect Jonathon. I have the code from the ship lighting subject on the arduino forum. I just wanted to make use of this board which when I bought it seemed to do everything I wanted. Its a good job I have an Uno and a Mega I'm rapidly running out of outputs!  {-) The uno is planned to manage 4 dc motors, 4 servo's and two steppers up to now, when I can get the code into a workable configuration so it all works together instead of in individual segments :embarrassed: without adding anything else to it. I just might move all that over to the Mega.

The numbers on the chips, and I can tell you this was so tiny I had to take it out in the sunlight, I had on a pair of 2 dioptre magnifying glasses and a handheld 5 dioptre glass and they were still barely legible. .....

I(a symbol here)R    PO29H
                              Y3M2
                              F7103

Hope that satisfies your curiosity :}

I think what I'll do is set it up on the bench with some led's attached and see how it goes. I always have the option of falling back to the arduino, but its not my first choice at the moment.

Thanks everyone for your input.

 
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