Inverting dimmer output

Hi,

I have a quick question on dimmer setup for a L5504AMP 0-10V analogue unit.

Basically the LEDs that I have required a PWM signal in order to dim and this is wired up to the L5504AMP unit correctly. The LEDs dim, but the wrong way. In other words a dim output of 99% results in the LEDs being almost off and a dim output of 1% results in the LEDs being fully on. I have talked to the manufacturers of the LED package (Lumascape) and they told me that they noticed the same problem, but were told by Clipsal that their system can handle the inverting of the output.

I've had a look through the CBus Toolkit software to see if I can invert the output of the L5504AMP unit, but I can't find anything.

Hope someone out there can help me???

Cheers,
Russ

 

The output of the L5504AMP cannot be inverted. Whoever answered that question from Clipsal either does not know the product or did not correctly understand the question being asked.

If you have a device in your system that has the logic engine, you can invert the output using logic (so in this sense the advice from Clipsal was correct). Read the level of your group, invert it and then re-transmit the level out on a new group address. The input and output units would have 2 separate group addresses, linked by logic.

 

A left field thought would be to use a 2 channel Bus Coupler with Remote LED capability. It would require some fiddling, but bear with me...

It has external LED connections. Pretty much any LED can be wired into the unit for showing group status and the LED will receive a fixed current of 10mA or thereabouts. You could fit a regular LED to these connections and then in parallel run a short wire (no more than 1m of cable) to the input of your LED driver.

The Bus Couplers were updated a few years ago to include the ability to set Scenes. This is not important. What is important is that at the same time the product gained the ability to dim it's external LEDs and it does this using PWM. It also gained the ability to have it's indicator status inverted, which can be configured in Toolkit.

None of this works if the signal the Lumascape unit is looking for is 0-10V as the bus coupler will only give you an 0-3V signal (depending on LED Vf), but it will be using PWM for the dimming and the signal can be inverted.

The logic solution is much cleaner and infinitely flexible, but the Bus Coupler solution might be an option (albeit long-winded with plenty of unknowns) if you don't have any units with the logic engine and the dollar jump to a PAC is a bit too far. If you can afford to put a PAC in, you'll find an infinite number of things to do with it, so it's definitely the recommended solution.

 

What about a modification to the drivers. I have stumbled onto a thing called an inverter.

http://en.wikipedia.org/wiki/Inverter_(logic_gate)

These types of circuits are about as old as the transistor.

 

Thanks guys for the quick reply. Much appreciated.

I've got a Wiser fitted so the logic engine option is the best and have just tried it out with success

Would've liked to have a go at the transistor solution too, but unfortunately it would require a Vcc to run properly and (from what I can tell) the L5504AMP doesn't give out a constant 10v output, just the variable output

Yep, first thing I tried was reversing the polarity, but no joy. The PWM generator is too clever (or too dumb) to fall for that one

Thanks again everyone
Russ