LED-Wiz on 12V circuit

[Green Giant]

So I know the LED-Wiz is only designed to handle a 0-5V signal, but I have been having a dilemma with wanting to power some 0-12V special LEDs.

I wanted to run my primary idea across you guys.

Basically I wanted to run a 0-12V RGB full color spectrum with an LED_Wiz signal as easily as possible.  My plan is to use an opto-isolator simple circuit to relate the 0-5V signal into a 0-12V signal.  The system would derive the 5V and 12V signals from the computer power supply.

an example circuit can be found here:  http://ecelab.com/opto-level-shift.htm

Do you guys forsee any problems running this circuit?

[drventure]

I don't believe you have to do this.

The LEDWiz has a connector for "External power". Actually, it's got several "banks" for external power.

The external power can be 5vdc, or 12vdc, or whatever.

The only restriction, I believe, is that, let's say you hook Bank 1 up to 12vdc, then all the LED's connected to bank 1 need to be wired for 12vdc.

Check the LEDWiz docs for details though. You'll want to read the stuff on the BANKS in particular.

The only normal reason for optoisolators or relays if if you're driving solenoids, IL Wire, or normal incandescent lamps, etc.

But you can also check directly with the LEDWiz guys, they're very helpful.

[Green Giant]

I don't believe you have to do this.

The LEDWiz has a connector for "External power". Actually, it's got several "banks" for external power.

The external power can be 5vdc, or 12vdc, or whatever.

The only restriction, I believe, is that, let's say you hook Bank 1 up to 12vdc, then all the LED's connected to bank 1 need to be wired for 12vdc.

Check the LEDWiz docs for details though. You'll want to read the stuff on the BANKS in particular.

The only normal reason for optoisolators or relays if if you're driving solenoids, IL Wire, or normal incandescent lamps, etc.

But you can also check directly with the LEDWiz guys, they're very helpful.

I probably should have referenced this earlier, but my LED-Wiz's were bought back in 2006 or 2007.  This optional bank1 and bank 2 thing didn't exist.

I just saw on another thread some info about this which I had no idea exists, but I am pretty sure my LED-Wiz's only support 5V across all the ports.

[drventure]

Ah. Well, if the bank stuff isn't there, yeah, it gets trickier. I'll take another look at your circuit

[drventure]

Yep, that circuit should do the trick.

Really, you could use an opto-isolator or a solid state relay (SSR), but then, a lot of SSRs actually use opto-isolators internally...

What sucks is that'll be a bit of wiring..

[Green Giant]

Yep, that circuit should do the trick.

Really, you could use an opto-isolator or a solid state relay (SSR), but then, a lot of SSRs actually use opto-isolators internally...

What sucks is that'll be a bit of wiring..

Thanks.  I am not to worried about the wiring cause this will be for just 3 RGB signals so 9 little circuits total.

Almost all my signals are for my electric ice buttons, but I think I had a few extra ports that can be utilized for a side project.

[yaksplat]

Given the choice, I'd just buy a new LED wiz and sell off the old one, or save it for 5V led's.

[MonMotha]

I was of the impression that all LED-Wiz outputs are sink-only and "high voltage" tolerant.  You can hook them up to any voltage you want, subject to a maximum (probably 25V or greater) as long as the ground is referenced to the same ground as the LED-Wiz.  This is a very typical arrangement.  The "bank voltage select" is only for hooking up the on-board freewheeling diodes, which are not necessary for LED loads.

If indeed your LED-Wiz is only 5V compliant (I very much doubt it), you can actually get by with just a transistor rather than needing an optoisolator.  The circuit you posted above probably doesn't do what you want here, anyway.

I'd ask RandyT.  I suspect this is far simpler than you are making it to be.

[Green Giant]

I was of the impression that all LED-Wiz outputs are sink-only and "high voltage" tolerant.  You can hook them up to any voltage you want, subject to a maximum (probably 25V or greater) as long as the ground is referenced to the same ground as the LED-Wiz.  This is a very typical arrangement.  The "bank voltage select" is only for hooking up the on-board freewheeling diodes, which are not necessary for LED loads.

If indeed your LED-Wiz is only 5V compliant (I very much doubt it), you can actually get by with just a transistor rather than needing an optoisolator.  The circuit you posted above probably doesn't do what you want here, anyway.

I'd ask RandyT.  I suspect this is far simpler than you are making it to be.

I am only trying to get 3 inputs off the board, maybe 9, to cover 0-12V while the rest will be putting out a 0-5V signal.

Even if my LED-wiz's could handle a 12V signal, I can't send that much juice to my electric ice buttons.

A transistor would only work for on-off, but I really want to run a RGB attract mode with these separate 12V led lights; so I need to handle 0-48 PWM intensity.

Do you have any suggestions for a 0-12V signal from a 0-5V controlling signal?

[MonMotha]

As the LED-Wiz is sink only, you should be able to mix voltages within a bank.  The LED-Wiz doesn't actually provide a "5V signal", it just effectively turns on/off a switch to ground to provide or interrupt a path for electricity to flow from whatever voltage supply you select back to ground.  Now, if the rev 1 LED-Wiz hooks the bank common up to 5V internally, you've got a problem unfortunately.  I'd really recommend just trading out for a new one, if that's the case, since all your problems will magically go away, and you can get by without a single external component, then.

Please just ask Randy about this.  The documentation on the website for the old model doesn't answer a very important question for this usage.  It's somewhat likely that you have no problem at all, here.

If you must use what you have, and what you have is really limited to 5V, by far the easiest solution is a solid state relay.  You can get smallish ones that'll do what you want, here.

There are some other options that may be cheaper if you're willing to string a few components together and/or don't need a ton of current handling per channel.  Basically, take the original optoioslated circuit you posted and remove Rout.  In its place, substitute your LED load, including appropriate resistor for 12V.  Rin should be ~220 ohms. Use something like an LTV-815 for the optoisolator.  That'll get you about 80mA per channel with only 2 extra parts per channel.  If you need more than 80mA per channel, another resistor and a suitably sized transistor will get you well more than the LED-Wiz could originally handle, if you want.

[RandyT]

Maybe I can clear this up.  The older LED-Wiz was not able to mix voltages, as it shared a common connection to a diode in each of the driver chips.  If the +5v line was not connected to the board, and the USB 5v jumper was not used, any voltage up to 50v could be used. 

The current version has a separate connection (Bank Voltage terminals) to the internal diodes for each driver chip.  These are useful in protecting the drivers when inductive or loads are attached directly.  While it is probably possible to drive multiple voltages on any one bank when the Bank Voltage terminals are unused, we suggest using those connections and limiting one voltage level per output bank.

RandyT