Robo-Tank DIY Aquarium Controller Forum
ViperSpectra - Printable Version

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ViperSpectra - SyberSects - 12-26-2021

I'm about to start working on getting my ViperSpectra lights working with Robo tank and just wanted your opinion to make sure I'm doing this correctly.

The black box on these lights has 4 wires that goto the controller board/display. These are..
  • Purple on/off
  • Brown +12V
  • Blue PWM
  • Grey Ground
The only meter i have is from work and doesn't really read lower voltages.. no decimals. So Purple on/off i showed 3V while lights are on and 0 while off. Brown Showed 8V while off and 12V while on. Blue showed varied from 0-3V depending on brightness selected. and.. Grey.. Ground.

My current plan is to ignore the +12V as it just powers the control board. wire the ground. the PWM and the on/off.

PWM / Analog Port 1 would turn light fixture channel 1 on. Port 2 would control PWM. Port 3 would turn channel 2 on and 4 would control PWM.. at this rate i'd run out of ports after 2 fixtures and I have 3.

Would it be better then.. or would it be to much current? to run lets say port 1 turns channel 1 for all 3 fixtures on. port 2 turns channel 2 for all 3 fixtures on. then use the remaining 6 ports to control the PWM of each channel per fixture? or maybe combine those into only 2 more ports as well?

and would this entire setup even work properly?


RE: ViperSpectra - Rob F - 12-26-2021

Only 0-3v (guessing it's 3.3v) on Blue PWM isn't good. The signal from controller is 0-5v. Something like a logic level converter or using a couple resistors to create a voltage divider would be required. Other than this I think your plan should work.

If you have some 4.7k and 9.1k resistors that will drop 5v to 3.3v. You can replace the 9.1k with a 10k as it's more popular, that would give about 3.4v out which would be safe.

Here's a voltage divider calculator showing how they connect, R1 is 4700 ohm and R2 is 9100 or 10000 ohm.

https://www.digikey.ca/en/resources/conversion-calculators/conversion-calculator-voltage-divider

Just a guess but I think the current required on the Purple on/off 3v will be low just like the signals so you shouldn't have a problem connecting multiple to one pin. You can connect multiple light signals to a single channel.

If it turns out you need Brown +12 you could use a DC port for that but I agree it's probably not needed.


RE: ViperSpectra - SyberSects - 12-27-2021

Could I, until i rig up these resistors or what not, just meter out the pwm. figure out what setting is outputting about 3.3v and then never go above that?


RE: ViperSpectra - Rob F - 12-27-2021

You could do that but be careful. Only takes once to do possible damage.