D2P: Using Analog output to switch a 12v LED

shaunb
Posts: 2
Joined: Wed Jan 06, 2021 11:39 am

D2P: Using Analog output to switch a 12v LED

Postby shaunb » Wed Jan 06, 2021 4:03 pm

I'll be installing my Dash2Pro in my Locost race car. I wish to use one of the analog outputs to control a 12v warning LED in the dash. The LED has a +12v feed and I've connected the LED -ve to Analog output 4, as per the bulb diagram in https://www.race-technology.com/wiki/in ... putDrivers. I set set up the trigger rule and when triggered the LED glows brightly as expected, however when not triggered the LED is still glowing faintly, so a small amount of current is obviously still flowing. Any ideas on what I need to stop this behaviour?

Switching via a relay works as expected, but I thought I would be able to sink the LED current (~30mA) directly.

Shaun.

shaunb
Posts: 2
Joined: Wed Jan 06, 2021 11:39 am

Re: D2P: Using Analog output to switch a 12v LED

Postby shaunb » Fri Jan 08, 2021 1:06 pm

I had a live chat with RT support yesterday. The issue is basically that D2P output goes low when activated, but just floats otherwise. When it was floating it was allowing a few mA of current to flow which was enough to faintly glow the LED, but not enough to light a bulb or keep a relay tripped. The solution is a 1k pull up resistor in parallel with the LED (i.e. between +12v and D2P output driver). Perhaps an update to the Wiki is needed to record this.

Shaun.


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