solid state relay - SSR LED light on even when ESP8266 pin is off

I'm powering a heater with an SSR and esp8266 nodemcu module. I've found out that I need a higher voltage to effectively trigger it than what the nodemcu can put out on a digital pin (from previous post SSR ticking when controlling heater).

I have added a transister and diode combo into my network (based on https://electronics.stackexchange.com/a/220504/137437) which allows the 3.3v from the esp8266 to trigger 5v:

This works but when the digital output from the nodemcu is off, an LED on the the SSR still maintains a very slight glow.

If I power the nodemcu from a different wall wart that is plugged into an external wall socket (see diagram below) the led on the SSR is off when the digital output is off.

Is there some feedback or something that is making the SSR Led be on when there is no power to the P1 pin? I have tried testing the voltage across the SSR low voltage input but only have a rudimentary voltage tester and when I try it doesn't read anything and the led goes off.. Or is my wall wart used in the first diagram just dodgy?

Answer

One of two solutions might help you.

1. Add a 10k resistor from the Port pin to ground.


2. Add a 1k resistor directly across the SSR low voltage input pins.