ESP8266 Community Forum

- Thu Mar 17, 2016 10:05 pm #43456 Hi,

I've etched a PCB for a project that involves using a g3mb-202p Solid Relay driven by a NodeMCU 1.0 running Arduino Code.

The g3mb-202p was intended to provide 12vDC to an Electronic Door Strike.

Upon initial testing, with a multimeter connected to the 12vDC out (from the relay) it seemed to work fine:
~0v when the ESP set the Relay to open
+12vDC when the ESP set the relay to closed

When connected to the load (The 12v door-strike) the strike does not activate and the output of the relay shows ~0v

I've read that the g3mb-202p is only intended for switching AC loads. Howcome I see the desired results with a multimeter and not when using the actual load?

Give that I've already Etched the PCBs, is there any way I can get this relay working with my 12vDC load?
Alternatively, is there any other DC-compatible relay that has the same footprint/pinout?

Hopefully someone can help me out or provide some clarification.

Thanks in advance!

Simplified schematic (Removed MFRC522, LEDs, Buzzers, etc to get message across simply) below:
(Corrected error in image that Pablo2048 pointed out)

Last edited by markusonfire on Fri Mar 18, 2016 6:54 am, edited 1 time in total.

- Thu Mar 17, 2016 11:01 pm #43459 The SSR you have chosen has a triac output with built-in zero-cross circiut. This means it cannot be used to switch DC loads.

I suggest you either replace the SSR with a simple transistor and optionally an additional optocoupler if you really need to isolate the load. My preference would be a mosfet (p-FET if you want high-side switching) for the transistor, but a BJT darlington transistor would do as well.
Alternatively you could use a SSR capable of switching DC loads (with a mosfet output stage), but that will probably cost more than a simple transistor and optocoupler.

Also be aware, that the button on GPIO0 will cause the ESP to enter firmware flash mode when pressed during power-up.

- Fri Mar 18, 2016 1:07 am #43467

The SSR you have chosen has a triac output with built-in zero-cross circiut. This means it cannot be used to switch DC loads.

I suggest you either replace the SSR with a simple transistor and optionally an additional optocoupler if you really need to isolate the load. My preference would be a mosfet (p-FET if you want high-side switching) for the transistor, but a BJT darlington transistor would do as well.
Alternatively you could use a SSR capable of switching DC loads (with a mosfet output stage), but that will probably cost more than a simple transistor and optocoupler.

Also be aware, that the button on GPIO0 will cause the ESP to enter firmware flash mode when pressed during power-up.

Thanks for that feedback Lethe!

Could you help me understand the following:

...I suggest you either replace the SSR with a simple transistor and optionally an additional optocoupler..

So a transistor can be used instead of a relay?
Would the transistor and optocoupler be in addition to the existing 2n2222 transistor?
Could you suggest what spec transistor/optocoupler to use and how they would be wiring (Perhaps edit my schematic?)
In the mean time, I'l read-up on the above recommendations you've made to gain a better understanding.

...Also be aware, that the button on GPIO0 will cause the ESP to enter firmware flash mode when pressed during power-up....

Thanks, I'm aware that this could be the case, but unfortunately all "non-special" GPIO pins are in use by other components (RFID reader, RGB leds, Piezo buzzers)

Thanks again!

- Fri Mar 18, 2016 1:17 am #43468 To Markusonfire - check Your schematic please (emitter of NPN transistor connected to 3V3 instead of GND and so on...)