Relay only turns on

I tried the 5VDC rated relay with the new boltiot board. Thought with a HIGH state in digital write from the GPIO the relay behaves as it should, it shows the same behavior with the LOW state. This on the other hand, works as intended when the relay is connected to an arduino board or when the same logic is applied to an LED with either Arduino or boltiot.

Is there some specific setup to be taken into account while working with relays?

@ashishlijhara: Are you using a relay directly with the Bolt or are you using a relay module?

The Arduino supplies at best 50mA of current at 5V, while the Bolt supplies at best 12mA of current at 3.3v.
You have to take into consideration the activation power required by the relay. You relay probably requires more power to activate then the Bolt can supply, while Arduino may be able to supply that much power.
For a relay module, this consideration is not required, as it takes this power from the 5v supply, and only uses the Arduino or Bolt pins for signals.

I have the relay connected to the 5V terminal, yes, I do not have a multi mater and yes, a potential of 3.6V is required to activate the relay anything below 3.6 would turn it off and above 3.6V would turn it on.Sure, I also understand The two boards supply different current outputs.If that was the case, How would it activate on a digital write with my connection while supplying either of the states? This is what has got me thinking vinayak: Connections are Common and Normally Open. digitalWrite with HIGH or LOW does switch on the circuit.

Thanks for your reply.


Please confirm, are you using a relay module or a relay individually?
Are the terminals of the relay connected to GPIO and GND, or GPIO and 5V?

If you are using Bolt Module with a relay module, you have to connect the relay supply to 3.3v pin. Some modules will not work, if connected to 5v pin.

With a 5V rating, I was under the impression 5V connection would work.

@vinayak.joshi, thanks, I am using a relay module. Yes, you are correct, 3.3V works with the module.Although, the ‘HIGH’ state now switches the relay off and the ‘LOW’ state switches it on! Which of course does not happen when I am using an ESP8266 or arduino.

we can do in reverse as if connecting to 3.5 volts as it works and due to potential difference it happend

That’s what I did in the end. But now I have stopped using bolt all together. It was great fun to learn from it.

@ashishlijhara and @vinayak.joshi, so we have to connect 1 pin to gnd , 1 pin to 3.3 volt and the signal pin to GPIO pin(0-4) ? Am i right?