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Hi im fairly new to Arduino and im working on an aquarium controller project. At present i have made a temperature probe which appears to be reading quite accuratly. What i want to happen is this temperature probe to turn on and off the Heater. I have bought a tinkerkit relay (+5v switches to 240v) as i thought it would be easier to interface with the Arduino. which has the folling pins:-

-
+
middle pin which isnt labelled.

I have connected the 0 from my Arduino to -
and +5v from Arduino to +

My question is, can i connect the Digital output straight to the middle pin or do i need to go through a resistor?

I have checked the PDF files that i can find on the tinkerkit relay but they dont seem to provide and suggested circuits.

Thanks

Dan


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If that is a mechanical relay, then the Arduino probably doesn't have enough output current on a digital pin to drive the coil of the relay. You need to buffer the output with a transistor. I recommend a BS170 (which is a MOSFET). The full circuit will look like

digital pin -> 220 Ohm resistor -> Gate of MOSFET

+5V -> relay coil -> Drain of MOSFET

Source of MOSFET -> GND


However, it looks from the Tinker relay that it actually contains this buffer already. If that is the case, then you should hook it up according to the "tinker" connection cabling, which I have no idea what it is. My guess is it might be:
Arduino -> Relay
+5V -> "+" pin
digital pin -> unlabeled
GND -> "-" pin

With correct hookups, the relay should light green when the Arduino has power, and yellow when it's actually activated, according to the description I found on Google.
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The middle pin on the Tinkerkit connector is the signal pin, that would hook up to the digital pin that you want to use on the Arduino.  The Tinkerkit relay is a module that has the necessary transistor for switching it, as well as status LED's.  Just hook the + and - pins up to 5V and ground, and the middle pin the digital output pin that you want to use.
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The middle pin on the Tinkerkit connector is the signal pin, that would hook up to the digital pin that you want to use on the Arduino.  The Tinkerkit relay is a module that has the necessary transistor for switching it, as well as status LED's.  Just hook the + and - pins up to 5V and ground, and the middle pin the digital output pin that you want to use.

Ok thanks, so i dont need to put a resistor in series with the digital output pin?
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Also i am looking to drive up to 5 of these relay modules. will the 5v supply from the Arduino be ok? or should i use an external 5v supply?

Thanks

Dan
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I am looking to drive 300 miles. Will the fuel in my tank be sufficient?
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