I bought today this kit from All Electronics in Los Angeles. I built it and now hope with little modification to be able to use my Arduino Uno Rev 3 to control the 4 relays.
The voltage rating is listed as follows:
- Max. load: 240V AC / 3A resistive
- 9V DC / 300 mA power supply
- Is controlled by a open collector output (9V/15 mA)
The manual that has this information can be found in the attachments.
Can an Arduino Uno Rev 3 output this voltage, or do I need some other parts?
Need another component - can be a simple NPN transistor like 2N2222 with 270 ohm resistor.
Arduino to resistor to transistor base.
Emitter to Ground
Collector to the control pin.
Arduino hi out turns on the transistor, the colllector goes low, turns on the PNP transistor and the relay changes state.
Thanks! I will try that tomorrow after I go get the parts.
Ok, I have the parts and have been looking at schematics and other posts about this kit, but I don't want to risk blowing the Arduino, the kit up and possibly my eyebrows. Is it possible that I could get a schematic of CrossRoads post and possibly a explanation of what page in the playground to take a look at? Any help is better than nothing. Thanks!
digitalWrite a High to the Arduino pin to make the relay change connections.
Then Low to go back.
Thanks for putting up with my questions. I believe I understand the basic idea of the whole circuit. By the way, is their any program that allows me to test a schematic to see if it will operate properly? I end up a lot of the time with more unused or fried parts than working ones. I just need some way of making a circuit and testing it without actually spending money. I understand some of the terms in a schematic, but am more used to seeing "clipart" schematics. I am learning though.
You can look at things like LSpice, I think that's the freeware version, for simulations.
This is simple enough tho, a 2n2222 transistor can handle the 9mA and 12V from the relay coil.
270 ohm resistor between arduino and transistor base.
Hi, attatched is my current setup. What I want to do is be able to short the green 9v gnd wire with any of the 4 signal pins by using the arduino as a "virtual" relay/button switch. Can I use the blink program even though the green wire is 9v? Is there a simple resister that I only need 1 attached to the green wire to reduce the voltage.
See Figure 9, page 7 of the assembly manual.
The Green wire in your picture connects to Arduino ground.
The Relay control pins are pulled up to 9V, the red wire.
What ever you connect has to be able to take 9V. Arduino outputs can't do that.
You need transistors like in Reply #4, or a part line ULN2003 that can handle higher voltages.
If the bases of T1-T4 aren't allowed to go 9V, than they will be partly turned at say 5v, and the relays will likely behave erratically.
Do I need a transistor for each pin or is their some way I can use just one, I only have one in by parts bin right now.
You can use one if you want all the relays to turn on together.