Two projects: Need help choosing hardware

Hi everyone! I'm new so be gentle please. I'm looking to create two projects for fun using arduino. I just bought the starter pack and am working my way through the various projects in them. I have come up with two myself I would like to accomplish, but need guidance with hardware slection. (Coding will come later).

Project 1: I'd like to activate lights by setting up switches in series. I would like to dress up knife switches to use reed switches instead (for safety reasons). Placing a magnet in the handle and a reed switch either at the top or bottom of the base, the knife switches will need to be placed in a specific up or down sequence to turn on the lights. I'd like 5 or 6 of those. My problem here from what I can tell is that the lights use a much higher voltage than the reed switches usually can handle. Is this a case where I would use a mosfet? How would I complete the circuit using the reed switches and turn on the lights? The lights by the way would be used to light up a whole room, so no small LEDs. One idea I had was to program the Arduino to send a signal to a relay wirelessly, but then how would I provide power to the lights if they have to be plugged into an outlet?

Project 2: This may be similar to the previous project. I want to have candles placed into a candelabra and light up using an LED. This part I'm pretty sure I can do using a reed switch, 9v battery, and placing a magnet in the candelabra. I then want people to blow out the candle. I'd place a microphone near the LED to pick up them blowing it out. The part I think I need help on is how to send a signal wirelessly to a lock that would open up a door. I'd want the candles to be blown out in a specific sequence and the receiver to determine if the sequence is correct. That bit is coding which I can figure out later, right now I'm more interested in what equipment I would need to make something like that happen.

Let me know if more information is needed. Apologies if so, I'm still figuring all this out. I appreciate the help!

Update Just found this great video about controlling high voltage using a relay :smiley:

Project 1. You are confusing solving your problem using an electrical circuit with solving it using microprocessor. Using the microprocessor you attach the switches as inputs to the Arduino. The Arduino then 'knows' which switchas are opened or closed, it then operates an output ot outputs tocontrol the lights. So the power for the lights is not going through the switches. To control the lights you might use relays operated by the Arduino either by wiring or WiFi - it really depends on distances, layout, number of lights etc.

Project 2. You probably want to hide the Arduino and a battery supply in the candelarabra and use wirless to communicate to another device/s to operate a door lock etc.

Stick with working through the starter kits first.

Please post photos here. Your external link doesn't work, external hosts blocks it.

Tyler314:
My problem here from what I can tell is that the lights use a much higher voltage than the reed switches usually can handle. Is this a case where I would use a mosfet?

Depends on the voltage, and AC or DC.
If DC a MOSFET may work. A relay may be your best bet.

Arduinos can read reed switches easily. Connect between pin and GND, set pinMode to INPUT_PULLUP to activate the internal pull-up resistor, and the moment the switch is activated (and closes) it reads LOW. When the correct sequence has been detected it can activate an output, which in turn switches your light.

ardly:
Project 1. You are confusing solving your problem using an electrical circuit with solving it using microprocessor. Using the microprocessor you attach the switches as inputs to the Arduino. The Arduino then 'knows' which switchas are opened or closed, it then operates an output ot outputs tocontrol the lights. So the power for the lights is not going through the switches. To control the lights you might use relays operated by the Arduino either by wiring or WiFi - it really depends on distances, layout, number of lights etc.

Project 2. You probably want to hide the Arduino and a battery supply in the candelarabra and use wirless to communicate to another device/s to operate a door lock etc.

Stick with working through the starter kits first.

ardly:
Project 1. You are confusing solving your problem using an electrical circuit with solving it using microprocessor. Using the microprocessor you attach the switches as inputs to the Arduino. The Arduino then 'knows' which switchas are opened or closed, it then operates an output ot outputs tocontrol the lights. So the power for the lights is not going through the switches. To control the lights you might use relays operated by the Arduino either by wiring or WiFi - it really depends on distances, layout, number of lights etc.

Project 2. You probably want to hide the Arduino and a battery supply in the candelarabra and use wirless to communicate to another device/s to operate a door lock etc.

Stick with working through the starter kits first.

I'm realizing now that the switches are separate from the lights and that the arduino will control a relay to switch on the lights which have their own power source. I also found a power relay outlet which the arduino can connect into easily. I thought about hooking up my own relay into a power cord, but the outlet power relay module seems simpler and safer, at least for my novice skills.

I don't think I explained well enough, so I apologize. The candles won't be attached to the candelabra to begin with. I imagine attaching a transmitter to the microphone which will send a signal to an arduino and read it as an input. If I put an arduino inside each candle, that gives me the means to turn on the LED and microphone as soon as they're placed and once the candle is blown out it could send a signal to another arduino attached to a lock yes?

I'm having a ton of fun working my way through these projects as well and I appreciate the responses to my questions :slight_smile:

wvmarle:
Please post photos here. Your external link doesn't work, external hosts blocks it.

Woops didn't know about the external host blocks.

Tyler314:
....
I don't think I explained well enough, so I apologize. The candles won't be attached to the candelabra to begin with. I imagine attaching a transmitter to the microphone which will send a signal to an arduino and read it as an input. If I put an arduino inside each candle, that gives me the means to turn on the LED and microphone as soon as they're placed and once the candle is blown out it could send a signal to another arduino attached to a lock yes?
...

That really does not make sense. You would not fit an Arduino into each candle.

You might fit one Arduino into the light fitting and then use it to monitor all the candles in the candelabra . Also using microphones to detect a candle being blown might be tricky. If these are real candles then hiding light sensitive resistors in the light fitting so that they can "see" when candles are blown out might be much simpler (you would probably want low ambient lighting and no other strong light sources in the room). The single Arduino in the light fitting could communicate by WiFi with another to operate doors etc.

Tyler314:
Woops didn't know about the external host blocks.

It is not the forum, it is that specific host that blocks hyperlinks so we can't see it. Just try to follow your own link. Anyway it's better to post images in this forum, so we're not relying on external hosts to remain up and not change URLs and so.

ardly:
That really does not make sense. You would not fit an Arduino into each candle.

You might fit one Arduino into the light fitting and then use it to monitor all the candles in the candelabra . Also using microphones to detect a candle being blown might be tricky. If these are real candles then hiding light sensitive resistors in the light fitting so that they can "see" when candles are blown out might be much simpler (you would probably want low ambient lighting and no other strong light sources in the room). The single Arduino in the light fitting could communicate by WiFi with another to operate doors etc.

I mean they already have candles that turn on or off when you blow on them. Couldn't I take one of those and modify it to turn on when placed in a specific location then send a signal when blown out? If I can get them to send a signal to one arduino which controls the lock that would be perfect!

Maybe, maybe not… Depends on the candle and the internal construction!

My money is on the second, though. Usually it’s a highly integrated and specialised piece of electronics that can not be modified.

wvmarle:
Maybe, maybe not... Depends on the candle and the internal construction!

My money is on the second, though. Usually it's a highly integrated and specialised piece of electronics that can not be modified.

I see. I'll research it some more. I appreciate your help!