Help me learn circuitry!

[wow.such.chris]

Some day down the road I'd like to make my own muti-channel, controllable LED light, but with no circuitry experience I think I've found a very simple project to get me introduced. I'm sick of overflowing my 5 gallon RODI bucket...

 

I'd like to make an alarm that I can attach to a 5 gallon bucket which will sound and light an led when a float switch is closed. I'd like it to run on a 9 volt and have an on/off switch for when it is stored to prevent it from going off if the float switch is tripped.

 

 

Can i just throw a switch in this design put it on some breadboard and be set? I would think it can't be that simple. Are the boxes and dots just connections? If anyone has any place they think I should start reading please let me know.

 

 

[spinycheek]

That looks like it would work to me. You could also attach a little solenoid valve to close when the alarm/light goes off.

 

http://www.adafruit.com/products/997

[wow.such.chris]

That looks like it would work to me. You could also attach a little solenoid valve to close when the alarm/light goes off.

 

http://www.adafruit.com/products/997

 

Thanks for replying!

 

I've always wondered what happens when you close the outlet of my little counter top rodi unit for long periods. I've done it for short spurts but I worry the buildup in pressure will cause problems.

Any suggestion on what sort of wire to use? Or where to order any of this stuff?

[evilc66]

Or just make a bracket to hold a float valve on the side of your bucket so the RODI filter shuts off when its full. Pretty foolproof at that point. Most RODI systems have an automatic shutoff valve that activates when the backpressure on the output line increases. Blocking the output won't hurt anything.

 

If you do want to do things electronically, there are a few things to consider:

1. Don't use a 9v battery. They have pitifully low capacity and will drain quickly. You would be better off using a low voltage (5-12v) DC power supply.
2. Whatever light/buzzer/solenoid you use, you will have to make sure that it's rated for the voltages that you end up using. If you go with a 5v power supply (common cell phone chargers, etc...), then make sure the lamp/buzzer/solenoid is designed to work with 5v DC.
3. If you do decide to use a solenoid valve (this is one primary reason for not using a 9v battery, as it will drain it in short order), you need to get one that has no metals in the body. Those are sadly not cheap.
4. Wire size depends on how much current is being drawn. Most small lamps and buzzers won't draw much current, so small wire sizes like 24-20awg will be fine. A solenoid will draw a lot more current, so that may require larger wires (18awg most likely)
5. Use stranded wire, not solid core. It's more flexible and will not fatigue/break as quickly due to bending/movement.
6. Do not use wire nuts for any connection. They aren't meant for stranded wire, and certainly not super small gauges. Solder it or crimp it. Those are the only two reliable means for connection
7. Any exposed wire near water will corrode. Use shrink tube where possible to protect solder/crimp joints.

 

As for where to get this stuff, there are tons of options. Ebay is one, but it's a bit of a pain to get everything you need from one source. Surplus electronics places like MPJA or All Electronics are good, as they have parts cheaper than most larger electronics wholesale places like Digikey and Mouser, and usually have oddball stuff (new old stock, equipment pulls, etc...) that the big boys won't, and are great for projects.

[spinycheek]

You can valve the front/intake too, so no back pressure issues. I use Adafruit, Sparkfun and Amazon for almost every electronic thing I buy. Wire depends on your needs, how much voltage, amperage and distance you are using. I would think 16 gauge is plenty for your needs.