I need help choosing the right reed switch.

Sulla

Sulla

Sr Member
RPF PREMIUM MEMBER
I am building a wall mounted Star Trek replicator prop. **edt**(note - IE will not properly open trekpropzone. You will need firefox or similar.)**edit**

It will have a ‘busy box’ of circuitry and components inside visible when access panels, held on with small rare-earth magnets, are removed. Taking a cue from the Tricorder, I wanted to use a reed switch with those magnets to activate the inner lights.

I will need two reed switches. One is for the smaller LED electronics powered by 9V or 12V batteries (not sure which way I’ll be going: I haven’t worked out the resistors with ohms law yet) and I will be using the smaller NO (normally open) glass reed switches like these:

BbS88EwmkKGrHqQH-DYEqu0jHCBKvVUJGoQ.jpg



But I will also have some 120V AC lighting in there plugged into a normal US outlet. The small glass reed switches cannot handle that power. I thought of using some larger reed/magnetic switches like the ones you see in house alarms mounted to doors and windows, but all I can find so far ar NC (normally closed.)

Any advice?
 
Thanks for the tip. I was just hoping to throw a switch into the circuit between the power and the lights. I originally intended to use a simple rocker switch, but I thought it'd bee cooler to have the lights just 'pop-on' when you open the thing up.

I was also originally just going to have one switch turn everything on whether the box was closed or not, but I hate dealing with light leakage and was hoping for a simple N.O. reed switch to do the deed for me and save me some light leakage and relays.

I am also trying to avoid N.O. pressure switches too.
 
Not sure why you couldn't use a window reed switch and just replace the brighter 120V AC lights you'd need to plug in, that take considerably more juice to run, with ultra bright leds. I have seen 9 volt ultra bright white leds that could light the Statue of Liberty torch. Ok, an exageration, just her pedestal.
 
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I have 2 very nice LED lighting elements -store bought and ready to go. One will light the dispensing alcove and will be seen externally. This one will be turned on and of by a hidden push button switch. The other is an LED lighting element that will be on the inside and needs to be activated only when the covering panel is removed hopefully by a strong enough reed switch. They both plug into the wall and both take 120V AC.

Inside the busy box of circuitry I am going to seed the whole thing with a random smattering of blue and white LEDs for effect (those are the colors I have laying around.) They will be running off batteries with the smaller glass reed switch for activation.

Maybe I'll just run the inside lights as LEDs to a battery source and save that other 120V lighting element for another project...
 
OK, if I am using low voltage LEDs (like 3.2V~3.8V) and a battery source, will the small glass reed switches I picked out work? The only description they give is:

“These are appropriate for low level signals - NOT AC switching. The auctions is for 20 NOS, axial glass package with leads.”

I will be using them between my LEDs and 9V (or no more than 12V) power source.
 
It would appear I actually need Normally Closed reed switches. As I have come to understand it N.C. reed switches require a magnet to activate the reed when the panel is closed. This activation opens the contacts of the reed, providing a break in the circuit.

So readily available N.C. 120v alarm system reed switches are an option.

How about a reed switch with these specs?
Contact Type: N.C. (normally closed) contacts are closed with magnet engaged.
Contact Rating: 10VA
Max. Carry Current: 1.0A
Max. Switching Current: 0.4A
Breakdown Voltage: 200V DC
Contact Resistance: 100m Ohm. Max.
Magnet Type: Anisotropic Ferrite
Operating Gap: 3/4"
Operating Temp. Range: 32F to 120F (0C to 49C)
 
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^ Would you be using these reed switches to operate your 120V electronics or your battery-powered electronics?

The best way to see if the reed switches you've selected will work is to spec out the total current draw or power consumption of your finished circuit and ensure it does not exceed the switch's ratings. Without that info, I doubt anyone here can give you a hard answer.
 
tim said:
^ Would you be using these reed switches to operate your 120V electronics or your battery-powered electronics?
Click to expand...
There will be two reed switches. One for the battery powere stuff, the other hopefully for the 120V stuff. Though I am thinking of forgoing the 120V component since this is turning out to be more trouble than it's worth.

The best way to see if the reed switches you've selected will work is to spec out the total current draw or power consumption of your finished circuit and ensure it does not exceed the switch's ratings. Without that info, I doubt anyone here can give you a hard answer.
Click to expand...
I am not entirely sure how to do this. But I'll give it a go.
 
Sulla said:
There will be two reed switches. One for the battery powere stuff, the other hopefully for the 120V stuff. Though I am thinking of forgoing the 120V component since this is turning out to be more trouble than it's worth.
Click to expand...
For the battery-powered stuff, the cited reed switch should be fine.


I am not entirely sure how to do this. But I'll give it a go.
Click to expand...
If you're not sure how to determine the total current draw and power consumption of the 120 V components, I'd advise having someone who does work on the design with you. You want to ensure adequate safety with anything plugged into the wall.
 
tim said:
For the battery-powered stuff, the cited reed switch should be fine.


If you're not sure how to determine the total current draw and power consumption of the 120 V components, I'd advise having someone who does work on the design with you. You want to ensure adequate safety with anything plugged into the wall.
Click to expand...

Agreed, and thanks again for all your advice. I picked up some blinker lights from Hobby Lobby last night and have some small LEDs that I can all wire up to small battery power sources on the sited reed switches. I've asked for a friend's help on the other lighting element but I am still thinking of scrapping it.
 
Look for diagrams of circuits using triacs, they should handle the load and you can trigger them with the reed switches.
 
That's a nice little switch, but it's NO. I need NC.
How about these? evilbay # 280394795428

The size is not that big a factor for me.

Looks like a simple SPST though it does not say...
Contact Type: N.C. (normally closed) contacts are closed with magnet engaged.
Contact Rating: 10VA
Max. Carry Current: 1.0A
Max. Switching Current: 0.4A
Breakdown Voltage: 200V DC
Contact Resistance: 100m Ohm. Max.
Magnet Type: Anisotropic Ferrite
Operating Gap: 3/4"
Operating Temp. Range: 32F to 120F (0C to 49C)
 
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^ Once again, do you have a final design worked out? It'll be easier to spec components with the proper ratings if you have the circuits diagrammed. If you are using only battery-powered LED lighting, though, the switches should be fine.
 
tim said:
^ Once again, do you have a final design worked out? It'll be easier to spec components with the proper ratings if you have the circuits diagrammed. If you are using only battery-powered LED lighting, though, the switches should be fine.
Click to expand...

I am going with only battery powered LEDs now. Maybe a single PC fan on it's own 12V circuit too... not sure on that yet. :lol :confused
 
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