# Reed switch and LED strip

#### Gonzo78

Joined May 2, 2016
3

#### takao21203

Joined Apr 28, 2012
3,702
you should buy a DMM and learn how to use it.

In such a case you need to measure current.
If it is far below the 0.5A specified, yes, you can use it.

But if you approach max. current its not uncommon for contacts to stick together.
Mostly with transformers and motors though.

#### Tonyr1084

Joined Sep 24, 2015
7,454
9,6 watts divided by 12 volts equals 0.8 amps (800 mA). Your reed switch (if it's a reed switch) is rated for 0.5 amps (500 mA). Unfortunately I don't know what the 9.6w/5M (the 5M part) means. I would suspect that if you try to use the reed switch it'll likely fail.

Now, the lights you wish to use - they are powered from a power supply that converts line voltage (120 VAC) to 12 volts (DC). If your plan is to leave the power supply running and switch the lights on and off via the magnetic switch then you're going to discover you're wasting a lot of electricity. If this were my application I'd seek to switch the power supply itself ON and OFF, not the output of the power supply.

Again, unfortunately your switch is rated for not more than 100 volts. 120 volts could arc internally and could potentially lead to a fire.

If we knew a little more about the application of your project along with the specs for the power supply IN and OUT, as well as the requirements of the LED Strip - then we may be able to recommend something better suited to your purpose.

OK, I think I figured out the "5M". I think it's FIVE METERS. so that would be 9.6 watts at 5 meters length.. That would be 1.9 watts at 1M (or 1.9/M). 1.9 watts (lets call it 2 watts) at 12 volts equals 167 mA (0.166666 amps) Fortunately that falls within the specs of the switch.

Years ago I installed burglar alarms. We used a switch that had a couple contacts in it. A magnet pulled the plunger away from the contacts, thus OPENING the circuit. When a door with a magnet was present the switch was held open. But when you opened the door (took the magnet away) the plunger fell to its normally closed position, thus, activating the alarm. They were not the same as the reed switches we used, so I'm wondering if the switch you're talking about is a mechanical plunger contact sort of switch and NOT a reed switch. Regardless - I think the switch will work for the short run you mentioned you wanted.

You said you wanted 12 LED's. 600 LED's in 5 meters - that's 120 LED's per meter. 12 LED's would be 1/10th that (or 100 cm). (0.1M). Yeah, it's looking like your project will work just fine.

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#### Gonzo78

Joined May 2, 2016
3
Thank you for the responses. I am using this to build a light model for university, so basically to show the mechanism of how the lamp would work, not for long term use.

I would be using the led strip connected to a 12 v transformer pluged to the mains.

The 5m i think refers to 5 meters of the led strip.

As i mentioned i would only be using less than half a meter for this project, would that then make a difference in terms of amps needed for the reed switch?

Thanks

#### dl324

Joined Mar 30, 2015
15,828
Welcome to AAC!
(note i will cut the led stip as i only need 12 leds lights )
• Working input Voltage: 12V DC
• Working power: 9.6W/5M
It should be fine. Depending on how the LEDs are wired; 12 LEDs will consume around 12/600 of the 9.6W and draw about 16mA. 16mA @ 12V is well within the specs of the switch.

Take the advice from post #2 and measure the current to be certain.

#### Tonyr1084

Joined Sep 24, 2015
7,454
Post #3 was edited. Did you review it?