activating reed switch

[lerameur]

Hello,

I made myself a small electromagnet to activate a reed switch using a
6v supply. The problem is that I am pulling 3 amps, I do not want the
electromagnet to be bigger by making more turns, I believe there are
such electromagnet on the market that can activate a reed switch with
current in the milliamps. anybody know such device, I looked at
digikey and mouse but I did not find anything under electro magnet.

thanks

ken

 

[Tim Wescott]

lerameur wrote:

Hello,

I made myself a small electromagnet to activate a reed switch using a
6v supply. The problem is that I am pulling 3 amps, I do not want the
electromagnet to be bigger by making more turns, I believe there are
such electromagnet on the market that can activate a reed switch with
current in the milliamps. anybody know such device, I looked at
digikey and mouse but I did not find anything under electro magnet.

thanks

ken

Try using finer wire.

Look under "solenoid".

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[Michael Black]

On Fri, 25 Jul 2008, Bob Eld wrote:

"lerameur" <lerameur@yahoo.com> wrote in message
news:e8cba1a2-1aa8-4e4f-ba59-b9624d250236@b1g2000hsg.googlegroups.com...
Hello,

I made myself a small electromagnet to activate a reed switch using a
6v supply. The problem is that I am pulling 3 amps, I do not want the
electromagnet to be bigger by making more turns, I believe there are
such electromagnet on the market that can activate a reed switch with
current in the milliamps. anybody know such device, I looked at
digikey and mouse but I did not find anything under electro magnet.

thanks

ken

Yes they have reed relays that draw 10mA at 6 volts. Three amps means you
don't have nearly enough turns and, of course, the wire you are using is a
1000 times too fat.

If you are serious about it you'll have to wind them with AWG 44 or thinner
wire. Good luck finding that. Good luck winding that with 10,000 turns. Not
a job for the timid.

Look for reed relays under relays. Jameco has them.



That brings up what the original poster is wanting to use this for.

I was going to say "well can't you buy coils to activate them" and then
I realized standalone reed switches are mostly activated by a permanent
magnet.

So there either has to be a better way, or the poster needs a different
method.

Figure out a mechanical system to move the permanent magnet in close
to activate the switch.

Take apart an existing relay for the coil, and use that.

Or figure out why a normal relay can't be used; there may be
reasons, such as the reed switch has a more direct contact for
RF use, but there really should be a good reason to do it this
way rather than a "normal" relay.

At this point, I'm even willing to believe that the original
poster is unaware of regular relays.

Michael

 

[John Fields]

On Fri, 25 Jul 2008 17:24:52 -0700 (PDT), lerameur
<lerameur@yahoo.com> wrote:

Hello,

I made myself a small electromagnet to activate a reed switch using a
6v supply. The problem is that I am pulling 3 amps, I do not want the
electromagnet to be bigger by making more turns, I believe there are
such electromagnet on the market that can activate a reed switch with
current in the milliamps. anybody know such device, I looked at
digikey and mouse but I did not find anything under electro magnet.

---
Look under "reed relay". Here's one:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=HE100-ND

JF

 

[John Fields]

On Sun, 27 Jul 2008 07:41:05 -0400, "JANA" <jana@NOSPAMca.inter.net>
wrote:

Why not simply get a reed relay?

To wind an efficient electromagnet is not practical.

---
That's not true; the people who make reed relays do it all the time.
---

You will have to use a
very thing gauge of wire, and calculate the proper number of turns and
select the proper core type. Then you will have to task to properly wide the
coil.

---
The core will be the switch, and the rest of it is just knowing the
sensitivity of the switch and providing a coil with the proper
resistance and number of turns to achieve that with the desired coil
voltage and current.
---

You can take an old relay apart that uses the voltage you want and use the
electromagnet, but this may not be practical.

If you look on the web pages where they sell science experiment devices they
have electromagnets. Most of what they sell is on the large size.

---
Please bottom post.

JF

 

[ehsjr]

John Fields wrote:

On Sun, 27 Jul 2008 07:41:05 -0400, "JANA" <jana@NOSPAMca.inter.net
wrote:


Why not simply get a reed relay?

To wind an efficient electromagnet is not practical.


---
That's not true; the people who make reed relays do it all the time.
---


You will have to use a
very thing gauge of wire, and calculate the proper number of turns and
select the proper core type. Then you will have to task to properly wide the
coil.


---
The core will be the switch, and the rest of it is just knowing the
sensitivity of the switch and providing a coil with the proper
resistance and number of turns to achieve that with the desired coil
voltage and current.
---

I'm wondering if the op isn't envisioning something like this:

reed
---====---
(||)
(||)
(||)
+_(||)_-

Coil around a core, core at 90 degrees to the reed,
with maybe a bolt or nail as the core.

Ed

You can take an old relay apart that uses the voltage you want and use the
electromagnet, but this may not be practical.

If you look on the web pages where they sell science experiment devices they
have electromagnets. Most of what they sell is on the large size.


---
Please bottom post.

JF