How can I turn a continuous but press into a 5 sec pulse?

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Thanks for continuing to provide advice/support on this. I will look into the alternative circuits if my quick an dirty solution become a problem.

This morning my reed switch arrived but there appears to be a problem. It's the standard "closed when magnet is near" type and I wanted the reverse. I thought that's what the product description said it could be set to.

PHP: 
Product Name       : Magnetic Door Contacts
Model              : MC-56
Switch Type        : NC, NO, NC&NO
Rated Current      : 500mA
Rated Voltage      : 100V DC
Rated Power        : 10W
Operating Distance : 40-60mm

Doesn't NC, NO, NC&NO suggest it's capable of being configured to Normally Close or Normally Open? I mean without the aid of additional circuitry?
 
dougy83 said:
How many wires from the reed switch? There should be 3 - Com, NC & NO
Click to expand...

Only 2 wires although it's hard to see in the pic:
**broken link removed**

I assumed you'd set the NC, NO using a physical/mechanical adjusted (yes I'm a electronics noob).

So would you say this is mis-advertised? Or am I missing something?
 
FreeZey said:
I assumed you'd set the NC, NO using a physical/mechanical adjusted (yes I'm a electronics noob).
Click to expand...
I've only seen a few, but they had either 2 wires (& happened to be NO) or 3 wires (com, no, nc). I think putting a switch in would be more hassle than just putting an extra wire.

FreeZey said:
So would you say this is mis-advertised? Or am I missing something?
Click to expand...
Yes, it sounds like you're missing a N/C connection.

It's not hard to invert the sense of the switch if you're just feeding it into the pulse extender circuit; just a matter of adding a high-value pull-up (or down) resistor in the right place. Do you have the schematic of the pulse extender you're planning on using?
 
dougy83 said:
I think putting a switch in would be more hassle than just putting an extra wire.
Click to expand...
Arrr yes this makes sense, like a micro switch.

dougy83 said:
Yes, it sounds like you're missing a N/C connection.
Click to expand...
So would you say I have a valid complaint based on the way it was described on their website?

My current circuit is:
Battery - Lamp - NC Reed Switch (in a loop/series)

I.e. moving the magnet away from the reed causes the light to come on, so absolutely anything involving resisters, capacitors etc is a significant increase in complexity. Although it is one I'm likely going to have to accept and start learning enough about electronics to translate these circuit diagram suggestions members have been posting into a physical veroboard design and component shopping list.
 
I don't get it? I looked at that switch on several sites and was unable to find much information about it. Typically magnetic switches look like the first attached image which shows several varieties. You can easily pick out the N/O and N/C as well as both in a single glass envelope. The second image shows a typical N/O & N/C switch with the 3 terminals (Common, N/O and N/C). They happen to be switches made by formerly Hermetic Switch, Inc. and is now is now HSI Sensing.

The actual switches shown in the image do have a cover piece but I don't see that in the original linked to images?

Ron
 

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What I’ve been sent is exactly like the second image you posted except:
  • Rather than providing a screw point to attach wires mine has 2 wires already attach coming from the housing.
  • The unit it completely enclose. The reed switch is sealed inside a resin with just the 2 wires protruding from the housing.
  • Critically, there are only 2 wires providing N/O functionality, no 3rd wire to offer an N/C connection
 
If you want to go the switch route for this project and if you are located in the US I'll send you one of the switches I used in the picture. I have several collecting dust around here. Yours for the asking if it will fit your needs. I just don't want to screw with mailing a silly little switch outside the US. Postage is on me, no big deal.

Ron
 
It's very kind of you to offer sir but I'm afraid I'm in the UK.

For now I'm just here to confirm with those who know about electronics that what I've purchased was wrongfully specified on the retailers website. I.e. this is clearly not a switch that can be described as "Switch Type : NC, NO, NC&NO " Since it has only 2 connections and offers only NO functionality.
 
Well then it is on to making what you have work for you. Which can be done with a little learning.

Ron
 
If the description/part number is for a line/range of products, "Switch Type : NC, NO, NC&NO" could mean any one of the 3 listed options. Otherwise, what they've written is ambiguous but of course you can argue that the listed functionality should be supported. Simply write to your distributer and try to correct the situation.
 
Ok I asked the retailer about this reed switch and their response was a bit cryptic:
I get the feeling they forwarded my enquiry onto the Chinese manufacture and this cam back from them. I also looks like they're talking about an electro-magnet in parts.

Strange.
 
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