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Time delay using relays

Hi guys I have a small problem Im hoping someone can help me with. I have magnetic switches on all my windows (open window and circuit closes). Each is wired too two relays the first relay is turned on by the magnetic switch and because of the way they are wired the first turns on the second and then the second stays on and turns the first off. Now on the first relay on a set of normally open contacts this is wired to a keyboard of a computer so each magnetic switch would say type one letter in notepad or for me I have a program that assigns a key to a wav file so when say the kitchen window is open a wav file plays telling me that window is open. Now my problem. The first relay that is wired to the keyboard is only on for less than a second and is in most cases not enough time for the computer to realize that say the letter "M" is pushed. How can I either delay relay one going off or some other way of doing this. I came by the relays free I need 24 circuits like this one.

I hope I have explained it good enough any help would be appreciated Thanks Nikki

Reply to
Nikki
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I can send or post My wiring diagram for the two relays if you tell me where Nikki

Reply to
Nikki

You can post it to news:alt.binaries.schematics.electronic by attaching it as a GIF, JPEG, or other common image file. Then, post a message here giving the name of the post. If you try to post a binary file here, most people will never see it.

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

This circuit delays the turn on of Relay2 (RY2), which means that Relay1 will stay energized for the delay time. When the magnetic switch closes, Relay1 (RY1) energizes. Roughly 1-10 seconds later (depending on the setting of the delay), RY2 turns on. When RY2 turns on, RY1 turns off. Assuming 12 volt relays:

+12V----+-----+-----+------+-------+-----+ | | | | | | [D1] [RY1] | | [D2] [RY2] | | | | | | +-----+ [R1] [POT] +-----+ | | | | | | | c/ [R2C] | +---[ZD1]---| TIP110 | | +| e\\ | | [C1] | | | | | Gnd--MagSw----+-----+------+-------------+

R2C is the normally closed contact of R2 ZD1 is a 6 volt zener diode. POT is a 50K potentiometer configured as a variable resistor. (The center pin and one of the end pins are shorted togther) C1 is 100 uF, 16 V electrolytic D1, D2 - 1N4002 diodes R1 is 10K The transistor is a TIP110

Adjust the pot for the length of time you need RY1 to stay energized. The banded end of the zener diode is on the left, the other diodes (D1,D2) have the band at the top. The magnetic switch can be in either the +12 volt lead or the ground lead.

Ed

Reply to
ehsjr

Thanks guys I have found that If I use a 470uf cap across the relay That holds the relay in long enough. Does anyone have a good (cheap) supplier I need 30 of these Nikki

Reply to
Nikki

I need a little help with the cap Im not sure what type it is I have posted a picture of it at news:alt.binaries.schematics.electronic If someone could tell me what type it is I can look around for a good price on some Thanks again Nikki

Reply to
Nikki

You're going to burn up your mag switches doing that- try tack soldering two additional components on top of the capacitor: View in a fixed-width font such as Courier.

.--------->>---------------------------. | | | | | | | | | +-----+-----------+ | | _|_ | | V+ 10ohm/ / \\ | --- 1W \\ --- | - | |1N4001 K | - +-----+ K relay | + | K | -+- K | --- | | - |470u | | | | | +-----------------+ | | | | | | | / | .--->>----o o----->>------------------. mag sw

Reply to
Fred Bloggs

Great!

Mouser part #: 140-XRL25V470 16 cents each in lots of 10

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As Fred mentioned, I'd be concerned with burning up your mag switches.

Ed

Reply to
ehsjr

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