[Diy_efi] Time delay relay?

[Mike]

At 11:43 PM 23/12/2002 -0800, you wrote:
>When you say coil, do you mean the coils of the relay?

yes - unless there are other coils, latching relay perhaps,

>Basically, here's what I'd like to do as simply as possible:
>
>I have a input on my ECU which runs through a NC switch, to ground. When the
>switch opens, I'd like the input on the ECU to continue to see ground for
about
>300-400ms after the switch opens.

Well if your input to the ECU is high(ish) impedance with a possible
pullup which I'd expect since its looking for a ground, you dont need
a relay - just a capcitor to ground, have you got a oscilloscope
or a multimeter with fast reading scale ?

All you do is put a cap between the input and ground and your same
switch to ground (ie In parallel with cap), when the switch opens
the cap charges up gradually through the pullup on the ECU, so
try a 10uF cap first 16V and measure across it with a multimeter
and see what happens, a 10uF cap over costs about 20c

What is the input precisely used for -  on the ECU ?

rgds

mike


>However best way to do that, you tell me. I was just thinking a relay
would be
>best, but if there is something I can connect along that wire that can do the
>same, all the better.
>
>----- Original Message -----
From: "Mike" <erazmus at iinet.net.au>
>To: <diy_efi at diy-efi.org>
>Sent: Tuesday, December 24, 2002 12:13 PM
>Subject: Re: [Diy_efi] Time delay relay?
>
>
>> Here I go commenting on my own posts,
>>
>> <cough> Whats the duty cycle of your relat and whats it meant
>> to drive ?
>>
>> rgds
>>
>> mike
>>
>>
>>
>> At 11:54 AM 24/12/2002, you wrote:
>> >What the heck, I just realised you only want a few milliseconds,
>> >then thats not a problem unless your coil has very low resitance,
>> >but if its for driving something in an auot then its prob at least
>> >a few hundred ohms,
>> >
>> >Here's my go at ascii art <sigh>
>> >
>> >     ----------------------------
>> >     |                          |
>> >+ve--+---->|------+----->|------+---- coil +ve
>> >                  |
>> >                  |+
>> >                 --- electrolyic
>> >                 --- cap
>> >                  |-
>> >                  |
>> >                  +------------------ coil -ve
>> >                  |
>> >                  |
>> >                  |
>> >             To device which normally pulls relay on
>> >
>> >
>> >Where -->|-- is a diode say a 1N4004 (1Amp) or if you
>> >need something a bit meatier go for a 1N5404 (3A)
>> >
>> >and your electrolytic cap should be 2200uF 25V if your
>> >coil resistance is about 270 Ohms, the 2200 is a preferred
>> >value, you can go up a bit at a time, 3300, 4700 etc or have
>> >a couple if parallel to trim the delay to what you want,
>> >I'm guessing on your coil resistance though, higher coil
>> >resistance wont need such a large capacitor.
>> >
>> >Overall shouldnt cost more than $AUD 3. (since you already
>> >have the coil)
>> >
>> >rgds
>> >
>> >mike
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >At 11:41 AM 24/12/2002, you wrote:
>> >>One very basic method is a big fat capacitor across coil with
>> >>a pair of diodes to isolate the cap from the coil when off...
>> >>
>> >>Discharge time is approx t=1.1xRxC
>> >>
>> >>where R= reistance of coil, and C is the cap value in Farads,
>> >>this way you can get a few seconds with practical caps and
>> >>a K or so or coil resistance,
>> >>
>> >>But to get 100s best to put a schmitt trigger and caps on the
>> >>drive to the coil transistor, others prob already have a circuit,
>> >>its fairly straightforward,
>> >>
>> >>rgds
>> >>
>> >>mike
>> >>
>> >>
>> >>
>> >>At 02:48 PM 23/12/2002 -0800, you wrote:
>> >>>Where can I find some relays with time delay? I have seen plenty of
>> >>adjustable
>> >>>.1-100s relays, up in the $50-$70 range. I need something simpler. A
>> instant
>> >>>ON/fixed delay OFF relay with a delay of about 250-500ms.
>> >>>
>> >>>
>> >>>_______________________________________________
>> >>>Diy_efi mailing list
>> >>>Diy_efi at diy-efi.org
>> >>>http://www.diy-efi.org/mailman/listinfo/diy_efi
>> >>>
>> >>>
>> >>
>> >>_______________________________________________
>> >>Diy_efi mailing list
>> >>Diy_efi at diy-efi.org
>> >>http://www.diy-efi.org/mailman/listinfo/diy_efi
>> >>
>> >>
>> >
>> >_______________________________________________
>> >Diy_efi mailing list
>> >Diy_efi at diy-efi.org
>> >http://www.diy-efi.org/mailman/listinfo/diy_efi
>> >
>> >
>>
>> _______________________________________________
>> Diy_efi mailing list
>> Diy_efi at diy-efi.org
>> http://www.diy-efi.org/mailman/listinfo/diy_efi
>
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://www.diy-efi.org/mailman/listinfo/diy_efi
>
>

_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi