relay

[Danster]

Hi- please can you help.
Im after a relay which switches at 2vdc.
I dont mind if its a minature or full size.
Ill be switching 12v at about 1A.
Any help much appreciated.
Dan

 

[John Fields]

On 3 Apr 2004 03:59:19 -0800, dan.roberts@uku.co.uk (Danster) wrote:

Hi- please can you help.
Im after a relay which switches at 2vdc.
I dont mind if its a minature or full size.
Ill be switching 12v at about 1A.

---
12VAC or 12VDC and how much current to make it switch? (Coil current
at 2V?)

--
John Fields

 

[CFoley1064]

Subject: relay
From: dan.roberts@uku.co.uk (Danster)
Date: 4/3/2004 5:59 AM Central Standard Time
Message-id: <f59539dd.0404030359.1bdaefef@posting.google.com

Hi- please can you help.
Im after a relay which switches at 2vdc.
I dont mind if its a minature or full size.
Ill be switching 12v at about 1A.
Any help much appreciated.
Dan

The Digi-Key catalog is your friend. Look at the Aromat AGQ200S1H on page 1012
of the current catalog. It's D-K p/n 255-1360-5-ND and is available for $3.80
ea. in single quantities, and will switch 1 amp.

It has a 1.5VDC coil, and has a maximum rated coil voltage of 2.25V, so you
might want to consider using a series 1N4001 diode to drop coil voltage if
you're going over 2.00V.

Good luck
Chris

 

[Danster]

Thanks for your help so far...
The story goes...

I race a vehicle which has a 'shift light' retro-fitted to the coil.
At a certain rpm, an led is illuminated by a 2vdc input from a control
circuit.
-------------------------------------------------------------------------
I want to use one of the currently unused the facia mounted warning
lights, (which is illuminated by earthing a 12vdc (<1A) circuit).
-------------------------------------------------------------------------
Being a mechanical engineer, and not electrical, I thought I could use
a
relay fitted to the 2vdc input from the shift light and open the 12vdc
circuit to earth, therefore turning on the warning light? I dont even
know if this system would work, but to test it, I need to find a 2vdc
relay (preferably in the uk?).
Can somebody please tell me if im on the right track, and if not- why?
Once again, thanks for any help.
Dan

 

[Gareth]

Danster wrote:

Thanks for your help so far...
The story goes...

I race a vehicle which has a 'shift light' retro-fitted to the coil.
At a certain rpm, an led is illuminated by a 2vdc input from a control
circuit.
-------------------------------------------------------------------------
I want to use one of the currently unused the facia mounted warning
lights, (which is illuminated by earthing a 12vdc (<1A) circuit).
-------------------------------------------------------------------------
Being a mechanical engineer, and not electrical, I thought I could use
a
relay fitted to the 2vdc input from the shift light and open the 12vdc
circuit to earth, therefore turning on the warning light? I dont even
know if this system would work, but to test it, I need to find a 2vdc
relay (preferably in the uk?).
Can somebody please tell me if im on the right track, and if not- why?
Once again, thanks for any help.
Dan

For electronic components in the UK try the following:

www.maplin.co.uk

http://rswww.com

www.farnell.co.uk

All three of the above sell relays so hopefully you can find a suitable one.

Do you know which side of the LED is switched? I mean is one side of
the LED permanently connected to ground and one side to a switched +2V
or is it the ground side that is switched?

Gareth.

--
-----------------------------------------------------------------------
To reply to me directly:

Replace privacy.net with: totalise DOT co DOT uk and replace me with
gareth.harris

 

[CFoley1064]

Subject: Re: relay
From: dan.roberts@uku.co.uk (Danster)
Date: 4/3/2004 4:40 PM Central Standard Time
Message-id: <f59539dd.0404031340.25df4ff1@posting.google.com

Thanks for your help so far...
The story goes...

I race a vehicle which has a 'shift light' retro-fitted to the coil.
At a certain rpm, an led is illuminated by a 2vdc input from a control
circuit.
-------------------------------------------------------------------------
I want to use one of the currently unused the facia mounted warning
lights, (which is illuminated by earthing a 12vdc (<1A) circuit).
-------------------------------------------------------------------------
Being a mechanical engineer, and not electrical, I thought I could use
a
relay fitted to the 2vdc input from the shift light and open the 12vdc
circuit to earth, therefore turning on the warning light? I dont even
know if this system would work, but to test it, I need to find a 2vdc
relay (preferably in the uk?).
Can somebody please tell me if im on the right track, and if not- why?
Once again, thanks for any help.
Dan

Hi, Dan. LEDs are current-controlled devices. It sounds like your LED is
being driven by a signal with a series resistor which limits current to, say,
20 mA or so.

If that's the case, putting a relay coil in parallel with the LED won't do the
trick -- neither one will go on. Even replacing the LED with a relay coil is
no good, because the current-limiting resistor will prevent coil actuation.

How about replacing the LED with an optocoupler IC like the 4N32? Pins 1 and 2
are an LED, and pins 4, 5, and 6 are an optotransistor, which you can use to
drive a real transistor to do the job. Maybe something like this will work
(view in fixed font or M$ Notepad):

Optocoupled Automotive Load
VCC VCC
| |
| |
| |
| '------------o
4N32 |
1 | 1 Amp Load
o-----. |5
| |
| ~ |/ .------------o
V ~.--| |
- | |> |
| | | |
| | |4 |
o-----' | | ___ |/
2 |6 o----|___|-----| TIP102
o | 4.7K |>
| |
.-. |
| | |
| |4.7K |
'-' |
| |
| |
=== ===
GND GND

If you want, you can also use a solid state relay, which basically has the
above built in. It's simpler, and also allows a ground-referenced load.

Good luck
Chris