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Author: Subject: Single output relay to double output using diode
JekRankin

posted on 14/5/18 at 08:35 PM Reply With Quote
Single output relay to double output using diode

I've redone my car's electrics using 280 micro relays and fuses. Really pleased with how it has turned out.

However....I forgot to order a double output relay for my hazard circuit, and it seems no such thing exists in a 280 micro size.

My fusebox is full, so I can't easily add another relay single output relay. Instead, can I simply convert my single output relay to a double output one using a diode? e.g connect the power feeds to both indicator circuits to the single output relay, but use a diode on one of the feeds to isolate them from each other when the hazard relay is not energised?

Hope that question made sense..

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02GF74

posted on 14/5/18 at 09:48 PM Reply With Quote
What do you mean by single and double output.

Relays are denoted by poles and throws.

As stolen from Wikipedia.

SPST-NO (Single-Pole Single-Throw, Normally-Open) relays have a single Form A contact or make contact. These have two terminals which can be connected or disconnected. Including two for the coil, such a relay has four terminals in total.
SPST-NC (Single-Pole Single-Throw, Normally-Closed) relays have a single Form B or break contact. As with an SPST-NO relay, such a relay has four terminals in total.
SPDT (Single-Pole Double-Throw) relays have a single set of Form C, break before make or transfer contacts. That is, a common terminal connects to either of two others, never connecting to both at the same time. Including two for the coil, such a relay has a total of five terminals.
DPST Double-Pole Single-Throw relays are equivalent to a pair of SPST switches or relays actuated by a single coil. Including two for the coil, such a relay has a total of six terminals. The poles may be Form A or Form B (or one of each; the designations NO and NC should be used to resolve the ambiguity).
DPDT Double-Pole Double-Throw relays have two sets of Form C contacts. These are equivalent to two SPDT switches or relays actuated by a single coil. Such a relay has eight terminals, including the coil
The S (single) or D (double) designator for the pole count may be replaced with a number, indicating multiple contacts connected to a single actuator. For example, 4PDT indicates a four-pole double-throw relay that has 12 switching terminals.

Also can you draw a circuit diagram to show what you want to achieve, far less ambiguous than the description, at least for me.

[Edited on 14/5/18 by 02GF74]





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paulc

posted on 14/5/18 at 11:58 PM Reply With Quote
Hi,

This is what i'm going to do with my hazards / indicators.

Description
Description


One caution, haven't actually tested it yet (Porbably a couple more weeks before that'll happen)

But I'm reasonably certain it'll work.

(12V_SW is the switched feed from the ignition switch)

The switching of the feed to the flasher relay is so the Hazards work with the ignition off (IVA requirement)
but the indicators only work when the ignition is on.



Paul

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ken555

posted on 15/5/18 at 08:22 AM Reply With Quote
That should work.

I have a similar set up but with a couple more diodes to power a single dash light









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JekRankin

posted on 15/5/18 at 09:18 AM Reply With Quote
Yeah, sorry it would have been clearer with a diagram. I'll get one up later today when I get a spare min.

Instead of 'double output relay', I should have said 'Relay with dual contacts' - this is a single throw relay, but the armature contacts two output pins at once. This allows you to send power to both the left hand and right hand indicator circuits at the same time, but when the relay is switched off, the left and right hand indicator circuits are isolated from each other. See pic below:



From the two diagrams posted, it looks like I can achieve a similar logic using diodes...but I'll get a sketch of my circuit up to check.

Cheers,
Jek

[Edited on 15/5/18 by JekRankin]

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craigdiver

posted on 15/5/18 at 12:34 PM Reply With Quote
quote:
Originally posted by JekRankin
I've redone my car's electrics using 280 micro relays and fuses. Really pleased with how it has turned out.

However....I forgot to order a double output relay for my hazard circuit, and it seems no such thing exists in a 280 micro size.

My fusebox is full, so I can't easily add another relay single output relay. Instead, can I simply convert my single output relay to a double output one using a diode? e.g connect the power feeds to both indicator circuits to the single output relay, but use a diode on one of the feeds to isolate them from each other when the hazard relay is not energised?

Hope that question made sense..


Couple of diodes will be fine, this is how the old moss alarms managed to flash all indicators without effecting normal indicator operation.





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gremlin1234

posted on 15/5/18 at 05:44 PM Reply With Quote
if you are using standard bulbs, then the diodes will need to be rated at 4A each

I would use a bridge rectifier, (as per ken555's design above) since its one package, and gives the wire for a panel light.
and go for an 8A,
http://uk.farnell.com/c/semiconductors-discretes/diodes/bridge-rectifier-diodes?forward-current-if-av-=8a

if using led then 1A diodes/rectifier will be fine.

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