Using relay to obtain cleaner power for headunit?

[MrBinn]

Asking all sifus,

I read in a magazine that installing a 12V relay at the 12v ignition cable of the headunit will eliminate distortion noise and also handphon inteference noise. Is it true? Please comment. Thanks.

 

[trex92]

ermmm.. how can a relay do that? Relay can act as a switch only as far as i know. Unless what they mean is that to top directly the 12V from the battery and using a relay to connect that direct tap to the HU. But actually you can just tap directly without a relay from the battery to the HU.

 

[MrBinn]

If i am not mistaken, relay got four connection point. One direct to battery, one to ground, one to the 12V ignition from car, one to the 12V ingnition from the HU. Correct me if I am wrong.

 

[trex92]

yup.. relay got 4 connection points and sometimes 5. Say points A, B, C and D. Within the relay, A to B is connected and C to D is connected. The way relay works is that if there is a current running from A to B, then relay would connect C to D. If no current running from A to B, then relay would not connect C to D (of course there are many types of relay in the market with diff functions but this is the most common kind used). So actually the relay acts as a switch. The way to connect to HU would be:-

A - Original power cable for ur HU
B - Grounded
C - Direct 12V tap from battery
D - Connect to HU 12V input

So, going back to the above example, then u turn ur ignition to accessory position, the power to A would come ON and since B is grounded, there would be a current flow from A to B. With this current flow, the relay would now connect C to D hence ur HU would power ON....

 

[cacin]

Coming back to the original question, how does a relay do what the magazine claims?

Because relay is just a switch (as far as I know).
If want to use relay to get brighter headlights I heard before la...

regarding the phone interferens one, also another question mark.

 

[trex92]

Coming back to the original question, how does a relay do what the magazine claims?

Because relay is just a switch (as far as I know).
If want to use relay to get brighter headlights I heard before la...

regarding the phone interferens one, also another question mark.

Well, i think the magazine's claim is in the benefits of direct tapping from battery using a relay. Direct tapping from the battery does has it advantages also wan. A dedicated wire supplying 12V instead of sharing the wire with other equipment (as in the case of using relay for the headlights).

 

[Bert]

What a relay does is instead of using the main incoming power supply to the HU (A) it will instead turn on the relay which will bypass the power from the battery (C) to the HU input (D). It is like a little diverter to divert the power from the Batt to HU. The Original pwoer is the on.off switch.

Normally for us ICE fella's we do this. Cheap simple mod that works. BUt we use 8 gauge cables to do so.

 

[MrBinn]

hmm... but the magazine says it will reduce handphone interference noise and engine noise.. how true is that?

 

[oldskolboyz]

???...If I not mistaken the magz is AUDIOZINE is it...dun no the magz still alive...long time never seen at book shop...maybe more than 2yr ooo....which edition can not remember laa...but they show how relay can be manipulate....maybe 4 or 5 way/method can be used for our ICE...

 

[MrBinn]

???...If I not mistaken the magz is AUDIOZINE is it...dun no the magz still alive...long time never seen at book shop...maybe more than 2yr ooo....which edition can not remember laa...but they show how relay can be manipulate....maybe 4 or 5 way/method can be used for our ICE...

I think so. Its a malay magazine. Very old one.. just noticed the article on how relay can help in ICE.

 

[Bert]

The reason we do this is to give a more stable voltage to the HU... normal HU power cable dunno goes through what accessories before comign to the HU so it can give a lot of noise to the HU.

As for the handphoen thing.. mebbe back in 199X when handphoens were the size of bricks.

 

[tikuruok]

guys, is it ok to connect the hu directly from the battery without using the relay? i'll be getting a new hu soon and the thought of giving it clean 12v is interesting. thanks!

 

[Zenn]

just make sure it goes thru a fuse first

 

[tikuruok]

got power cable, bought fuse already. will connect my hu tomorrow. hopefully nothing blown up lah. heheh. will try to add up a relay later... :rolleyes:

 

[trex92]

just be careful with the connection from the battery wan. Make sure u connect the cable to the HU first then only connect it to the battery.

 

[oldskolboyz]

:hmmmm: Last time I saw 1 guy install his HU (CDA7998R) using factory wiring but he add 10,000uf capacitor before his HU it is worth or not..dun no when & where oledi ... :hmmmm:

 

[tikuruok]

i've connected my hu but still using factory wiring. set up all the wires and fuse from the battery already but still a bit afraid to connect it directly to hu. by the way, will a dvd player drain a lot of power? my hu is sony mex-r1.