# Can you run an amp rack fan off the remote wire?



## Danometal (Nov 16, 2009)

Hello.

It's time to button up my install by building a nice amp rack. I'm sending the wife to an all day trip to the day spa on Saturday, so I'll have 8 hours of me time to play with my system.

I want to aerate my hot natured 4 Boston GTA-704 amp, but I don't want to remove any more interior panels (other than removing the back seat) to run any more wires. 

Will the crappy CCA remote wire from the HU to the amp rack be enough to run a 12V computer fan? I love the idea of the fan coming on whenever my amps are turned on.

Thanks!


----------



## Timelessr1 (Feb 12, 2010)

no you should not run the fan DIRECTLY off the remote wire.....what you want to do is let the remote wire trigger a relay which will power the fan


----------



## Aaron'z 2.5RS/WRX (Oct 24, 2007)

Not the best idea, but there are relays 

They dont draw much, but the RTO doesnt have much

Sent from the other side using mind bullets...(YapaTalk)


----------



## minbari (Mar 3, 2011)

no, most remote wires are rated for 300mA. depending on the size of the fan, those can pull as much as 1A. you definitely want to isolate it with a relay.


----------



## Timelessr1 (Feb 12, 2010)

the best solution woud be to use your remote wire to trigger the relay and then from the relay turn on ALL your other pieces...amps/processors and can also run the fan then too


----------



## Danometal (Nov 16, 2009)

Excellent! Thanks!


----------



## Danometal (Nov 16, 2009)

Oh... where would be the best place to get a relay? I'm not familiar with them. Thanks!


----------



## minbari (Mar 3, 2011)

any auto parts store. standard bosch style relay with a wiring hardness shouldn't more than $15


----------



## nutxo (Feb 24, 2008)

minbari said:


> any auto parts store. standard bosch style relay with a wiring hardness shouldn't more than $15


I pay like 3 bucks from a local shop. 

I was taught that anytime you have more than one amp you should have a relay. I power ,or have powered, 3 remote wires, a basscube and 2 crossflow fans off one relay.


----------



## minbari (Mar 3, 2011)

nutxo said:


> I pay like 3 bucks from a local shop.
> 
> I was taught that anytime you have more than one amp you should have a relay. I power ,or have powered, 3 remote wires, a basscube and 2 crossflow fans off one relay.


Ya, SE has em for like $5 too. But auto parts stores cost a bit more for some reason

Sent from my Motorola Electrify using Tapatalk 2


----------



## Danometal (Nov 16, 2009)

Sweet. Auto parts store will win, as I don't have time to wait for one to be shipped. Besides, I ordered some speaker baffles from them, and they got lost in the mail. Had to make some.


----------



## kmarei (Nov 13, 2009)

I've used the PAC TR-4 
Easy to install, and sure beats wiring a relay


----------



## nosaj122081 (Apr 7, 2012)

You can use a transistor, too. I like that b/c it's a lot neater than a relay, takes up hardly any space at all, and cost almost nothing (in my case, they DO cost nothing)... OK, maybe not A LOT neater, but...

My P1224 will be playin' by the end of the weekend. 2.3ft^3 ported somewhere between 25Hz and 30Hz, thanks for the advice.


----------



## Danometal (Nov 16, 2009)

kmarei said:


> I've used the PAC TR-4
> Easy to install, and sure beats wiring a relay


Cool. Sonic has one. Is 2 amps of current enough? The sticker on my fan says 2.1 amps.


----------



## minbari (Mar 3, 2011)

kmarei said:


> I've used the PAC TR-4
> Easy to install, and sure beats wiring a relay


how is that? a relay has 4 wires. PAC tr7 has 4 wires.........BFD



Danometal said:


> Cool. Sonic has one. Is 2 amps of current enough? The sticker on my fan says 2.1 amps.



no, that is not enough. obviously the fan exceeds the tr7. you would want some amount of safety margin anyway. I wouldnt run more than 1.5amps on a 2a supply, but that is just me. 

a basic bosch relay has 15A contacts. if you can exceed that from a couple fans and some amplifier turn-ons, you will have my adoration


----------



## Danometal (Nov 16, 2009)

nosaj122081 said:


> You can use a transistor, too. I like that b/c it's a lot neater than a relay, takes up hardly any space at all, and cost almost nothing (in my case, they DO cost nothing)... OK, maybe not A LOT neater, but...
> 
> My P1224 will be playin' by the end of the weekend. 2.3ft^3 ported somewhere between 25Hz and 30Hz, thanks for the advice.


I need to learn up on relays and transistors, it looks like. I don't even know what transistors do. lol

And, definitely report back with your impressions with the JBL. IME: Roof flex and bouncy wipers with a single 12? Yep. Transparent blending and transient attack? Yep. That too. 

I have raped mine with over 800 watts RMS on tap for over a year, and it POUNDS stupid low and stupid hard with bassy tracks, and sings so sweet on the SQ. 

So.. loud, SQ, tank - all in one for $150. Unbelievable value.


----------



## minbari (Mar 3, 2011)

Danometal said:


> *I need to learn up on relays and transistors, it looks like. I don't even know what transistors do. lol*
> 
> And, definitely report back with your impressions with the JBL. IME: Roof flex and bouncy wipers with a single 12? Yep. Transparent blending and transient attack? Yep. That too.
> 
> ...


in this case, they are just a solid state relay (switch) its not hard to biuld, but you do need a soldering iron and some know-how. the only downside to a transistor is heat. if you are gonna switch 2+ amps with it you are gonna have to put a heat sink on it or it will pop.


----------



## Danometal (Nov 16, 2009)

minbari said:


> in this case, they are just a solid state relay (switch) its not hard to biuld, but you do need a soldering iron and some know-how. the only downside to a transistor is heat. if you are gonna switch 2+ amps with it you are gonna have to put a heat sink on it or it will pop.


Sounds like the relay is the way to go. Just spoke with my cousin-in-law, who has a 5 inch fan and a relay for me (I've been helping him with his system anyway).


----------



## CrossFired (Jan 24, 2008)

Danometal said:


> I need to learn up on relays and transistors, it looks like. I don't even know what transistors do. lol


Dont even bother with a transistor. The relay you want will looks like one of these(about 1"x1"x1.5").


----------



## kilostoys (Jan 28, 2011)

yup, relay it. i run 3 amp turn-ons, 2 eq xovers, and a fan all on a single relay and am still less than half of its limits....

--kilo


----------



## steffanan (Dec 9, 2010)

They are called single pin single throw relays, not "Bosch style" or "5 pin". If you are having a hard time finding one


----------



## IBcivic (Jan 6, 2009)

steffanan said:


> They are called single POLE, single throw relays, not "Bosch style" or "5 pin". If you are having a hard time finding one


FIXED

"Pole" as in polarity


----------



## steffanan (Dec 9, 2010)

Shoot, I saw that right after I posted it


----------



## minbari (Mar 3, 2011)

IBcivic said:


> FIXED
> 
> "Pole" as in polarity


Pole as in how many common contacts. Had nothing to do with polarity

Sent from my Motorola Electrify using Tapatalk 2


----------



## Danometal (Nov 16, 2009)

Cousin-in-law is on his way with a Bosch style relay! Too bad I have to diagnose a tweeter problem before I get started. :/ (My tweeters are making a high pitch crackling noise like a cellophane (sp?) on some notes)

Edit: In case anyone reading this has any ideas before I make a thread about it later, I heard the sound to a lesser extent with my factory tweeters, but they were just quieter tweeters in general.


----------



## IBcivic (Jan 6, 2009)

minbari said:


> Pole as in how many common contacts. Had nothing to do with polarity
> 
> Sent from my Motorola Electrify using Tapatalk 2


....yeah, sure


----------



## minbari (Mar 3, 2011)

Roll you're eyes all you like, switches don't have polarity

Sent from my Motorola Electrify using Tapatalk 2


----------



## IBcivic (Jan 6, 2009)




----------



## Danometal (Nov 16, 2009)

Well, got the amp rack done today, but not installed. I see about the fan and the relay in the near future.


----------



## ahardb0dy (Feb 19, 2012)

Wire the relay like this, they have numbers on the bottom next to the pins/terminals:

30 - power in ( connect to your distribution block if you are using one), use a fuse
87 - power out (to fan positive)
86 - control current in ( wire to remote turn on wire)
85 - to ground

some relays have 5 terminals, the extra one will be labeled 87A, these are normally referred to as a "change over" relay), you can still use it like a 4 terminal relay just don't use the 87A.

How the "change over" relay works is, when the relay is off, terminal 87A has power when the relay is turned on (triggered) 87 has power and 87A is off.


----------



## nosaj122081 (Apr 7, 2012)

minbari said:


> Roll you're eyes all you like, switches don't have polarity
> 
> Sent from my Motorola Electrify using Tapatalk 2


He's totally correct... single pole relays (whether single or double throw) has a single set of poles, double pole is functionally the same as a pair of single pole relays, just in the same package. No polarity... 

Me, I still like transistors much better.


----------



## IBcivic (Jan 6, 2009)

I never said that switches or relays have polarity...

Should I have said "pole" as in a polish person, a telephone pole, or voting pole, instead?
<<insert rolling eyes here>>

The nomenclature "POLE" is related to polarity....Yes there is no set polarity on a switch/relay....it is just a universally accepted designation Eg> with a DPDT switch, you could switch both "polarities" on a simple DC circuit. 

I did not make those designations up...so , there...I'm done


----------



## steffanan (Dec 9, 2010)

Pointless battle thread 2012 has been established. Go for it guys


----------



## Danometal (Nov 16, 2009)

ahardb0dy said:


> Wire the relay like this, they have numbers on the bottom next to the pins/terminals:
> 
> 30 - power in ( connect to your distribution block if you are using one), use a fuse
> 87 - power out (to fan positive)
> ...


You are awesome! I am going to try this, literally after I finish my pizza! I looked at the relay I have, and it indeed has the 5 numbers you referenced, so YAY, my amp rack is getting a fan!


----------



## sqshoestring (Jun 19, 2007)

I run the slower PC case fans, iirc they are ~.4A each. I've run a fan and two amps many times but newer HU keep saying less and less current on the remote. You should be able to run 3 amps normally before needing a relay, but it is safer to just run one after two amps or when adding fans.


----------



## ahardb0dy (Feb 19, 2012)

the control current needed to activate most relay's is about 150 ma so the remote turn on lead should be more than enough to trigger a relay.


----------



## Danometal (Nov 16, 2009)

Well, I got the amp rack in and the relay and fan hooked up, but the fan doesn't work. It appears that, while working the amp rack into place and hooking up power and ground mains and the speaker wires, I accidentally pulled the fan hot wire out of its butt connector. 

Unfortunately, I'm not too happy with my fan tower I fabbed up, so I may need to re-evaluate as to whether I really need it. At least I have strong turn on current with the relay in place until I decide.


----------



## minbari (Mar 3, 2011)

IBcivic said:


> I never said that switches or relays have polarity...
> 
> Should I have said "pole" as in a polish person, a telephone pole, or voting pole, instead?
> <<insert rolling eyes here>>
> ...


*sigh* dont talk unless you know what you are talking about. it has nothing to do with polarity and never did.
you dont "switch polarities" that doesnt even make sense.

Relay - Wikipedia, the free encyclopedia


----------



## vwjmkv (Apr 23, 2011)

ahardb0dy said:


> Wire the relay like this, they have numbers on the bottom next to the pins/terminals:
> 
> 30 - power in ( connect to your distribution block if you are using one), use a fuse
> 87 - power out (to fan positive)
> ...


pin 30 connected to distribution block via 18AWG wire? i am sorry, i am still very dense when it comes to wiring and the such. i want to make sure i do everything correct the first time around. also, if I'm using 2 fans, (intake and exhaust) can i still use just one relay? if diagram can be posted it would help me tons, I'm more of a hands on/ visual person. type is tough for me to grasp. THANK YOU MUCH!

CC


----------



## minbari (Mar 3, 2011)

here is how to wire it. the "+12V" is from your distro-block

those relays have 15A contacts. you could power 10 fans and not overpower it


----------



## Danometal (Nov 16, 2009)

I removed my ugly fan tower today. When I was under the amp rack, I went ahead and connected 2 capped off wire leads to the relay so I can simply plug a different fan design into it without even moving the amp rack again. I'm thinking I can mount a larger fan right under the rear shelf blowing straight down on the amps. 

Here's a pic of my new amp rack. It's sandwiched between the sub box and the fold down back seats right under the rear deck:


----------



## req (Aug 4, 2007)

do you really need a diode in between 86 and 85?


----------



## minbari (Mar 3, 2011)

req said:


> do you really need a diode in between 86 and 85?


its a safety measure. when a relay turns off it has an inductive kick from the collapsing magnetic field (the field that holds the relay on) this kick can generate 70-100+volts. the diode is there to protect the HUs RTO wire.


----------



## Danometal (Nov 16, 2009)

minbari said:


> its a safety measure. when a relay turns off it has an inductive kick from the collapsing magnetic field (the field that holds the relay on) this kick can generate 70-100+volts. the diode is there to protect the HUs RTO wire.


Is that built into the relay? You got me concerned.


----------



## minbari (Mar 3, 2011)

if it is a standard bosch relay, no. alot of the wiring harnesses have it biult in. if it doesnt, you should add it on. rat shack has em for a couple bucks. 1n1001, or anything that is a "rectifying diode"

make sure that you install it correctly. the diode has a banded line at one end. you want to put that line towards the +12V side.


----------



## Timelessr1 (Feb 12, 2010)

minbari said:


> if it is a standard bosch relay, no. alot of the wiring harnesses have it biult in. if it doesnt, you should add it on. rat shack has em for a couple bucks. 1n1001, or anything that is a "rectifying diode"
> 
> make sure that you install it correctly. the diode has a banded line at one end. you want to put that line towards the +12V side.


Maybe i jsut need sleep...but in your diagram, if you are trying to protect the RTO, wouldnt the spike still occur in the relay internally as the charge is being deactivated using your diagram? wouldnt it jsut be benificial to put the diode on the RTO like BEFORe connecting it to the realy? This way the relay cant back feed ANYTHING to the RTO line...


----------



## minbari (Mar 3, 2011)

Timelessr1 said:


> Maybe i jsut need sleep...but in your diagram, if you are trying to protect the RTO, wouldnt the spike still occur in the relay internally as the charge is being deactivated using your diagram? wouldnt it jsut be benificial to put the diode on the RTO like BEFORe connecting it to the realy? This way the relay cant back feed ANYTHING to the RTO line...


nope, that is not how you connect it. the diagram I showed is acurate. how it works is when the relay is on, the diode is forced off. (it is on the relay backwards, on purpose) when the relay de-energises the inductive kick starts to rise turning the diode on. once it turns on it shorts the kick out entirely. sinec the diode only needs about 0.7volts to turn on , the kick is eliminated.

what you are talking about doing would cause the diode to fail eventually. a standard 100v recitifying diode has an RMS reverse voltage of about 50V. keep exceeding it and over time it will break down and it will conduct in both directions.


----------



## req (Aug 4, 2007)

gotcha.


----------



## Danometal (Nov 16, 2009)

It appears like a standard Bosch relay. It came off somebody's car, off a series of relays hooked together. So far everything is turning on and off OK.


----------



## myhikingboots (Oct 28, 2010)

SUB'D


----------



## Timelessr1 (Feb 12, 2010)

minbari said:


> nope, that is not how you connect it. the diagram I showed is acurate. how it works is when the relay is on, the diode is forced off. (it is on the relay backwards, on purpose) when the relay de-energises the inductive kick starts to rise turning the diode on. once it turns on it shorts the kick out entirely. sinec the diode only needs about 0.7volts to turn on , the kick is eliminated.
> 
> what you are talking about doing would cause the diode to fail eventually. a standard 100v recitifying diode has an RMS reverse voltage of about 50V. keep exceeding it and over time it will break down and it will conduct in both directions.


Ahhh..got it...so it shorts out the spike...and not jsut stop the reverse feed back to the RTO...learn something new everyday.. thanks


----------



## minbari (Mar 3, 2011)

Yuppers, much more reliable

Sent from my Motorola Electrify using Tapatalk 2


----------



## Budget (Feb 9, 2010)

minbari said:


> here is how to wire it. the "+12V" is from your distro-block
> 
> those relays have 15A contacts. you could power 10 fans and not overpower it


I was doing some research on this and found out how to wire it all up, but how much ... amps? is the resistor supposed to be? Sorry that thing that you put between the 85/86 poles. 

I am going to be using 5 fans (I think the larger ones are 120mm and the other two are small ones that I got from a thermal fan meter and my old external hdd case (all are 12v)). What would be a good size fuse for the main power for the relay? 

Cooling Fans

- 1st diagram; does there have to be a fuse at ea. fan? or can I make the main fuse to the relay enough so that it can handle all 5 (so like say ... 15a fuse to the relay via add a fuse connector, and wire the rest like it should be without putting fuses to ea. fan)?


----------



## Danometal (Nov 16, 2009)

I just disconnected my relay after realizing it doesn't have the protection diode in it, and hooked up just the remote wires until I can get to Radio Shack. How can I tell if I have already done any damage to my HU?


----------



## nosaj122081 (Apr 7, 2012)

Budget said:


> I was doing some research on this and found out how to wire it all up, but how much ... amps? is the resistor supposed to be? Sorry that thing that you put between the 85/86 poles.
> 
> I am going to be using 5 fans (I think the larger ones are 120mm and the other two are small ones that I got from a thermal fan meter and my old external hdd case (all are 12v)). What would be a good size fuse for the main power for the relay?
> 
> ...


It's a diode, not a resistor... Just get a diode that the part number begins with 1N... and it'll be fine. It's just to protect the sensitive equipment from a potentially damaging reverse voltage spike when voltage is taken away from the coil of the relay. Make sure the little line on the diode is closer to pin 86 (or whichever you connect the remote from the HU to), polarity MATTERS!

A single fuse on the input side of the relay will be fine. Add up the amp draw of your fans (or Google similar ones, and add up those amp draws) and get close enough (a bit higher, in this case, is better than a bit lower). I would venture a guess that a 10A fuse would be cutting it fairly close, but would work. I think a 15A like you mentioned would be an excellent choice.


----------



## nosaj122081 (Apr 7, 2012)

Danometal said:


> I just disconnected my relay after realizing it doesn't have the protection diode in it, and hooked up just the remote wires until I can get to Radio Shack. How can I tell if I have already done any damage to my HU?


As long as it works, you're fine... Just toss a DMM on it.

The diode is one of those things many, many people have gotten away without many, many times. It's just CORRECT electrical practice, the right way. Good insurance for a quarter . It's not necessary if what is connected to the relay coil (ie, a switch), won't get damaged by a reverse spike. I fried 2 microcomputers in college because I blew up an output before someone told me about the diode thing.


----------



## Budget (Feb 9, 2010)

nosaj122081 said:


> It's a diode, not a resistor... Just get a diode that the part number begins with 1N... and it'll be fine. It's just to protect the sensitive equipment from a potentially damaging reverse voltage spike when voltage is taken away from the coil of the relay. Make sure the little line on the diode is closer to pin 86 (or whichever you connect the remote from the HU to), polarity MATTERS!
> 
> A single fuse on the input side of the relay will be fine. Add up the amp draw of your fans (or Google similar ones, and add up those amp draws) and get close enough (a bit higher, in this case, is better than a bit lower). I would venture a guess that a 10A fuse would be cutting it fairly close, but would work. I think a 15A like you mentioned would be an excellent choice.


looked on Google and found some diodes, but ... there are different amperages, thinking about getting the 3a. 

NTE5800 - Rectifier-50 PRV 3A Axial Lead : Rectifiers | RadioShack.com

3A Barrel Diodes : Diodes | RadioShack.com

Diodes & rectifiers - Component parts - RadioShack.com

sounds about right? when I was reading in that link about adding the fans, it said that at most a fan will be around 3a or something like that (reason why I said 15a fuse, was mainly guessing to be honest).


----------



## minbari (Mar 3, 2011)

Danometal said:


> I just disconnected my relay after realizing it doesn't have the protection diode in it, and hooked up just the remote wires until I can get to Radio Shack. How can I tell if I have already done any damage to my HU?


if the RTO still works, you didnt damage it


----------



## minbari (Mar 3, 2011)

Budget said:


> looked on Google and found some diodes, but ... there are different amperages, thinking about getting the 3a.
> 
> 
> 
> sounds about right? when I was reading in that link about adding the fans, it said that at most a fan will be around 3a or something like that (reason why I said 15a fuse, was mainly guessing to be honest).


that one will work, its a bit of overkill, but will work. a 1amp or less diode will work fine.


----------



## nosaj122081 (Apr 7, 2012)

Budget said:


> looked on Google and found some diodes, but ... there are different amperages, thinking about getting the 3a.
> 
> NTE5800 - Rectifier-50 PRV 3A Axial Lead : Rectifiers | RadioShack.com
> 
> ...


Yeah, like Minbari said, you don't need a diode of that girth... They'll work just fine, but with the reverse voltage spike, current really isn't an issue. Even the cheapest 1N4004 will do the trick perfectly, and every RadioShack in America has them in stock. Probably about a dollar... Hell, if they don't, I'll mail you one.

Those 3A diodes are handy for a basic half-wave rectifier to cut the voltage down on Christmas lights to dim them :santa2:.


----------



## Danometal (Nov 16, 2009)

Cool. My RTOs are working normally. I will go to Radio Shack tomorrow and see about a diode (maybe they can solder one on my relay real quick), or maybe I'll see about a smaller relay will a less inductive coil in it.


----------



## minbari (Mar 3, 2011)

Danometal said:


> Cool. My RTOs are working normally. I will go to Radio Shack tomorrow and see about a diode (maybe they can solder one on my relay real quick), or *maybe I'll see about a smaller relay will a less inductive coil in it*.


nope, that will not make much difference. you might get only 70 volts instead of 100 volts. still better to protect it.


----------



## nosaj122081 (Apr 7, 2012)

Danometal said:


> Cool. My RTOs are working normally. I will go to Radio Shack tomorrow and see about a diode (maybe they can solder one on my relay real quick), or maybe I'll see about a smaller relay will a less inductive coil in it.


I believe it is current RadioShack company policy that the salespeople don't touch jack **** in a technical manner (or at least that's the way they act at my local store)... This is probably a good thing, based on what I've seen there. If you don't want to solder it yourself, come up with something using crimp-on connectors. It doesn't have to be physically ON the relay, just as long as it's somewhere in the circuit parallel to the relay's coil.


----------



## Budget (Feb 9, 2010)

nosaj122081 said:


> Yeah, like Minbari said, you don't need a diode of that girth... They'll work just fine, but with the reverse voltage spike, current really isn't an issue. Even the cheapest 1N4004 will do the trick perfectly, and every RadioShack in America has them in stock. Probably about a dollar... Hell, if they don't, I'll mail you one.
> 
> Those 3A diodes are handy for a basic half-wave rectifier to cut the voltage down on Christmas lights to dim them :santa2:.




1N4004 Micro 1-Amp Rectifier Diode : Diodes | RadioShack.com

going to hit up the RS down the street to see if they have this, if not I'll hit up another within the city (I think I have seen these packs in those tool bins they have with all the switches/etc. in them).


----------



## Budget (Feb 9, 2010)

got em!!! they have a 2 pack for like $1 something.


----------



## MarkZ (Dec 5, 2005)

minbari said:


> nope, that will not make much difference. you might get only 70 volts instead of 100 volts. still better to protect it.


Still not a bad idea to use one with a smaller coil though. I've always avoided using the Bosch type relays. Most of the time, their coil resistances are so damned low.


----------



## minbari (Mar 3, 2011)

MarkZ said:


> Still not a bad idea to use one with a smaller coil though. I've always avoided using the Bosch type relays. Most of the time, their coil resistances are so damned low.


from that aspect maybe, but it wont effect the the need for the protection diode.

I have never had a problem with a HU powering a bosch relay. most draw less than 250mA, less than a HU will source.


----------



## MarkZ (Dec 5, 2005)

I've seen coil resistances usually in the ballpark of 30 ohms. Which translates to like 400mA or so. Doesn't make a lot of sense to use a relay to reduce consumption if you're powering less than 5 amplifiers. Unless you're setting up a wind tunnel in your trunk.


----------



## Danometal (Nov 16, 2009)

MarkZ said:


> I've seen coil resistances usually in the ballpark of 30 ohms. Which translates to like 400mA or so. Doesn't make a lot of sense to use a relay to reduce consumption if you're powering less than 5 amplifiers. Unless you're setting up a wind tunnel in your trunk.


I like the thought of a wind tunnel in my trunk.


----------



## Budget (Feb 9, 2010)

another question, to ground the fans, can join the fan grounds to the amp ground terminal? or do I have to ground the fans separately?


----------



## The Tube Doctor (Nov 24, 2009)

Transistor turn-on can handle most fan & RTO loads. TIP120 works for me, 
no problem up to 4A. 
Over that and I'll use a 2n6387 with a little heat-sink tab on it. Good for nearly 10A.
No coil transient (pop) and can be made quite compact. Refer to the photo link for 
a comparison between Bosch-style relay & transistor turn on.
image8.jpg picture by thetubedoctor - Photobucket


----------



## minbari (Mar 3, 2011)

Budget said:


> another question, to ground the fans, can join the fan grounds to the amp ground terminal? or do I have to ground the fans separately?


either way. doesnt really matter.


----------

