j_c_a

Hey all,

I'm redoing my stereo and need a sanity check. I'm hooking up multiple amps, a couple fans and some led's. I know just enough electronics to get myself in trouble so if anyone could review and comment on the following schematic I'd appreciate it. Basically, I'm adding a couple fans that will be powered via a relay from the head units turn-on wire. The amps are also on that bus. Additionally, there will be a couple of LED's that turn on when the trunk is opened.

Thanks in advance.

hukares

It's not the most orthodox drawing but I think I know what your notes mean. In which case, it looks goods to me. I really don't know your fusing requirements but I figure that you know them already.

Also, you could make this system work with only relay logic.

j_c_a

Thanks for the feedback. My purpose w/ the transistors is solely to limit the current for the remote turn on and trunk switch. They're probably overkill but I'd rather be safe.

MacGyver

I see nothing wrong with it, offhand. You could trim down the component count and size by using FETs rather than the BJT and relay combos.

NFRs2000NYC

Are you talking about the remote turn on lead? THat is usually a lower voltage wire, and can damage the headunit if you pull that much juice from it. Just want to double check before you fry something.

Andy Kirk

Hi I would check the fuses also. The power to the 3 amplifiers goes through 2x 7.5 Amp fuses in series. This is not necessary. Also I don't know what amplifiers you will be running but the total power to the amplfiers will be limited to less then 100 Watts. I think two of the fuses will need to be higher current. The switch logic (numbering) is confusing to me also I don't know how the switch operates from the diag.
Andy

tk_chatt

Ditto on the comments above.. ( most of them)

Looks like the circuit will operate just fine. Like you said, it is over-kill and there's some redundancy in the fusing, but if you want to put it in, it looks like it'll work.

If I understand your notes, the amp power is being supplied separately? Don't worry about up-sizing your fusing.. it appears that you are just supplying the turn-on inputs from this circuit.

Not knowing your current demands, I would imagine that the 7.5 amp fuses are probably over-kill too. You may want to look at your demands and size your fuses at 125 to 150% of total load.

j_c_a

Thanks all for the comments. Sorry about the less-than-clear diagram, darn eagle cad has some really strange symbols for some relays. The coil and switch for each relay shows seperately, but they have the same name (K1 coil, K1 switch, K2 coil, K2 switch).

Just to clarify, tk_chatt has it correct in that the power to the amps is just for their turn-on circuits. They'll get their main power elsewhere.

As far a fuses, the sizes listed are just guidelines for me. I'll break out the old DVM and fine-tune those, although as mentioned here, I may trim down the number of fuses as they are redundent.

Anyone see any issues w/ this relay:

http://www.mpja.com/viewallpict.asp?dept=311&main=132

It's the bottom one on the page (KEST PN 6520). If there is a more appropriate relay, I'll get it, I was just designing this w/ parts I already have on hand.

Finally, anybody know the best place to tap into the "trunk open" switch. I was planning on tapping directly into the trunk light socket (my new install will cover it anyway) but if there's a better spot please let me know. Unfortunately, I don't have the Helm's manual.

Once again, thanks all.

MacGyver

Dave,

His remote wire is going to the base of the transistor... he'll only pull a milliamp or two.

j_c_a

FYI, just in case anybody is wondering the circuit above works just fine. I had to use different transistors that those listed, but besides that, no problems.