Sarah99GXE

Ok I just got my new box for my speakers. It fits both my 12" subs and has a plexiglass front...pretty nice Anyhow I have a 300 Watt Amp powering the speakers and everytime the bass hits, all of my lights dim (inside car and headlight/brake lights etc)....I'm sure this is normal, however I've just never really noticed it on anyone else's car that I see bumpin around....what can I do about this?

multiplexor

i'm guessing your probably going to need to get one of those 1 farad capacitors... this way when your amp needs the extra power, it'll grab it from the cap, the cap will drain a bit and then refill once power goes back to normal.

Whitemax

Actually if your amp is only 300 watts, just go with an inexpensive 1\2 fard cap. Should be around $50 or so from like www.partsexpress.com

jiaxima96

Probably you could do nothing to eliminate the dimming, except a brand new battery may help a little. When battery gets old its internal resistance goes up. When heavy bass comes there is a surge current needed from the battery. This large current will make a instant voltage drop on the internal resistor so the net voltage on all bulbs are lower than when there is no surge current...
Well theoratically you can do this: change all bulbs to lower voltage, say 6V rated, and install a voltage regulator with a good line regulation capability. Regulator output is 6V. This way no matter the how 12V flutuates the bulbs always get 6V...
Probably nobody will do that, at least no me.

jiaxima96

Oh yeas I forgot the big cap thing. Yes it'll work, unless there is a heavy and loooong bass that drain too much enery from the cap, the voltage will still drop...
Hi Multiplexor, did you receive my email with explanation? Hope your project goes smoothly.

multiplexor

Hello,

yeah got the email i'm still confused on a couple little things.
But i'm going to do some. mainly how R2 and R5 work. since they come directly from the negative, start doing some resistance and then proceed to go on to the circuit. I guess it's just something i need to try...

Oh.. this circuit will work for 3v leds? or was it for 6volts?

Shadow

iTrader: (15)

Maybe it's your battery? With my old battery, my lights would dim everytime the bass hit. Got a cap, and it helped some, but the lights would still dim sometimes. That was only at 300watts total power. Now I'm running a new Holley battery, and the lights never dim. Even when I pulled the cap out and ran the system, just to check. This is at 900watts. But your car is a '99, so I don't imagine the battery would be in too bad shape.

jiaxima96

I don't have schematic with me now. Guess R2 and R5 are in parallel with the other two caps? If yes then R2 and R5 determine the timing of how fast or slow the LED fades.

This circuit will work for both LEDs. The resistor in the LED path determines how bright LED will be, smaller value makes it brighter. You can start with 1 KOhm just to be safe, and go smaller, like 680 Ohm, 560 Ohm, 430 Ohm, etc. Brightness will saturate eventually and LED will burn out if resistor value is too small.

deezo

iTrader: (3)

The fellas are right, get a cap. I just put one in my car.

multiplexor

yeah figured it was for the timing the only thing i have to understand now hehe is how a resistor in parallel with the cap would affect the fade? to modify the fade time dynamically i could always place a variable resistor couldn't i? hmm hehe.

to down the voltage to 3 volts right away, i think i would have to use a 470 ohm resistor... and for the others i will try the values you mentionned.

this is a cool project to mess around with.

Thanks,
Frank

jiaxima96

Resistor in parallel with cap. When the "control signal" charges the C in parallel with R through the upper doide and then the control signal goes down to 0V, the upper diode is reverse biased (no current flows through it so diode is a temperory open circuit now). C will be discharged through the only path --- the parallel R. This parallel R and C is also connected to the MOS's "gate"(MOS's control terminal) and "source" (which is grounded). A MOS transistor has a threshold voltage that could be 1V to a few volts. When voltage on C is much higher than MOS's threshold voltage the MOS is turned on, and when much lower MOS is turned off. In the transition, the voltage on C is from slightly higher to slightly lower than threshold voltage, MOS will act like a variable resistor that fades the LED. So the slower R and C discharge, the slower LED fades......
sure you can use a variable resistor to set different fading speed.

multiplexor

Cool, thanks for the explanation, it makes more sense now
I sent you an email with some pics of what i believe are mos transitors from my technics amp i took apart.


Thanks,
Frank