Originally Posted by Chimmy3

would a 9v battery work to charge the unit before hook-up?

Originally Posted by Kong

yes, but it might drain the 9v battery

Originally Posted by Kong

No, I didn't get it. Please resend.

Originally Posted by Kong

Dude, you can't use regulator. You will loose power. For example, if your car need 3A of current and you have a 12V regulator, you will lose (14-12)*3=6W of power at the regulator. If there is no ventilation around the heatsink, the regulator will heat up very quickly and fail.

The cap works as the powe supply filter, it reduces the voltage ripple so that the overall electric system has less noise. Many part in the car relies on electrical sensor, and noise cause error in sensor readings -> error in fuel/air ratio. The cap indirectly reduce error from noise coupling through power supply.

Originally Posted by Kong

It only help supplying transient current for less than <100ms, you will not notice it, but the computer will. It mostly acts as a filter. In electronic stuff, steady power supply in very important. Ripple in power supply also cause instability in some amplifier (I mean sensor stuffs, not audio). Let's say.. it makes a better environment for electronic systems to operate.

Yes, and No. Typicall, a large cap has smaller ESR (equivalent series resistance) and has higher ripple current, which is good . It is bulkly and difficult to package. It's frequency response is limited. Also, its price (capacity/$) is more expensive than the small capacitor.

I use 16V caps because I can get higher capacitor values. It is more compact and cheaper ;) . Yes, the battery is running at 14V and It won't go above that, unless there is something wrong with the alternator and the battery will be damaged anyway. I was first thinking about using the 25V caps, then I find justifications to use the 16V caps instead. The capacitor can withstand voltage ripple of more than 16V, but it cannot withstand "steady" voltage of more than 16V, so it should be safe.

The main reason I make this myself is that I want to know if it works without spending too much money on it.

Originally Posted by Kong

when you start the engine, the voltage actually drop slightly. You can see that the lights are dimmer when you start the car.

Originally Posted by Kong

10,000uF for the electrolytic caps and 100uF for the ceramic caps.

Originally Posted by Scott17

^^^^ Get off the pipe!

Originally Posted by ufo

hi kong, i haf jus diy using ur idea,well it seems tat , there is no such 100uF ceramic caps in the market., i wonder if u haf mix up wit the caps types.oh ya, about the DIy, i use 100 uf electrolytic caps n it doesnt work at all, when i turn on d head lamps it was ok but when i switch on the signal light, the light blinks follow the signal light, why is tat so, anyway the voltage also drops, not consistent at all, wel,,, as i cited b4, i dun tink merely CAPS will do all the wonders as a V.S. any advice ???

Originally Posted by Kong

Sorry for late reply.

The electrolytic caps might have been broken. Did you have the right polarity? The electolytic cap has positive and negative terminals. If you switch the terminal and connect to battery, it will die. When it is broken, it make a short connection to your battery. It could have been the ceramic capacitor, make sure that it is rated 16V or above.

I bought caps from Digikey.com . you can also use several ceramic capacitors combined in parallel.

I have been using it for 4 months now and it works just fine. I made several sets for my friends and no one has problem with it.

If you need help immediately, pm me. I haven't visit the forum for quite a while.

If you guys are around DC, I have a set unused. We can meet and try it out.

Originally Posted by ufo

hi kong, my diy v.s also include a fuse, so if anything does happen , the fuse will blow 1st, i did check d capacitor after i connect it, looks ok, no leaking n no visible damage caps at all, i tink it might b the car problem, some leakage ... howw do i post my V.S??[img][/img]