Anyone actually suceeded in making a car amplifier?

[SkinnyBoy]

Just interested to know, because I have started mucking around with switchmode powersupplies again, and have FINIALLY managed to get it to actually do something.... that is, with 9 volts in, I saw 26 volts out.. I intend on using 2 transformers, one for each rail, and the feedback pin on the ICto get somewhere between 25 and 30 volts.. (+-)

anyway.. anyone had any sucess? THANX!

[sreten]

Home built switchmode supplies are a disaster waiting to happen.

JMO sreten.

[cm961]

I got the low power version one going from www.sound.au.com (Rod Elliot site). I produced about +15 and -15 from 12V input. However, the voltage sag was terrible, I think because my output inductors were too small. I plan on making a serious attempt at a higher power version. I think it can be done, and I don't think its that hard, but I do think that you really need to know what you're doing. Therefore I'm going to get a good book and read it (like I did with Sloan's amp book, which has become my bible so to speak).

It's a shame that my electrical engineering degree (of which I've got one more semester to go) doesn't contain any electronics. I found it funny that we cover basic op amp (inverting, non-inverting, followers, etc) theory in my fourth year electronics 3 course. If it wasn't for resources like this forum I'd be like my peers and have a 4th year electrical engineering degree, and know nothing about electronics.

Pete

[SkinnyBoy]

what are all these problems people always talk of? what is so hard about it??

I now have an adjustable +- voltage (adjustable from 20 to 30 volts) from the single transformer, its really too small to run an amp though, but I'll still give it a try..

[SkinnyBoy]

well.. the amplifier runs.... BUT!!! the rectifier diodes get TOO HOT!!

I am using the rectifier diodes from a couple of old computer powersupplies, they are the ones from the 5 volt rail... maybe they aren't rated at 30 volts... hmm.. anyway, they are on the same size heatsink as they were on in the computer powersupply, and should only be passing like 2 amps.... probably less actually, but the heatsink gets hot enough to BURN me.. any ideas? lol apart from that, the amp works... it was cutting out, then not coming back on for a while, but I think that may have been because the diodes were cooking..

EDIT: I am NOT using low ESR capacitors at the moment, would this be the problem? thankyou...

[SkinnyBoy]

IT BURNS!!!

[fr0st]

A built a Elliot SMPS (SG3525 based) and it worked perfectly. I had an initial problem of to little primary turns but after that was sorted I got +-35v very stable.
I ran two p3a's off it and it sounded great (except on my friends car that had the regulator removed...). It only got cranked to about 25w rms each amp coz his speakers where quite poor and my bedroom ones are only 30w rms.

any ideas?

Onsemi make 200a ultra fast diodes for sample I've got enough to make my next beasty amp (hoorah for kilwatts )
They make smaller ones also if your feeling light hearted. If you can't get low ESR caps just paralell lots of 1000uf caps and you get the same results (or lower if you only using like 2200 uf worth)

I think I'm to eager to use dual 8.5cm ferrites

[SkinnyBoy]

I don't like the rod elliot circuit.. too many components... lol

these are super duper mega fast diodes... lol

this is the circuit I am using..... (before the mosfets and transformer and stuff....)

[Immo_G]

Yeah i'm still designing mine, like i've got a schematic done fairly close to robs, and then trying to make a neat single sided pcb (not really possible). I've had some helpful hints from this forum, like the output inductor thing i haven't decided on yet, but i might try them if the voltage feedback fails to work.

[peranders]

Originally posted by SkinnyBoy
what are all these problems people always talk of? what is so hard about it??

Originally posted by SkinnyBoy
well.. the amplifier runs.... BUT!!! the rectifier diodes get TOO HOT!!

Originally posted by SkinnyBoy
IT BURNS!!!

Maybe you have given yourself a couple of answers....

Good, effecient, non-emitting SMPS is nothing for amatuers. It IS hard to build from scratch without knowledge or instruments.

It's not hard to build if you have a ready made pcb with good instructions but where are they...