Cheap Car Stereo


[Chris Rybitski] didn’t really have any money to spend when the headunit in his car died. He did have a broken JVC CD player from a friend and decided to convert that into something hideous he could use in the car. The amplifier portion still worked, but the CD section didn’t. Unplugging the CD board kept the amp from functioning, so he cut off the bulky motors instead. The internal power for the player was already 12V so he powered it directly from the car. He added an old CDROM drive, made a wired remote for the controls and stuffed everything in an old Mac case. Once completed, he set it under the rear glass for everyone to admire.

61 thoughts on “Cheap Car Stereo

  1. He needs a voltage regulator since the voltage at a car’s cigarette lighter plug is *not* 12v. It can vary anywhere from 8 to 18v depending on the charge level and engine RPM while running.

  2. Must be a slow day on the hack-a-day tip line. This one really deserves the term hack, as in “hacked together”, see: poorly.

    On a side curiosity, what GM vehicle is that? I was going to guess Chevy Lumina, but the distance between the 3rd brake and the pillar seems too small, so perhaps Chevy Cavalier.

  3. ummm 18 volts is a little high (probably signs that the voltage regulator took a crap on you) :P

    14.4v should be the output of a working car alternator/regulator. But if it works when you plug it in, and not magic smoke escapes… cool :P

  4. that’s totally not ghetto at all.

    Also, this line:

    “I made a fancy bracket from alluminum to hold the wires inplace and keep them from pulling out.”

    actually had me lollin’. Fancy bracket indeed.

  5. Anything intended to work off of a car’s 12v line normally tends to have leeway in how much you can over volt it. Most go to 15v before stuff breaks, because most radios have internal voltage regulation circuits to divide voltage and stuff.

  6. True, 18 is high. That’s how high my gauge goes in my vehicle. It’s never gotten that high tho, so I don’t suppose you’d see that. I know it does fluctuate all over the place and it’ll give you headaches in your ‘tronics if you don’t regulate it.

  7. This guy is asking for some crack head / meth addict to break into this car to steal that fancy pizza box computer he has laying on this back window deck. I would pay money to see the look the pawn shop broker would give this guy when he tried to sell this “computer” to them for another hit.

  8. You can expect the voltage on a car’s supply to sometimes go as high as 50 volts briefly. Car regulators are not known for their good transient response. :-) Really car supplies are a kind of harsh environment.

  9. My girlfriend’s car lacks a cd player, something like this might be just the ticket. It’s funny that it never occured to me; I’ve hacked together little stereos using an old PSU, CD-ROM, and a couple of speakers before (held together with duct tape, of course).

  10. Hurm. I would say the voltage people are saying is way off. Ive done car stereos for years and rarely seen (un-intentionally) over 15 volts. They should put out 12 (from the batt) when off, and 14.4 when turned on. The cigarette lighter may drop some due to the low guage wire going to it. (and I wouldnt run more than a hundred watts or so through it w/o pulling another thicker wire). For the people saying that they are getting peaks of up to 50v, I disagree, youre having problems. If you do have voltages that high, fix your regulator before you fry everything in your car.
    Anyway… Nice to see, Thought about doin something like this w/ an old dvd player years ago (before they were so common in cars)… sadly a CD player will run you about 30 bucks these days used.

  11. The voltages people throw around refer to what you should be designing for, not anything one is likely to ever actually see in a car.

    Yeah, if you have 50 VDC on the rail, something is wrong. But when designing with such things in mind, it would be nice if your product were to survive it. It doesn’t have to operate well under such conditions, but not burning up is good.

  12. I think most everyone has missed the point of this hack… The idea was to build a stereo that cost absolutely nothing to make. This never claimed to be an alternative to your 2400 watt sound system. I was only intended to be better than what I had, wich was nothing…If you can do it better, then please, by all means, tell me how…

  13. I don’t get it.

    Why the massive board in the Mac case? The PC CD-ROM drive already outputs stereo audio, and you can build a simple transistor amplifier out of scrap components.

    If anything, this project is needlessly complex. The same result could have been done with electronics 1/16th the size and at a fraction of the time it took to throw this whole thing together.

    And yes, for zero cost.

  14. Ill tell you how,
    wire it into the damn car’s battery intead of a retarded ass third grade wire running from the back of the car to the cigarette lighter.

    All that creative inginuity just goes totally to shit when you are too inept to pull up a little carpet, some moldings and hook up a simple fusible wire to the cars battery. That way you wouldnt have to worry about any fluxuations from the lighter socket, and you still could use it for your cell phone, ipod, lighter etc. Any stereo guy would tell you that. if your goin to go through all that other trouble, why not take a little effort to do it right.

  15. #20 – What a complete ass.
    This is a “hack”. It’s not a professional stereo job you moron. It’s obviously a good enough “hack” to satisfy his needs, and he certainly didn’t make it to go into YOUR car to meet YOUR needs. Go look up the definition of hack, and while you’re in the dictionary, please do us all a favor and learn how to spell.

  16. hehe blaine — have you actually ever put a meter to a car battery while charging? Or any battery charging at a voltage higher than surface voltage?

    As for why not just make an amp? Well, why make one when you have one already? Making a new one just seems a little over complicated when all you have to do is use one already built with features you don’t have to build yourself. That is why the site is called hackaday, not buildaday :P

    50volts! I measured 1337 jigawatts! Yeah, I agree with #12 – if you get that high a spike, fix your regulator. I don’t understand why it is thought that the regulators don’t do a good job at their one job(regulating :P) – most car ECUs don’t like sensors that don’t have a good ground, having voltage fluctuations like the ones being described cause quite a bit of problems o.0

    Last but not least “no money at the moment I decided to make this temporary car amp..” Is it the best hack we’ve seen? No. Is it a decent hack that fits his needs? Absolutely. And because it works with whatever voltage the car is throwing at it, props to jvc…

  17. there are two definitions of hack usually used. one is in reference to something done elegantly, which is beautiful in its own way as to how it does a complex job. another is something that is thrown together in a slap-dash way, but does it’s job for what it is.

    i think this article satisfies both of those definitions, not everyone can make their own MP3 player the size of an ipod from scratch, so all you that want to bitch, shove off

  18. @ silver
    actually, in a vehicle application, twist and crimp tends to be the best option. soldering can create little solder balls that can and do break off with all the bouncing around, causing problems down the road (pardon the pun). twist and crimp (while not as pretty as soldering, but decidedly better looking and longer lasting than twist and tape) is more durable.

  19. Nice project. Reminds me of, was it 1985? All the radios were disappearing from cars in my parents’ town. Preferring bad sound over no sound, my dad took a really really cheapo old car radio. It didn’t even fit into the dashboard, so he timbered some sort of case for it. You know, a 27-drilled-holes-for-the-speaker type of case.

    However he made the mistake of nicely painting the wood – so some poor idiot still stole it.

  20. Hey.. the guy even went through the trouble of looking up how to hook up the power.. cept, it wouldn’t have mattered either way: the transformer drops the ac down to say 14 volts, but it is STILL AC. Hook the power up either way and the bridge rectifier straightens it out. You can see all the heavy diodes on the left of the connection he made for power.

  21. ohh yeah.. and the whole discussion about the Voltage Regulator: Put a cap (or a few) on both sides of the VR to keep the 5 volts constant, and whoever recommended the heat sync is right. With that VR, 12v in drops a lot of excess voltage as heat. 6 to 7 volts going in stays pretty cold. Even a strip metal works great.

  22. #20… The alternator charges well above 12VDC, so unless the battery is not connected to the alternator, you still have to deal with typically *up to* 18VDC. If you don’t hok it up to the alternator, you have to go out of your way to charge it, and the voltage can drop below 12VDC, which means it may or may not work.

    Regardless, even if the alternator output voltage were only 12VDC (which would be low for charging), the various electrical systems inject a lot of noise that by itself can wreak havok on some electronics. Voltage regulators (at least) are always a good idea when using car electrical system and even slightly sensitive electrical equipment.

  23. Blaine – You missed the whole point of this being temporary. What’s more inept “not doing it right” Or tearing up carpet and moulding (and potentially destroying your interior) even though you might not have ever done it before, for something you are only going to have installed in your car for a few months, and that looks like shit anyway (no offense to the builder and his Mac case ;) Not to mention the fact that if the guy had an Ipod, he’d be using it instead. I wouldn’t rip up my interior for anything less than an ACTUAL car stereo.. Tell me which one sounds more moronic!

  24. chris, hacks like this are indeed worthy of hackaday and yours was no different: You revived a besieged bit of wayward electronics — that is quite a bit more than most can say. You did so in a way that not only stretched the original functions of the device, but also added to its capabilities. That’s good by my book.

  25. 30.. ok.. you missed something.. The transformer takes the wall AC and drops it down, but it is still AC. YES the car produces DC.. the transformer was hacked out. HOWEVER, the transformer had pluged into the board and the first thing it hits is a bridge to convert AC (under 20vac) from the wall to DC..

    DC (from the car) going into a Bridge does the same thing: it converts DC to DC.. sounds stupid.. it simply means you can plug it in any way you want. Reversing the polarity would still work just fine.

  26. Chris: To help you visualize the power situation.. look here
    and read up on the full wave (its the diamond shaped one) When AC goes in, DC of a particular polarity ALWAYS comes out.. that is important in your case because AC phase shifts back and forth, yet you always have DC polarity on the other end. Thus, with DC (from the car) going in, its the same as ONE phase of AC.. and it doesnt matter which phase. One phase has two diodes always working and two never working.. get it the other way and the working and non working diodes just change places.

  27. Chris: the big black things with the white (or silver) stripes right by the fuse in the picture is the diodes of the bridge. A few notes: they drop about .7 volts each (varies), so with two always working, your 12 to 14 volts DC going in comes out at about 10.6 to 12.6 volts DC (which is perfect for the amp). This would be true (and properly polarized!) no matter if it were DC or AC. Also, in the link I gave you, the arrows are confusing. They represent ELECTRON flow. dont look at them. Instead, look at the symbol for the diode. Its an triangle with a bar on it. Positive voltage goes in the direction the triangle points. when Positive voltage attempts to go backwards (reversing the leads), it hits the bar and is blocked.
    Great hack by the way. Too bad you cant play “oregon Trail” on it though ;)

  28. For those of you that think the voltage in your car never gets to 50V, consider this.

    If you behave, and your car is reasonably new, it probably doesn’t.

    But the voltage can go really high if someone decides to disconnect the battery while the engine is running (google “load dump.”)

    Jump starting and possibly battery chargers can also cause big spikes.

    And if the ground straps between the engine and the car body get loose, this can also cause huge spikes.

    There is a good reason that most quality automotive electronics are designed to withstand over 40V.

    But, for the purpose of this hack, it doesn’t much matter. He never intended it to resemble “quality automotive electronics.”

  29. Most cars produce ~14v dc to charge the battery while on. This is what the alternator does. (Note: Alternators produce AC power which the car’s electrical system then changes to dc anyway. A generator produces dc power.) Also, most cars ciggerate lights are connected to the battery thru 2 fuses. No point in connecting it to battery unless the power requirements are insanely high. This can be proven since you can connect a ~14v dc source to the ciggerate light to jump start it (Which is safer since almost noone connects the negative cable to a chassis ground like they should)

  30. OrbnLgnd… what the hell are you talking about? there’s not AC being used in this project at all. 12VDC from the vehicle’s electrical system, and then 5VDC going to the CD-ROM drive through the 7805.

    Unless I’m missing something?

  31. 39: Correct. There is no AC at all in the project, Only 12 volts DC. However, the components on the amp from the ORIGINAL AC circuit were designed to provide DC voltages to the amp from an AC line. With these components still in place, it will not matter which direction the car battery is hooked to the amp, the parts from the old AC circuit will straighten the voltages out.

  32. My bad for telling the kid he did something the right way (even if he didn’t understand why yet).

    Forget all about AC. Look at the link I gave. Go half way down to the part that says “Full wave Rectifier circuit (bridge design). Forget about the arrows on the drawing.

    Look at the Supply on the left (circle with a wave in it). Normally this is AC, but ASSUME that it is the car’s power supply (DC). Now, the first drawing with arrows on it shows what happens when the battery has the positive lead going into the top of the bridge. Notice the positive voltage goes through the diode on the right and comes out at the Positive pin of the bridge. The Black diodes are the active ones in this case (allowing voltage to pass), and the gray are inactive (blocking voltage from passing through).

    The Next drawing shows what happens when the battery has the positive on the bottom. Notice that the positive voltage would go up from the bottom through the right diode and end up at the same place.

    Positve will ALWAYS come out the right side of the bridge, and negative on the left, no matter which direction the battery is attached to the top and bottom.

    If that doesn’t clear it up for everyone, I give up ;)
    (I DO admit perhaps my first couple posts on the subject might not have been all that clear.)

  33. #38: I see what you are saying. I’m not qualified in electronics, but I do understand a few things aout it I’m thinking 50VDC would be more typical in 24VDC or higher systems than in a 12VDC system. Semi trucks and some boats commonly use 24V+ systems, and some electrical equipment runs off of that.

    My guess on the why is due to the sudden change in load, the regulator increases the voltage in an attempt to maintain the balance until it cuts off, thus creating a surge. Dunno.

  34. Sux when people write in comments about how they think the hack is not worthy. Instead, why not post your hacks and see if you can get on the main drag.

    Anyway, this is relevant. It’s hacks like this that teach people valuable lessons. Dude probably refined his soldering skills a little bit, learned how to cut up a pcb, learned how to cut a case up and bolt things in it, etc. He defined a problem, took some scrap parts and implimented a solution.

  35. “My guess on the why is due to the sudden change in load, the regulator increases the voltage in an attempt to maintain the balance until it cuts off, thus creating a surge.”

    Kind of. An alternator and regulator do not regulate voltage in the same way as normal integrated circuit regulators, such as the 7805 in this project. The way an alternator works is that the regulator changes the current through the field coils to change the amount of magnetism produced by those coils such that the armature generates the necessary voltage no matter what the engine speed or electrical load is. In an ideal world that is.

    But what actually happens is that those field coils have a lot of inductance. Inductance resists changes in current flow. Therefore you can’t change the field current instantly when a big load, such as the battery, is disconnected. There is a fraction of a second where even after the regulator has tried to reduce the current flow to the field coils the actual current doesn’t drop much. Durning this period you have way more field current than you need, so the voltage generated by the alternator shoots way up from where it is supposed to be.

  36. If sufficiently heatsunk, is a 7805 regulator all that is necessary to produce fairly clean and stable 5V from a car cigarette lighter socket? Or do you need all kinds of extra fancy capacitors and zener diodes and stuff?

    I built a car power supply with basically just a fuse, 7805, heatsink and fan, for a GPS and iPaq, but now I’m slightly worried that I might be giving them a really nasty feed. Don’t have a storage scope unfortunately to look at the waveform. Any advice or rules of thumb?

    Oh, the car is kind of crappy and old so it’s safe to assume there’s little or nothing in the way of onboard smoothing for cigarette lighter accessories.

  37. “The point is if the voltage in my car ever got up to 50 volts, then my stereo wouldn’t be running any more”

    That’s not necessarily true. Maybe 50V is a bit high, but if the designer of your stereo had any clue what he was doing, it is designed to take voltage spikes into the 40 some volt range.

    And like I said twice before, it’s not just a faulty regulator that causes spikes. Spikes can come from disconecting the battery while the engine is running, charging the battery, jumpstarting the car or jumpstarting someone elses car, loose battery cables, loose ground straps, and a few other things I’m probably forgetting.

  38. Now, after posting that, I see that I was replying to Chris Rybitski, the writer of this hack.

    Before I noticed that, I assumed you were talking about a commercial car stereo, not the system in this hack. Real commercial car stereos are designed to take voltage spikes in the 40 volt range.

    Your hacked up system isn’t designed to do that, but sometimes you might get away with it for a long time. Protection circuits aren’t needed until something goes wrong.

    So don’t be surprised if it quits working someday after you jumpstart someone’s car or a battery cable comes loose.

    But don’t worry about it either. This is a system you hacked together out of free parts. It’s OK if it isn’t designed perfectly. :) And even if it does break, you learned something in the process, and you’ll have an excuse to do it over again and fix the things you’ve learned how to do better the second time around.

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