yet another DIY Boombox newb

[JeremyF4i]

Howdy everyone,
I've been reading through all the amazing knowledge and talent on this board and decided to register and try you guys out for an answer to my wiring question.

First I'll explain my thought process and plans, then the question/s.
Thanks in advance.

Project: portable boombox (consists of 12v car stereo, 4 speakers, power supply and battery).


- I'll be using a 12v 30a switchable power supply to convert 110vac to 12vdc.

- I also plan to use a 12v 9ah battery so it will be mobile and able to play at camp sites and such.

- The battery will recharge via a battery charger/tender that I will plug in when needed (and eventually a small solar panel, and power controller for off-grid charging). These will obviously not be a strong enough charge to maintain the battery while in use, but that's not my goal, so it's not an issue. I'll just use it and recharge when I need to.
.
Side note, the wire for the stereo to provide power to retain the memory/programming in the cd player will be directly wired to the battery. With this thought, I wonder how I will maintain a complete circuit for that, if I switch to the power supply feed instead of battery. (This may be answered with my question below, if the answer to that one is what I’m thinking it is)

Also, I was originally going to run the CD player straight off the battery and have the power supply maintain it but then it started getting difficult for me to figure how to keep the power supply from over charging the battery, other than manually monitoring it, which is why I decided on two separate systems. (you know. to simplify things. haha right)

- - With the two separate systems concept, I can't wrap my brain around ‘how to wire the switch between the two systems’. In a house, you have a ground, in a car you have a ground (anywhere on the frame or good metal attached to the frame).
In this system.. ???
?? - Do I connect the 12v negatives of the battery and power supply together as one circuit, and then wire in a toggle switch that would have the battery 12v+ on one side and the power supply's 12v+ on the other side?
Or do I need to keep the negatives of each system (Battery and Power Supply) separate from each other as well?

Thank you.

 

[Bob Richards]

A car is totally isolated from earth ground (by its tires), so there should be no conflict. Answer to last question: Yes.

 

[infinia]

no you do not have to wire the 2 batteries negatives . Usually the RCA connectors have some ohms connections to their power grounds, so be aware of this when connecting the two inputs together. This may become an issue when connecting up the AC chargers. A ground loop can be created. If you decide to listen whilst charging both batts it may be better to connect the two ground powers with a heavy wire.

 

[infinia]

a 12V battery tender is nothing more than a small regulated power supply at 13.6-13.8 VDC. I often use higher current 13.8V regulated supply to power both the device (stereo) and maintain the battery. This technique is a poor mans UPS system, when the battery is uncharged it's trickle charged at the lower voltage so it takes longer to charge up than regular bulk charger at 15V. very useful indeed. Buy a cheap cheerful SMPS ~40-80W with current limit and voltage adjustment. Save wear n tear on the batteries, if you find that most times yer listening near power sources.

 

[JeremyF4i]

no you do not have to wire the 2 batteries negatives ..

There is only one battery.

Incase it didn't come across correctly, I will have a 12v 30a power supply when near an outlet.

It will have an battery for when I'm not near Ann outlet.

It will have Ann battery tender/charger quick connect wired to the battery to plug in an nod charge when near an outlet.

I need to figure how to wire the switch that would annually me to switch to either power supply feed, or battery feed to the radio.

Side note, I will need to hook up the wire to the battery that maintains the memory/programming in the radio. I know what wire this is, but since I'm not sure how to wire the switch (answers - side of the circuits), this is also a question.

My thoughts:
If I am supposed to connect both the negative wire from the power supply and the negative wire from the battery to the negative wire of the stereo, then this answers my question of how to wire the toggle switch, and also answers my question of how to wire the "memory" wire of the radio along with the, as the negative wire of the radio would always be connected to the battery per se.
And in this case the + side of both power sources would connect to each side of the toggle switch so only one or the other can ever be on.

Could someone more familiar with this stuff (than me) confirm this or correct it? thank you.

 

[Bob Richards]

Your idea sounds right. Tie all the negatives together, and wire the switch like you said. When the switch is in between positions, the stereo with memory will get no voltage (for milliseconds), so the memory could be lost (maybe not likely). The way to fix that (if it's a problem) is to put a large electrolytic (maybe 100uF) from the switch wiper to ground. The cap will store charge (and a little more filtering never hurts), and discharge over a period of time (maybe several seconds), so voltage will be maintained for the memory function while the switch is switched.

When charging a battery, I believe it's the current you want to regulate, not the voltage. I believe that the voltage needs to be at least what the battery is rated at.

 

[JeremyF4i]

Your idea sounds right. Tie all the negatives together, and wire the switch like you said. When the switch is in between positions, the stereo with memory will get no voltage (for milliseconds), so the memory could be lost (maybe not likely). The way to fix that (if it's a problem) is to put a large electrolytic (maybe 100uF) from the switch wiper to ground. The cap will store charge (and a little more filtering never hurts), and discharge over a period of time (maybe several seconds), so voltage will be maintained for the memory function while the switch is switched.

When charging a battery, I believe it's the current you want to regulate, not the voltage. I believe that the voltage needs to be at least what the battery is rated at.

Thanks for the reply Bob, that's more what I'm looking for.
Regarding the memory of the stereo though, if all the negatives are tied together, the radio will always have the negative connection, for the positive side, no matter where the position of the switch is at, so I'll run the colored wire (orange maybe? Have to look again) to the positive battery terminal so it will always have have power. This would be similar to how it would be in a car so that should be good now too.
I think you answered what I was stuck on.
Thanks again
.

 

[JeremyF4i]

2nd post regarding car stereo boombox

Hey everyone,
I've decided to simplify my boombox a little and have another question.
originally I was going to build it with two 5.25" Clarions and two 6.5" Alpines but was wondering what it would sound like and whether it would be large enough to get bass with each speaker having a separate chamber. I found that I must've sold the Clarions in the past so I was going to use two 4x6" Pioneers that I have instead.
Problem with this is I don't much care for the look of this arrangement as opposed to 4 round speakers.

So, I decided today that I'm going to just build it with the 6.5" Alpines (SPS-1729) which will solve my "are the internal dimensions big enough" without making me feel the outside dimensions are larger than I wanted.
I'll either make the 4x6" Pioneers in separate boxes that can be plugged into speaker terminals on the back of the boombox or some other speakers. either way it opens up my options for that part of things.

My question is this.
Is it beneficial or worth it to port the enclosures for the 6.5" Alpines?
They will be built into the boombox but will be separated inside from the head unit, battery, PSU, and will be insulated as well. (the main reason I decided to put them in their own 'chambers')

If not worth porting, great as that takes another hurdle out of my plans.
If it is worth porting them, does anybody have any ideas/suggestions of dimensions or the port? I'm thinking the square port idea rather than the round tube.
each speaker enclosure will be roughly 10" x 9" x "7 (or 8").
I haven't worked out the new dimensions since removing 2 speakers from the plans, so I"m not definite yet.

I do know that the actual dimensions are necessary to figure out the port but my question is mainly is it worth spending my time to figure out specs of porting or better off to just go with sealed? Thanks.

 

[JeremyF4i]

Dual power source Boombox update

howdy,
it's been several months since I completed the build, and things have been great up until recently when I was on my workbench multiple days straight and had removed my battery tender (since the battery was fully charged.
I was running the boombox off of the PSU so no worries right?

all of a sudden it just cuts out. I confirm there's still power through the power supply, radio still retained memory, etc.. but when I would turn it back on, it would make a noise like it was going to play, then back off again.
I flipped on the Display for the battery voltage and found it had dropped.

yay, time to troubleshoot.

as a refresher:
I have a power supply to run off 120v and battery for when away from an outlet.
the + of both power sources are connected to a 3-way toggle switch. (on-off-on)
the - of both power sources are connected together at a ground block.

the memory (and possible illumination?) are wired to the battery's + so it retains settings/stations.

if I run it off battery and flip the toggle switch over to the power supply, when the power supply itself is turned off, the radio will continue to play, however if I turn the radio off, flip the toggle switch to power supply and turn radio on, it plays, if I flip the toggle switch to the middle position (off), the system shuts off.

so, apparently going from psu to off is off, but going from battery to off or to off power supply, the radio continues to play.

any ideas? I"m guessing it's related to the memory power that's transferring through the radio once it's already turned on?

I'll be going through the wiring again to make sure I have things hooked up correctly, but I'm guessing that's going to be the determination.

<a href="http://s876.photobucket.com/user/jpalmi/media/Boombox/20160602_023128_resized_zpslafyrir4.jpg.html" target="_blank"><img src="http://i876.photobucket.com/albums/ab329/jpalmi/Boombox/20160602_023128_resized_zpslafyrir4.jpg" border="0" alt=" photo 20160602_023128_resized_zpslafyrir4.jpg"/></a>

 

[horst303]

Maybe try and rewrite your query in the most precise and concise form you can, because I'm having trouble untangling this, judging by the lack of responses other people have had the same experience. And fix your image links of course.

 

[famax]

Maybe try and rewrite your query in the most precise and concise form you can, because I'm having trouble untangling this, judging by the lack of responses other people have had the same experience. And fix your image links of course.

no the lack of response is just because of people - i see it often on here hen there are new posts

 

[famax]

anyways, to reply this thread, you are battling with the wind here - get a simple UPS system. no need for a switch or anything then but a on/off switch. here is an idea,
12V 5A SW Power Supply Battery Backup UPS CCTV Security | eBay