A have a fried drill with still good 14v 1.7 ah batteries and charger, and a unused amplified computer speaker sistem (small cheap stuff) with the real output of like 2 or 3 rms watts. Thinking of converting it into portable speakers and powering it with a 14volt battery. Just like those makita site radios. I think the circuit needs 9volts im not sure will have to check if much less than 14.4v will reduce current with a rezistor, but will it work?[/list]
A silly little project
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I am sure it will work but of course you need to drop voltage. If under 2A is required a 7809 voltage regulator will likely work as the current required goes up then the voltage dropping becomes more of a problem.
To reduce heat in 7809 likely need to feed through a resistor so at max output the 7809 does not have to dissipate the heat.
Because power will not be consent a simple resistor will not work. Using a potential divider may work but will waist power.
To reduce heat in 7809 likely need to feed through a resistor so at max output the 7809 does not have to dissipate the heat.
Because power will not be consent a simple resistor will not work. Using a potential divider may work but will waist power.
Have a look at in-car dc-dc converters, the nominal 12V input should be ok up to the 14V battery voltage, & it will give you a nicely regulated output (complete with the right plugs - always a bonus!).
Right, as im a total noob when it comes to electrics, I will have to ask, what is the difference between a resistor and a voltage regulator and how much does it cost? I still have to buy a soldering gun and a multimeter to start the job. Since I want kickass sound coming from the box, I will upgrade the bass speaker also, and build a proper enclosure which will accomodate everything, bass speaker, left and right speakers on the sides, amplifier circuit and a compartment for the battery. I want to build something that is just as good as a makita radio, but without the radio part, will use my mp3 player to make noise. Anyone knows how powerful the amp in those radios is? Dont believe it 100w.
How about the drill, has it got a voltage regulator?
You mean constant?
How about the drill, has it got a voltage regulator?
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you might be better using a cheap car stereo as the amplifier; it should take car-battery type voltages. Most have a line in for an MP3, or can be modified.
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A voltage regulator of the 78 and 79 series are three wire semiconductors which will reduce the voltage to a reasonably smooth output of up to 2 amp and get rid of the excess energy as heat. Not very efficient but cheap. The last two numbers are the voltage so a 7809 will be 9 volt from negative rail and a 7909 will be 9 volt from positive rail. Click here they are around £1 depending on current designed for.
Normally some other components will be used to smooth the output but likely you will not need them.
The problem is as you increase the power required these become unsuitable and the regulator has to be more complex. These complex regulators can be what is referred to as switch mode and the heat generated is far less. But so complex to build they are not worth doing as a DIY project one just buys one.
Clearly the idea was to use something existing and unless the cost is very low it would be just as cheap to buy the right size battery pack to start with.
As a fun project then great. But since you don't even have a soldering iron to save money just not worth while.
The other cheap option is a potential divider. This is basic two resistors in series. So taking easy numbers a 9 ohm resistor and a 5.2 ohm resistor in series across your 14.2 volt battery will give a max of 9 volts across the 9 ohm resistor. However as you draw current the voltage will drop so if the device used 1 amp the volts will drop to 4.5 volt it will also use 2 amp from battery even when only 1 amp is supplied to device. These are not exact but close enough values for you to understand.
Now the other method of just a supply resistor when using no current the volts would be 14.2 so could burn it out but when at full power could drop to 4 volt and so in real terms not usable.
If your idea is to play and learn then great I am sure we will all help. But if wanting to save money forget it. Buy a 9 volt battery and charger instead.
Normally some other components will be used to smooth the output but likely you will not need them.
The problem is as you increase the power required these become unsuitable and the regulator has to be more complex. These complex regulators can be what is referred to as switch mode and the heat generated is far less. But so complex to build they are not worth doing as a DIY project one just buys one.
Clearly the idea was to use something existing and unless the cost is very low it would be just as cheap to buy the right size battery pack to start with.
As a fun project then great. But since you don't even have a soldering iron to save money just not worth while.
The other cheap option is a potential divider. This is basic two resistors in series. So taking easy numbers a 9 ohm resistor and a 5.2 ohm resistor in series across your 14.2 volt battery will give a max of 9 volts across the 9 ohm resistor. However as you draw current the voltage will drop so if the device used 1 amp the volts will drop to 4.5 volt it will also use 2 amp from battery even when only 1 amp is supplied to device. These are not exact but close enough values for you to understand.
Now the other method of just a supply resistor when using no current the volts would be 14.2 so could burn it out but when at full power could drop to 4 volt and so in real terms not usable.
If your idea is to play and learn then great I am sure we will all help. But if wanting to save money forget it. Buy a 9 volt battery and charger instead.
Of course that I want to learn! And thsnk you for the well detailed reply. I like doing fun projects like this all the time, mostly audio related stuff since im an audiophile nut, but one of my projects included installing keyless lock on my shed, used a central locking motor off of some car, along with the remote and receiver, connected to a 12volt tranformer, with the mains to the shed having a secret switch in the house, so even if you were a guest and had the remote, still couldnt dig through my shed without powering up the transformer first. Of course it was pretty easy but still had to figure out and fabricate a proper locking mechanism that was sure not to jam. All that work, to make sure my gardening tools do not get stolen because I paid like a whole 25 quid for all.
So yeah, im always willing to learn.
Tell you what. Im gonna go ahead and find out the circuits operating voltage first, then I start making the enclosure, and build a connector for the battery so it can pe plugged and unplugged just like it was with the drill. And when everything is done and is time to solder things together, thats where probably ill be needing step by steo guidance.
Ps. If I wanted to save money, couldve just had the batteries and charger sold since its dewalt nimh in very good condition plus the drill for spares, and bought a makita radio. So no, I actually want to make my own cordless portable speakerbox.
Just one question at the moment because im a bit confused now. I thought that these batteries supply a constant voltage til they run out of juice and need charging. And now I find out that the voltage can drop to a third. Well how is the circuit still going to amplify with a third of its operating voltage?
So yeah, im always willing to learn.
Tell you what. Im gonna go ahead and find out the circuits operating voltage first, then I start making the enclosure, and build a connector for the battery so it can pe plugged and unplugged just like it was with the drill. And when everything is done and is time to solder things together, thats where probably ill be needing step by steo guidance.
Ps. If I wanted to save money, couldve just had the batteries and charger sold since its dewalt nimh in very good condition plus the drill for spares, and bought a makita radio. So no, I actually want to make my own cordless portable speakerbox.
Just one question at the moment because im a bit confused now. I thought that these batteries supply a constant voltage til they run out of juice and need charging. And now I find out that the voltage can drop to a third. Well how is the circuit still going to amplify with a third of its operating voltage?
http://www.google.co.uk/search?q=electronics+101
http://en.wikipedia.org/wiki/Resistor
http://en.wikipedia.org/wiki/Voltage_regulator
I would strongly advise a soldering iron instead.
I've always liked Antex.
If you plan to make this a hobby,and not a one-off, you might as well start off with a 660 TC or 690 SD - look for bargains on eBay
See the discussion here: //www.diynot.com/forums/viewtopic.php?t=26282 It's a few years old, so specific model number advice may be obsolete (and prices will be higher), but the generic advice is still sound.
Will the amp(s) in these little PC active speakers cope with that?
How will you connect different bass drivers to them? Do they even have separate drive units and crossovers?
If they do, will the characteristics of the crossover match the new combination of drive units?
What sort of speaker enclosure design will you go for?
Do you understand the pros & cons of different types, and do you know how to design and construct them?
Seriously - the phrase "running before you can walk" is really coming to mind here.
What sort of cable did you use?
How did you install it, and provide the necessary mechanical protection?
What size was it and what protective device rating did you use?
What testing did you do before you put it into service?
Did you apply for Building Regulations approval?
Ban all sheds, thanks for your first reply. As for the box, these are crappy little speakers anyway. Not worth doing any calculations, just slam one in, sounds about right-leave it, sounds like junk-replace it. The enclosure will be sealed since I dont like ported enclosures, and im gonna also get a bass driver for sealed enclosure. Current one is ported.
As for the second post, I just used some cable from some old christmas tree light. I installed it overhead and no necessary mechanical protection was needed because I cant fly anyway and no one in the house can. Before I put it into service, I just gave the remote to the neighbors kid to test it one morning, he played all day locking and unlocking it, and since at dawn it was still working, I thought it has been tested enough. So I wanted to go and get someone from the building regulations to approve it, but santa clause came and stole my cable (i left the lights still connected to it).
Next time i'll do a proper job, and also get a regulations approval, ok?
As for the second post, I just used some cable from some old christmas tree light. I installed it overhead and no necessary mechanical protection was needed because I cant fly anyway and no one in the house can. Before I put it into service, I just gave the remote to the neighbors kid to test it one morning, he played all day locking and unlocking it, and since at dawn it was still working, I thought it has been tested enough. So I wanted to go and get someone from the building regulations to approve it, but santa clause came and stole my cable (i left the lights still connected to it).
Next time i'll do a proper job, and also get a regulations approval, ok?
I'm sure you think it's very funny to joke about electrical safety.
I think it makes you a complete ****.
I think it makes you a complete ****.
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And posts like that make you look like a complete arse BAS.
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Perhaps if the OP needs a voltage converter then a kit may be preferred so there is no need to design it, just follow the instructions.
http://www.quasarelectronics.com/3060-universal-power-supply-board-for-78xx-regulators.htm
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Perhaps if the OP needs a voltage converter then a kit may be preferred so there is no need to design it, just follow the instructions.
http://www.quasarelectronics.com/3060-universal-power-supply-board-for-78xx-regulators.htm
So when we joke about safety items when we are at a safety seminar, does that make myself and my colleagues the same?
If you're an audiophile nut then why mess about amplified computer speakers? Get yourself a tripath amp off ebay for about £20. It will run off the nicad battery happily for several hours and they have an amazing kick.
It's just a phase he is going through
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