Author Topic: What is the best way to boost voltage (from 12v) (Read 14557 times)

cepa · « **on:** November 10, 2012, 10:35:33 pm »

Here's the thing. I have a portable audio amp that runs off 12v lead-acid battery. I feel that it is time for an upgrade, but I have one limitation, the battery. I want to boost the voltage from it. The most ideal would be around 24 volts, but any improvement would be appreciated. My amp draws around 1-2 amps at loudest settings, but I haven't tested it accurately. My amp can handle 24 volts, so no problem there. Since I am a complete newbie at power supplies and a beginner in electronics, what would be the best solution, if there's one?

Also I can't go out ant buy a new battery, and the project should cost around 10 euros, so no expensive solutions.

Thank you for your help.

Psi · « **Reply #1 on:** November 10, 2012, 10:39:53 pm »

So you want to boost 12V to 24V at 2A ?

cepa · « **Reply #2 on:** November 10, 2012, 10:40:41 pm »

In a nutshell, yes.

IanB · « **Reply #3 on:** November 10, 2012, 10:45:33 pm »

For $10?

cepa · « **Reply #4 on:** November 10, 2012, 10:47:00 pm »

Euros. I am not aware of the costs of such things.

Psi · « **Reply #5 on:** November 10, 2012, 10:48:03 pm »

Kemo made a 6-14V input 11-26V output 2A boost module, not sure if they still do.
Jaycar used to stock it.

Bit outside your budget though.

http://www.conrad-uk.com/ce/en/product/190531/VOLTAGE-CONVERTER-6-14-VDC-11-26-VDC

cepa · « **Reply #6 on:** November 10, 2012, 10:54:31 pm »

Yea, that one is. How about this thing? http://www.conrad-uk.com/ce/en/product/191060/DC-voltage-transformer-kit/2412120&ref=list

Can I make one myself, I do know how to etch pcbs and solder quite well. I can also use CAD software to design my own pcbs if need be.

IanB · « **Reply #7 on:** November 10, 2012, 11:00:56 pm »

Quote from: cepa on November 10, 2012, 10:54:31 pm

Yea, that one is. How about this thing? http://www.conrad-uk.com/ce/en/product/191060/DC-voltage-transformer-kit/2412120&ref=list

Can I make one myself, I do know how to etch pcbs and solder quite well. I can also use CAD software to design my own pcbs if need be.

That kit is within your price range. Why don't you just get that one and also get the optional big heat sink to go with it?

cepa · « **Reply #8 on:** November 10, 2012, 11:06:19 pm »

I don't think they ship to where I live, also it's more fun to build something myself, rather than buy something that is already made

Mechatrommer · « **Reply #9 on:** November 10, 2012, 11:23:17 pm »

the components look more sensible, 4A spec, USD7 or around GBP4, no need tinkering...
http://www.ebay.com.my/itm/DC-DC-Max-4A-4-5-32V-5-60V-12V-24V-step-up-BOOST-converter-power-regulator-/160905988988?pt=LH_DefaultDomain_0&hash=item2576be8b7c

or this, still within budget. you get what you pay...
http://www.ebay.com.my/itm/Brand-New-12V-24V-3A-DC-DC-Step-Up-Boost-Voltage-Converter-Module-52Khz-/290735640296?pt=LH_DefaultDomain_2&hash=item43b131cee8

if you need to diy maybe this...
http://en.wikipedia.org/wiki/Boost_converter
http://www.ti.com/download/trng/docs/seminar/Topic_3_Lynch.pdf
dmm, oscilloscope, lcr meter and lot of time

Uncle Vernon · « **Reply #10 on:** November 11, 2012, 12:41:22 am »

Q: What is the best way to boost voltage (from 12v)

A: At the same current drain and expected run time the best and most efficient option is another battery in series.

cepa · « **Reply #11 on:** November 11, 2012, 05:20:16 pm »

Another battery is out of the question, since lead batteries are heavy, and my amp is portable, so I want to minimize the weight.

Currently I am looking at the MC 34063 chip. If all else fails I will buy one of the commercial products, although building something myself would be more fun.

mariush · « **Reply #12 on:** November 11, 2012, 05:57:24 pm »

The inductor you'd probably have to use with 34063 for 24v @ 2A would be quite expensive. You may be able to get the overall price lower if you choose a better switching regulator.

Even MC34167 would probably be better.... or MIC2171 perhaps....

cepa · « **Reply #13 on:** November 11, 2012, 06:08:06 pm »

Since I am not aware of these switch-mode regulators, is there a list of some sorts that would fit my application?

mariush · « **Reply #14 on:** November 11, 2012, 06:14:00 pm »

I'm not very experienced with these devices, but it's common sense the lower the switching frequency, the higher/bigger the inductors have to be, especially for the current you need.

The ones I mentioned run at 72kHz for the first, 100kHz for the second, while the classic 34063 runs at 52kHz (I think).

For the 34167, the formulas are similar to the ones for 34063 so if you watch dave's video you then just need to adapt the match for the higher switching frequency. For the MIC2171 chip, check the datasheet for the formulas or if they're not listed search for "2171" made by other companies, their datasheets may have the formulas.

cepa · « **Reply #15 on:** November 11, 2012, 06:16:12 pm »

Dave has a video for this? Damn, how could I have missed this, going to watch it ASAP. Also I checked, inductors are reasonably priced at my local store.

mariush · « **Reply #16 on:** November 11, 2012, 06:28:59 pm »

Yeah, they may be, but pay attention at the currents. For 2A, you may need inductors rated for 6-10 A, even more. Not sure how accurate it is, but an online calculator for mc34063 says the peak current to get 24v @ 2-2.5A is 13A, and such inductor on digikey is 3-5$, even more.

cepa · « **Reply #17 on:** November 11, 2012, 06:46:29 pm »

After checking the datasheets I found out that I will only have to boost the voltage to 18 volts, since my amp only handles 18 volts.

Zero999 · « **Reply #18 on:** November 12, 2012, 12:07:06 pm »

.Is this a home made amplifier?

What configuration are you using?
If it's single ended You can theoretically quadruple (in reality you're looking at triple) the power output by switching to a bridge.

What's the impedance of the speaker?

cepa · « **Reply #19 on:** November 12, 2012, 03:33:18 pm »

Yes, a home made amp, using the TDA2005 chip. The speaker impedance is 4 ohms.
And what do you mean, single ended?

SeanB · « **Reply #20 on:** November 12, 2012, 06:23:33 pm »

It already is a bridged amplifier, or at least it is if you are getting more than 5W out of it. I have built a voltage doubler using one, where it was made to oscillate and each half then drove a diode pump with 2200uF capacitors to give a 20V rail from 12V input. It worked, but ran a little warm unless heatsinked well, but gave 2A output.

mariush · « **Reply #21 on:** November 12, 2012, 06:56:01 pm »

Hmmm.. have you actually read the datasheet for TDA2005?

http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000124.pdf

18v is the maximum voltage recommended. If you look at the graphs with distortion information and everything else, you may notice you shouldn't really give it more than 16v. But even so, with 12v input it should do about 4-5 watts, with 16-17v it would do about 8w - are you sure you wouldn't be satisfied with 12v and about 5 watts of output?

It looks like a cheap IC to me, with modest specs. I'd rather go with a TDA2040 or something similar. Here's the TDA2040:

http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000130.pdf

You can configure it to run in a pair in bridge mode (and theres the circuit in the datasheet) and it can also run with up to 40v, so you could just grab one of those 24v power supplies or a 19v laptop charger and be done with it.

cepa · « **Reply #22 on:** November 12, 2012, 07:58:21 pm »

I don't want to rebuild the amp again, so not really a solution. Also all I knew from the beginning that this won't be a huge improvement, but any improvement is an improvement.

mariush · « **Reply #23 on:** November 12, 2012, 08:07:21 pm »

Still, you could get one of those 19v laptop adapters then, and just put two diodes in series to drop about 1.4v. May be cheaper than using a switching regulator, plus inductor, plus protoboard or whatever, plus you get less ripple and more current than 2 amps.

cepa · « **Reply #24 on:** November 12, 2012, 08:40:56 pm »

I will try digging around my junk or just go to the flea market and find something there. As far as I understand, I should be looking for one of those 12 v to 18 v car adapter things.


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Author Topic: What is the best way to boost voltage (from 12v) (Read 14557 times)

Uncle Vernon

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