Power supply
Posted by: mrm on 27 May 2003
Hi Guys,
One way or another we have all experienced problems with the mains supply. This forum has many posts regarding ways to clean the mains, and I have just come across another possibility, ( at least it is new to me) and would like an opinion of it.
What about powering from a 12V battery and a power inverter? Modern power inverters are much improved on models from only few years ago (or so I am told), makes such as Mastervolt (www.mastervolt.com), are less noisy and more stable in operation. Clearly a pure sine wave would be needed. Does anyone have any experience of using one of these? Would it produce a clean supply much the same as that produced by a PS audio power plant, but from a battery instead of the mains?
Inverters are much cheaper than Power plants, a pure sine wave 150W is approx £150-200.
Regards
Mark
One way or another we have all experienced problems with the mains supply. This forum has many posts regarding ways to clean the mains, and I have just come across another possibility, ( at least it is new to me) and would like an opinion of it.
What about powering from a 12V battery and a power inverter? Modern power inverters are much improved on models from only few years ago (or so I am told), makes such as Mastervolt (www.mastervolt.com), are less noisy and more stable in operation. Clearly a pure sine wave would be needed. Does anyone have any experience of using one of these? Would it produce a clean supply much the same as that produced by a PS audio power plant, but from a battery instead of the mains?
Inverters are much cheaper than Power plants, a pure sine wave 150W is approx £150-200.
Regards
Mark
Mark,
You may run into other problems. For example, the output impedance of the inverter may be higher than expected, meaning that the output voltage could droop under load. The output may contain bothersome noise from the switching tecnhique used to generate the sinewave. The output frequency may not be that stable or precisely 50Hz (which may or may not be a problem).
In other words it may not be as clean and perfect a mains supply as hoped.
In addition, I think that you will need more than 150W. (The VA rating will need to be higher than expected because the load will have reactive components.)
The battery requirement is something to think about. Consider, you are playing music loud. With pre-amp, CD player as well as power amp, peak consumption could be let's say 200W, battery (12V) current about 20 Amps. You can work out how long a typical car battery would last and how long would be needed to charge up.
Finally a car battery is not intended for deep discharge, it could have a shorter than expected lifetime and the capacity would be lass than expected.
Unless you want to be able to play music during a power cut, probably not such a good idea.
Quite aside from that DC to AC and back to DC.
I suppose you could always put enough batteries together and power the kit straight from that.
But then you could run into internal impedance problems and ...
BTW - The price you quoted is quite good. At home I have a 1800 W sinewave inverter which is under constant solar trickle charge and is used to keep the home automation installation running in the event of power failures. (It's hard to get in without power.) I think that cost about 1,600 GBP.
If you do decide to use an inverter I'd be interested to know how it works.
Regards,
Paul.
You may run into other problems. For example, the output impedance of the inverter may be higher than expected, meaning that the output voltage could droop under load. The output may contain bothersome noise from the switching tecnhique used to generate the sinewave. The output frequency may not be that stable or precisely 50Hz (which may or may not be a problem).
In other words it may not be as clean and perfect a mains supply as hoped.
In addition, I think that you will need more than 150W. (The VA rating will need to be higher than expected because the load will have reactive components.)
The battery requirement is something to think about. Consider, you are playing music loud. With pre-amp, CD player as well as power amp, peak consumption could be let's say 200W, battery (12V) current about 20 Amps. You can work out how long a typical car battery would last and how long would be needed to charge up.
Finally a car battery is not intended for deep discharge, it could have a shorter than expected lifetime and the capacity would be lass than expected.
Unless you want to be able to play music during a power cut, probably not such a good idea.
Quite aside from that DC to AC and back to DC.
I suppose you could always put enough batteries together and power the kit straight from that.
But then you could run into internal impedance problems and ...
BTW - The price you quoted is quite good. At home I have a 1800 W sinewave inverter which is under constant solar trickle charge and is used to keep the home automation installation running in the event of power failures. (It's hard to get in without power.) I think that cost about 1,600 GBP.
If you do decide to use an inverter I'd be interested to know how it works.
Regards,
Paul.