I would shop around for a convection cooled version, cause this is audio and there's that noisy fan running full bore. unregulated linear is more power efficient, no current limiting stops, and no worry about switching noise beating w/ the internal SMPS creating in-band stuff.
me I'd go green with solar cells and a storage battery, get a schematic to adjust the internal SMPS set points.
me I'd go green with solar cells and a storage battery, get a schematic to adjust the internal SMPS set points.
older off-line SMPS without power factor correction (PFC ) is essentially a voltage doubler ie mains connected diodes tied directly to bulk caps. Some use a series thermistor for softer start, but that spoils better efficiencies. So when SMPS is turned on, the 1st few AC cycles have to charge up a flat cap voltage. This looks almost like a dead short w/o any XFMR resistance.
I don't know the correct name, so I'll refer to this particular style as "direct on line SMPS".
This connects a rectifier across the mains and charges a high ripple capacity capacitor to ~340Vdc from 240Vac.
That 340V trying to start charging a discharged low ESR, low ESL capacitor is what inherently requires a soft start to prevent all the fuses back to the grid from opening.
A SMPS needs a soft start, more than any transformer isolated supply.
This connects a rectifier across the mains and charges a high ripple capacity capacitor to ~340Vdc from 240Vac.
That 340V trying to start charging a discharged low ESR, low ESL capacitor is what inherently requires a soft start to prevent all the fuses back to the grid from opening.
A SMPS needs a soft start, more than any transformer isolated supply.
RE we in the USA call em "off-line SMPS" a misnomer really. hopefully more and more of them will be "green" ie PFC designs to help mains power factor and sine wave distortion issues. I doubt HF noise will get any better tho.
That never happens for less than 1KW due to time constants of breakers being really slow, thankfully. This is a transient condition that lasts only for a few cycles of AC. But most all > 300W use a thermistor bypassed with a Triac.
That never happens for less than 1KW due to time constants of breakers being really slow, thankfully. This is a transient condition that lasts only for a few cycles of AC. But most all > 300W use a thermistor bypassed with a Triac.
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I believe that's what is , i haven't seen a series thermistor in a 500W PSU for some time now ... Probably because the year we are already in .
Yeah , breakers will trip only after a few milliseconds .
nice
Just a quick question, if I use bridged rectifier, will it be safe to consider a definite loss of 1.4V after rectification? The reason is I wanted to build an exact same thing but unable to find a decent 500VA or more at 10 or 11 Volts, but was able to find a 600VA at 12Vac. I know this would result in about 15.5VDC.
My main objective is to build a 12-15VDC unregulated linear supply using toroidal transformer at about 90A. Is this crazy?
thanks.
Just a quick question, if I use bridged rectifier, will it be safe to consider a definite loss of 1.4V after rectification? The reason is I wanted to build an exact same thing but unable to find a decent 500VA or more at 10 or 11 Volts, but was able to find a 600VA at 12Vac. I know this would result in about 15.5VDC.
My main objective is to build a 12-15VDC unregulated linear supply using toroidal transformer at about 90A. Is this crazy?
thanks.
What are you looking for ? higher power counterparts should have more voltages available not lower ...
Maybe this is waste of time, but the reason is that I am planning to install two IB 18" subwoofers in my home theater, which I already spent hefty sum of money into two single ohm capable car amplifiers. I don't have too many options powering these amp. The IB Subwoofer I'm planning to acquire as soon as they have in stock is a dual 2-Ohm DVC, able to dissipate about 1,000Watt RMS. The amplifier takes three 30A fuses, which should be accurately able to provide about 1080Watt RMS. The only way to power these two amps is to build a high current supply, capable of providing about 90A or more at 12-14Volts.
Hi tsaelee
yes you can use full bridges for an extra diode drop. If you can get a single toroid with 2 x12 V ac windings use 2 x 35A bridges and combine by paralleling them at the +/- outputs. This will have double the losses and heat sinking. note the voltage calculated is simplistic it will be lower at full power. there is ripple voltage, esr losses and wiring losses.
I am very sceptical of car amp watts until I see the schematic I would shoot for 13.5V @ 50A, start doing the math for your 90A cabling!
yes you can use full bridges for an extra diode drop. If you can get a single toroid with 2 x12 V ac windings use 2 x 35A bridges and combine by paralleling them at the +/- outputs. This will have double the losses and heat sinking. note the voltage calculated is simplistic it will be lower at full power. there is ripple voltage, esr losses and wiring losses.
I am very sceptical of car amp watts until I see the schematic I would shoot for 13.5V @ 50A, start doing the math for your 90A cabling!
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implies 4 voice coil each of 2ohm impedance.
You have choices.
Power each 2ohm VC from it's own dedicated 2ohm capable Power amplifier.
Power a series connected pair of voice coils with a 4ohm capable amplifier.
Power a parallel connected pair of voice coils with a 1ohm capable amplifier.
I, using my limited experience, offer the same guarantee that Destroyer often cites and tell you that the worst performing combination will be parallel connected Voice Coils.
1 might as well do series if that's the case .
I have never heard a paralled wired DVC sound good .
Thank you. I am, too, skeptical about the true capability of the amp. As of now, both amps are powered by multiple computer PSUs, parallel connected (I know, dangerous!). The fact that they work quite well with computer supply, I tend to agree with you that they are no more capable of drawing more than 50A, continuous. I play music with heavy bass all the time and no problem so far.
As for the 90A, cabling would be scary! I might have to abandon the whole idea of doing unregulated linear supply.
thanks for your input.
Thanks for the input. Can the drive be powered by just one of the voice coil or both have to be powered? My understanding is that both have be powered, which then limits supposed flexibility to just powering separately or serial connect.
Thanks - I have to take your guy's input into consideration.
I suppose you can do 1 voice coil . But i heard series gives much nicer output , not sure about that , i heard it in a Celestion thread .
Got any old microwave ovens around? Find one on the side of the road,and rip out it's transformer,cut/punch the HV secondary winding off (it's not too hard) and rewind your own with ~10-15turns of heavy wire.
I used 2x secondaries,each wound with 10AWG wire,into it's own bridge rectifier,then the outputs of the bridge rectifiers are paralleled,and fed into a large chunk of smoothing capacitance. (~105,000uf at the moment.)
Cheapest and easiest way I could think of to get ~13.8V at 50A+ for testing/powering my amps indoors.
I used 2x secondaries,each wound with 10AWG wire,into it's own bridge rectifier,then the outputs of the bridge rectifiers are paralleled,and fed into a large chunk of smoothing capacitance. (~105,000uf at the moment.)
Cheapest and easiest way I could think of to get ~13.8V at 50A+ for testing/powering my amps indoors.
Well , i might as well wait for my microwave to be thrown away .
But its no matter , because i decided to go SMPS .
I read the first page or two and did a jump to the end, so forgive me if this has been covered already.
A car does not run on 12V, first of all.
On a fully charged lead acid battery, each cell is 2.2V, so a "12 volt" lead acid battery is 13.2V in a charged state. It can actually be higher if measured with a very low load, like a Volt-Ohm-Amp meter. That's one reason why garages use a "load tester" which is not the same as a VOM (another reason is the actual condition of the battery, ie it's ability to maintain a charge or in essence it's remaining life, is not tested properly without a load applied).
The alternator has to be able to generate higher than that, under load, to charge the battery. It's regulated, but not tightly since motor speed plays a role in it's available output.
[As an aside, there are different regulator designs, but one common one is the alternator does not output a charge voltage until it is "flashed" by revving the engine up to about 1800 RPM or so at least once. It can idle down below that once flashed and it will still charge. A point to keep in mind if you are trying to charge a low battery or if you do cold-weather starts and let the engine + vehicle heating system warm up before driving.
If you run one of these alternator/regulator designs (AFAIK, that's any GM or Honda, check online for your car at alternator forums if it's another make) Blip the throttle to 2000-something once it's started before you go drink your coffee and let everything come up to temp, or it's all battery you're running on, which is not advisable in a short trip since about a half hour of charging is needed to regain full battery state. It's not particularly fuel efficient or environmentally friendly, and is a significant contributor to engine wear to idle excessively a cold (as in under 190F/ 90C) engine, but in the real world that stuff goes out the window at 40 below zero.]
Generally it's considered "charging" if it can do around fourteen and a half volts, more or less.
[Another aside ... Modern cars (anything made less than 50 years ago) often don't have direct reading voltage gauges, ... they are voltage gauges but no real usable numbers on the gauge itself ... and if you've got idiot lights, you have no idea beyond "supposed to be working" (light off) and "might be broken" (light on or off).
An aftermarket gauge, eg Autometer brand or equivalent, with real usable numbers, is a handy addition to a car with a serious stereo and idiot lights, or a nebulous "charge - normal - discharge" marked factory gauge, if you can live with the appearance of the installation. You can buy Ammeters, but don't ... they draw current for no real useful purpose when the voltage gauge is more useful and doesn't draw much at all.]
Now, back to the topic of running car gear in the home ...
I've seen 16V on alternator output in a vehicle with a voltage-reading (aftermarket) gauge.
Under straight battery power (engine off) it should run for a number of hours under steady discharge. So, 11V or perhaps less .... in some cases as little as 9V, which is around the danger zone for a battery ... discharge lower and it may not recover.
Finally, an alternator whose regulator has malfunctioned may charge above 16V. This will kill the battery in short order, so many devices are going to shut down above 16-something volts.
With a low current draw device, it might work down to 9V, with a high current device (like a car amp) it probably will shut down sooner, to preserve the battery condition; maybe 11V.
14.4V is the "ideal" charging voltage under load, but with low load the vehicle's charging voltage might be higher, and with high loads it could easily be lower, especially if the amperage draw is at the limit of the alternator's output in Amps ... it needs headroom to handle multiple current draws (headlights are a huge one, but heater/AC motors are also heavy demand. Run both, plus an amp, and the alternator should be capable of keeping the voltage with the engine running at 14.4V, so under low load it might be above that).
Summing up, an amp designed for conventional car/truck use should almost always be able to run in the range of 11~16V without damage but not necessarily at optimum. Throw in a bit of headroom on both sides and the practical limit might be a half a volt higher or lower, maybe even a volt, but you can't count on that for sure.
A car does not run on 12V, first of all.
On a fully charged lead acid battery, each cell is 2.2V, so a "12 volt" lead acid battery is 13.2V in a charged state. It can actually be higher if measured with a very low load, like a Volt-Ohm-Amp meter. That's one reason why garages use a "load tester" which is not the same as a VOM (another reason is the actual condition of the battery, ie it's ability to maintain a charge or in essence it's remaining life, is not tested properly without a load applied).
The alternator has to be able to generate higher than that, under load, to charge the battery. It's regulated, but not tightly since motor speed plays a role in it's available output.
[As an aside, there are different regulator designs, but one common one is the alternator does not output a charge voltage until it is "flashed" by revving the engine up to about 1800 RPM or so at least once. It can idle down below that once flashed and it will still charge. A point to keep in mind if you are trying to charge a low battery or if you do cold-weather starts and let the engine + vehicle heating system warm up before driving.
If you run one of these alternator/regulator designs (AFAIK, that's any GM or Honda, check online for your car at alternator forums if it's another make) Blip the throttle to 2000-something once it's started before you go drink your coffee and let everything come up to temp, or it's all battery you're running on, which is not advisable in a short trip since about a half hour of charging is needed to regain full battery state. It's not particularly fuel efficient or environmentally friendly, and is a significant contributor to engine wear to idle excessively a cold (as in under 190F/ 90C) engine, but in the real world that stuff goes out the window at 40 below zero.]
Generally it's considered "charging" if it can do around fourteen and a half volts, more or less.
[Another aside ... Modern cars (anything made less than 50 years ago) often don't have direct reading voltage gauges, ... they are voltage gauges but no real usable numbers on the gauge itself ... and if you've got idiot lights, you have no idea beyond "supposed to be working" (light off) and "might be broken" (light on or off).
An aftermarket gauge, eg Autometer brand or equivalent, with real usable numbers, is a handy addition to a car with a serious stereo and idiot lights, or a nebulous "charge - normal - discharge" marked factory gauge, if you can live with the appearance of the installation. You can buy Ammeters, but don't ... they draw current for no real useful purpose when the voltage gauge is more useful and doesn't draw much at all.]
Now, back to the topic of running car gear in the home ...
I've seen 16V on alternator output in a vehicle with a voltage-reading (aftermarket) gauge.
Under straight battery power (engine off) it should run for a number of hours under steady discharge. So, 11V or perhaps less .... in some cases as little as 9V, which is around the danger zone for a battery ... discharge lower and it may not recover.
Finally, an alternator whose regulator has malfunctioned may charge above 16V. This will kill the battery in short order, so many devices are going to shut down above 16-something volts.
With a low current draw device, it might work down to 9V, with a high current device (like a car amp) it probably will shut down sooner, to preserve the battery condition; maybe 11V.
14.4V is the "ideal" charging voltage under load, but with low load the vehicle's charging voltage might be higher, and with high loads it could easily be lower, especially if the amperage draw is at the limit of the alternator's output in Amps ... it needs headroom to handle multiple current draws (headlights are a huge one, but heater/AC motors are also heavy demand. Run both, plus an amp, and the alternator should be capable of keeping the voltage with the engine running at 14.4V, so under low load it might be above that).
Summing up, an amp designed for conventional car/truck use should almost always be able to run in the range of 11~16V without damage but not necessarily at optimum. Throw in a bit of headroom on both sides and the practical limit might be a half a volt higher or lower, maybe even a volt, but you can't count on that for sure.
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Car Alternators are muchly variable that is , put short .
so i'm led to believe my Alpine MRV-F400 is very much 12-16 , as it's power draw is quite insane , but that's looking at the fuse .
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