i was just wondering what everyone here thought about battery power supplies? you can buy some nice gel cell (lead acid ) batteries surplus for around $20. get a couple of them together, and you could easily power a cd player or a pre-amp for hours. and when its off, a relay switches on and starts charging...
for an amp it wouldnt be TOO wise, because power drain is too much. but from what i understand, a good battery bank could yield around 10 hours of playback before recharging. even if you had a slow trickle charger, after watching a 3 hour movie or something, it would take 6 hours to charge. BUT, you would techinically be still left with 7 hours anyway... 10 hours is a LONG time to listen to a stereo continuious. you would at least take a few hour break!
this would eliminate quite of a bit of the cost of making a higher end power supply section for a cd player or preamp, would it not? a simple battery pack could be a perfect power source, and be relatively easy and cheap to build, not to mention would rival many extreme power supply designs.
let me know what you all think!
for an amp it wouldnt be TOO wise, because power drain is too much. but from what i understand, a good battery bank could yield around 10 hours of playback before recharging. even if you had a slow trickle charger, after watching a 3 hour movie or something, it would take 6 hours to charge. BUT, you would techinically be still left with 7 hours anyway... 10 hours is a LONG time to listen to a stereo continuious. you would at least take a few hour break!
this would eliminate quite of a bit of the cost of making a higher end power supply section for a cd player or preamp, would it not? a simple battery pack could be a perfect power source, and be relatively easy and cheap to build, not to mention would rival many extreme power supply designs.
let me know what you all think!
I powered an amp off some 17AH 12V lead acids out of a UPS while I was waiting on the transformers to come. It was a SOZ so it was more like listen for an hour charge overnight. I just took the batteries to the garage and charged them with a car battery charger. It worked well. You wouldn't need much in the way of caps. For a preamp you could run for days at a time if not weeks.
Darrell Harmon
Darrell Harmon
I think with the cd it would be best just to beef up caps on the analog section. The digital can be left alone. I open up my cd (Onkyo DXC-370) and was impressed with most of the insides. The output actually was class A with some TO-220 parts on heatsinks.
I was thinking of finding the output of the dac and building a new preamp, but I decided not to because it was good already.
Darrell Harmon
I was thinking of finding the output of the dac and building a new preamp, but I decided not to because it was good already.Darrell Harmon
well, its an NAD, its already got all panasonic caps in there. it could use black gates, but thats another step.
im trying to make this as high end as i can. clock will be replaced, new PS, beefed up analog section, dampening, etc.
ill give it a though on the battery supply. allelectronics has some cheap lead acids for like $6. one or two would be fine for a couple hours of playback. could be a cheap alternative.
im trying to make this as high end as i can. clock will be replaced, new PS, beefed up analog section, dampening, etc.
ill give it a though on the battery supply. allelectronics has some cheap lead acids for like $6. one or two would be fine for a couple hours of playback. could be a cheap alternative.
im actually planning on it. its a decent cd player to begin with. i wanted to start with a solid player from scratch, upgrade the mechanics (casing, transport, etc...), then electronically.
an external DAC will eventually come. thats why im pondering the battery supply. that too could power the DAC...
an external DAC will eventually come. thats why im pondering the battery supply. that too could power the DAC...
My last DAC project used battery supplies. I used 5x 1.2AH Sealed Lead Acid batteries to produce dual +/-12V supplies to power the DAC's and the output Op-amps and a single supply for the rest of the digital circuitry. The Op-amps were connected directly to the batteries, but the DAC's had regulators to reduce it to +/-5V.
A few points:
I set the charging arrangement up so when I turned the DAC off, it really just turned on the charger, and the circuitry worked continiously. All fine except when you unplug it from the mains for a long time. I would have to open the DAC up and disconnect all 5 batteries, otherwise they would go dead flat. Not good for the life of the battery.
You will need some supply capacitance near the circuitry, as you need to lower the PS impedance at higher frequencies. All they have to do is supply power at higher frequencies, not to filter out ripple.
When rating the batteries, to improve their service life, make sure you never get them close to being discharged. A fully charged battery is 13.6V, and can be considered fully discharged at around 11.5V Don't let them go below 12V if you can help it.
Experiement and enjoy, it is a very viable option to improve performance, especially in lower powered equipment
Cheers, Adrian
A few points:
I set the charging arrangement up so when I turned the DAC off, it really just turned on the charger, and the circuitry worked continiously. All fine except when you unplug it from the mains for a long time. I would have to open the DAC up and disconnect all 5 batteries, otherwise they would go dead flat. Not good for the life of the battery.
You will need some supply capacitance near the circuitry, as you need to lower the PS impedance at higher frequencies. All they have to do is supply power at higher frequencies, not to filter out ripple.
When rating the batteries, to improve their service life, make sure you never get them close to being discharged. A fully charged battery is 13.6V, and can be considered fully discharged at around 11.5V Don't let them go below 12V if you can help it.
Experiement and enjoy, it is a very viable option to improve performance, especially in lower powered equipment
Cheers, Adrian
sounds perfect.
i was going to do a few things...
have a trickle charger on them, so when the source is turned off (or just when the cd player or whatever is turned off), the charger initiates. basically, when off, the batteries would be completely disconnected from the player. and, when at full power, they would be disconnected from charger and player.
dual VU meters would be on the front panel, measuring both amperage and volts. this would ensure proper battery life. i would probably just overkill the batteries, so i could listen for hours without a problem.
hum, i think the cd player needs a bigger case
i was going to do a few things...
have a trickle charger on them, so when the source is turned off (or just when the cd player or whatever is turned off), the charger initiates. basically, when off, the batteries would be completely disconnected from the player. and, when at full power, they would be disconnected from charger and player.
dual VU meters would be on the front panel, measuring both amperage and volts. this would ensure proper battery life. i would probably just overkill the batteries, so i could listen for hours without a problem.
hum, i think the cd player needs a bigger case
well, as an update, almost all the work is done for the battery supply for my NAD cd player. i have finished all but the relay network and the wiring needed to switch the setup from a 12v over to a 36v.
here are the details:
there are 3 12v 5AH sealed lead acid batteries hooked up in parallel when charging. the charger is actually a velleman kit (the intelligent lead acid charger). it works very well, and is very efficient. its powered by a 40VA xformer. however, when the player is kicked on, the charger disengages, and the batteries are then kicked over to be hooked up in series, thus providing 36v.
it will be kinda slick once im finally done with it. just need to get the relays and wire them to the batteries, everything else is done and tested. the things took a whole 18 hours to charge from start to finish. 15AH total between them. should be MORE than enough for the cd player. (i use my equipment a lot...)
ill post pics once i get the relays setup (hopefully tomorrow).
as per the advice of kiwi_abroad, i am going to add master kill switches to the back of the box. when those are off, the batteries will be completely disconnected from the system, just in case you ever needed to unplug it for awhile.
oh, and im still curious what value of caps i need to lower the impedance at higher frequencies. im not an EE, and quite frankly i SUCK at electronics, so i really dont know what i need to do here. help maybe?
here are the details:
there are 3 12v 5AH sealed lead acid batteries hooked up in parallel when charging. the charger is actually a velleman kit (the intelligent lead acid charger). it works very well, and is very efficient. its powered by a 40VA xformer. however, when the player is kicked on, the charger disengages, and the batteries are then kicked over to be hooked up in series, thus providing 36v.
it will be kinda slick once im finally done with it. just need to get the relays and wire them to the batteries, everything else is done and tested. the things took a whole 18 hours to charge from start to finish. 15AH total between them. should be MORE than enough for the cd player. (i use my equipment a lot...)
ill post pics once i get the relays setup (hopefully tomorrow).
as per the advice of kiwi_abroad, i am going to add master kill switches to the back of the box. when those are off, the batteries will be completely disconnected from the system, just in case you ever needed to unplug it for awhile.
oh, and im still curious what value of caps i need to lower the impedance at higher frequencies. im not an EE, and quite frankly i SUCK at electronics, so i really dont know what i need to do here. help maybe?
bypasscaps for battery PSU.
The complete circuit can be found at http://thunderstoneaudio.nav.to/
Hope this helps
The complete circuit can be found at http://thunderstoneaudio.nav.to/
Hope this helps
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