Hi jkeny
The DC varies with load unless a servo loop is used to stabilize the generator output voltage. The generator produces ripple voltage (my setup produced approx. 1000 Hz ripple). It's easier to filter 1000Hz ripple instead of 100 or 120 Hz ripple.
Today I followed soundcheck's advice and added a huge capacitance (60,000uF) in parallel with the two lead-acid batteries (6 x Aerovox 10,000uF / 63V in parallel). Sound quality has improved significantly now, even cleaner, and incredible micro detail.
The DC varies with load unless a servo loop is used to stabilize the generator output voltage. The generator produces ripple voltage (my setup produced approx. 1000 Hz ripple). It's easier to filter 1000Hz ripple instead of 100 or 120 Hz ripple.
Today I followed soundcheck's advice and added a huge capacitance (60,000uF) in parallel with the two lead-acid batteries (6 x Aerovox 10,000uF / 63V in parallel). Sound quality has improved significantly now, even cleaner, and incredible micro detail.
Hi Tolu,
This depends on audio set resolution, the better the equipment gets, the easier these differences can be heard.
With the SD-player these differences are clear as day, no doubt about it. The differences between both a mains and a battery power supply can also be measured of course.
The SD-player now has display dimming (to reduce current consumption and to adjust to lighting conditions). Now the display can be set to bright, dim, and off. When switched-off, the display lights briefly after pressing keys, or disk / track change during playing. The display dim mode is set by pressing the stop key when no SD-card is inserted. When selecting "off", current consumption should drop below 200mA. When selecting "dim", current consumption is around 200mA.
One could buy a 12V / 17Ah sealed lead-acid battery for around eur 25 (17 x 18 x 7.7 cm, 6.2 Kg). This would provide approx. 85 hours of continuous operation when display is set at dim. When listening 4 hours a day, the battery would last approx. 3 weeks.
This depends on audio set resolution, the better the equipment gets, the easier these differences can be heard.
With the SD-player these differences are clear as day, no doubt about it. The differences between both a mains and a battery power supply can also be measured of course.
The SD-player now has display dimming (to reduce current consumption and to adjust to lighting conditions). Now the display can be set to bright, dim, and off. When switched-off, the display lights briefly after pressing keys, or disk / track change during playing. The display dim mode is set by pressing the stop key when no SD-card is inserted. When selecting "off", current consumption should drop below 200mA. When selecting "dim", current consumption is around 200mA.
One could buy a 12V / 17Ah sealed lead-acid battery for around eur 25 (17 x 18 x 7.7 cm, 6.2 Kg). This would provide approx. 85 hours of continuous operation when display is set at dim. When listening 4 hours a day, the battery would last approx. 3 weeks.
EC, are you planning on including a SLA charging circuit?
These TI chips may work.
http://focus.ti.com/docs/prod/folders/print/uc3906.html
These TI chips may work.
http://focus.ti.com/docs/prod/folders/print/uc3906.html
maxlorenz said:Dear Soundcheck,
You sound like my wife: she is only happy when I totally agree with her!
Regards,
M
Because - I guess - she usually knows better then you do. Yep. That's the same thing. You are absolutely right. And -- do you ignore her all the time?
In this case your analogy would be perfectly matching to what happened over here for quite some time.
As you remember I am bringing the battery thing up since at least 2 years.
(The same thing with my Linux setup
)And it shows again that communicating in writing at places like this here is not very efficient.
Hi agent.5
There are plenty of readily available, suitable lead-acid battery chargers.
One could use two batteries, one powers the SD-player while the other is being charged and vice versa. This way one always has a charged battery available. One could use a suitable switch to toggle between both batteries and swap the charger connections. The switch prevents a galvanic or capacitive coupling between the battery charger (connected to the mains) and the SD-player.
There are plenty of readily available, suitable lead-acid battery chargers.
One could use two batteries, one powers the SD-player while the other is being charged and vice versa. This way one always has a charged battery available. One could use a suitable switch to toggle between both batteries and swap the charger connections. The switch prevents a galvanic or capacitive coupling between the battery charger (connected to the mains) and the SD-player.
HI guys
How about the charging/switching board from emergency light fixture.
Some of them are using a 12volt battery and solid state switching.
I think it would work well for this project. When main voltage is applied, the battery is charging and there in no 12volt on output, but when it is switched off, 12 volt from battery kicks in.
How about the charging/switching board from emergency light fixture.
Some of them are using a 12volt battery and solid state switching.
I think it would work well for this project. When main voltage is applied, the battery is charging and there in no 12volt on output, but when it is switched off, 12 volt from battery kicks in.
like this one, but maybe with less self checks. You could even use the enclosure it comes in, just remove the heads (those probably don't come attached anyway) and install few switches.
http://www.discountfiresupplies.co....in-Emergency-Spotlight-with-20W-Halogen-Lamps
http://www.discountfiresupplies.co....in-Emergency-Spotlight-with-20W-Halogen-Lamps
Hi dddac,
The SD-player power supply was specifically designed to cope with poor quality external DC power supplies. There is also a set of decoupling caps (total of 3300uF) already mounted on the SD-player mainboard. Therefore the exact location of the 60,000uF capacitors is not very critical.
The 60,000uF is not connected directly in parallel with the batteries in order to lower or equalize battery impedance. There is a 3.3mH choke in series for attenuating battery noise. I also placed a 10nF silvered mica cap across the 60,000uF caps.
The idea is to prevent interference sources from inter-modulating with the audio spectrum.
The SD-player power supply was specifically designed to cope with poor quality external DC power supplies. There is also a set of decoupling caps (total of 3300uF) already mounted on the SD-player mainboard. Therefore the exact location of the 60,000uF capacitors is not very critical.
The 60,000uF is not connected directly in parallel with the batteries in order to lower or equalize battery impedance. There is a 3.3mH choke in series for attenuating battery noise. I also placed a 10nF silvered mica cap across the 60,000uF caps.
The idea is to prevent interference sources from inter-modulating with the audio spectrum.
-ecdesigns- said:
Hi John,
Hope I did not miss this somewhere in the thread but... Will there be modules for just I2S, are the schematics available and is the source code open? I would love to buy or make a module for just the I2S and be able to choose my preferred clock for it (and put it in my 1794/tube DAC).
The thread starts with :
"This thread is about designing a WAV (FLAC) SD-card player for integration in (existing) DACs. It runs on a (divided) DAC master clock, and outputs I2S (64 bit / frame)."
Your product looks really good (don't forget the SD-card-to-iPod adapter for that extra bit of marketshare) but there is no diy (yet)...
Thanks,
Jeroen
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