I just recently read about those alternatives for diode bridges. Very interesting. haha, the bucket list gets longer every day…
that also answers kind of your other point on the USB bridge. Nice on the bucket list, but i will build my latest version with normal PI3 first as it is mostly used right now and widely spread. At some point it might be fun to build another one with just all "known" best tweaks as another reference. Time will tell
As I described in my post, yes any any voltage in between.
The point I made in the post, that "it did not work" had obviously nothing to do with the 5 Volt to the FiFoPi, but all with feeding the Waveio isolator with 5Volt. I had them both from the same supply for the test, so when going back to 3,3 V it worked, but NOT because of 3.3 Volt to the FiFoPi, but as the Waveio isolator was below 5Volt now....
OK, another alternative: what I did yesterday in my bench setup, was feeding both FiFoPi digital side and the Waveio isolator with a 4Volt regulator. The 4 Volt regulator is fed form a small 12 Volt module which supplies 12V to the arduino. So with one power supply I could feed 3 boards
The 4 Volt makes the FiFoPi works fine (as it has a 3.3 Volt regulator on board anyway) and the Waveio has 4 Volt on the isolator, which causes the FiFoPi to NOT have problems at the LVTTL inputs.
again, Waveio with FiFoPi, make sure the Isolator is supplied with anything between 3 and 4.5 Volt
So here is an example how I connected the Waveio with the DDDAC and the FiFoPi….
As said the 4 Volt is NOT critical. I would say, anything between 3.6 and 4.8 Volt will work - hence I went kind of in between …
Alternatively you can feed the Waveio Isolator and FiFoPi digital side with separate supplies of course. Key thing is to keep the Waveio Isolator < 4.8 Volt. FiFoPi will work fine with anything between 3 and 5 volt, but to keep the 3.3V on-board LDO work well, I suggest to keep it > 3.6V
GIF:
As said the 4 Volt is NOT critical. I would say, anything between 3.6 and 4.8 Volt will work - hence I went kind of in between …
Alternatively you can feed the Waveio Isolator and FiFoPi digital side with separate supplies of course. Key thing is to keep the Waveio Isolator < 4.8 Volt. FiFoPi will work fine with anything between 3 and 5 volt, but to keep the 3.3V on-board LDO work well, I suggest to keep it > 3.6V
GIF:
Attachments
Humm it’s now many power supplies and more complex. Rather than the dedicated 4v supply I might use the resistor to drop the voltage like you did to make it work as I suspect that delivers 4v
I did not say it was an extra power supply…. I wrote a 4 Volt regulator (I use a LDO for that) which is fed by an existing 12 Volt power supply (not the one for the DAC, as that one needs to stay at the isolated side of the FiFoPi
oh, edit: … Not sure what voltage you want to drop FROM, but you should not only use a resistor to drop voltage to 4 volt, as that is depending on actual current draw, specially at startup where there is little to no current drawn by the FiFoPi and also as depending on music FS the current varies. Best is to regulate the supply voltage for the FiFoPi and Waveio. If you need a drop resistor to use a LDO, well fine, but you need to take into account maximum current draw…
Last edited:
True but most don’t have another supply other than the 12v and 5v ones in the standard dac. You have extra 12 for the other devices you need to power, correct?
Ah yes true
So must of us have 12v for the main dac and 5v for waveio meaning we will need a third psu to generate the 4v considering isolation needs
Which LDO do you use?
1) well, you ARE adding a device (FiFoPi) and this device has an isolating function. If you power it with the 12 Volt dac supply you defeat the isolation from the FiFoPi and … if you use the 5 Volt power supply from the Waveio you will be putting the WaveIO I2s signals now to refer to the ground, which is the the same as the USB shield, connecting it to your complete domestic Earth.... This is why there is also isolation at the Waveio to start with. So with the FiFoPi you have a third-signal-section which you want isolated from the USB bus AND from the DAC - and here comes your third power supply and the reasons behind
(hence I chose 3 colors in my overview, that was not just for fun or good looks)2) yes and the reason is 1)
3) LDOVR
the good news is, you only need like 100mA.... that can be a small linear supply - I see no direct need for HIGH END stuff at this place (as the re clocker comes after it anyway)
Attachments
Last edited:
1) well, you ARE adding a device (FiFoPi) and this device has an isolating function. If you power it with the 12 Volt dac supply you defeat the isolation from the FiFoPi and … if you use the 5 Volt power supply from the Waveio you will be putting the WaveIO I2s signals now to refer to the ground, which is the the same as the USB shield, connecting it to your complete domestic Earth.... This is why there is also isolation at the Waveio to start with. So with the FiFoPi you have a third-signal-section which you want isolated from the USB bus AND from the DAC - and here comes your third power supply and the reasons behind
2) yes and the reason is 1)
3) LDOVR
the good news is, you only need like 100mA.... that can be a small linear supply - I see no direct need for HIGH END stuff at this place (as the re clocker comes after it anyway)
Yes I get it just want to be sure and sorry for all questions
I have other psu here and another 12v of your design so I am good to make dedicate 4v
It’s best to separate power between BBB and FifoPi isolated side (J5)
You can try to power BBB via J3, but then you will need another psu for FifoPi’s isolated side J5. Take a look at the schematic from Doede on the previous page. This schematic include the WaveIo, but imagine this is your BBB and not WaveIo.
You can try to power BBB via J3, but then you will need another psu for FifoPi’s isolated side J5. Take a look at the schematic from Doede on the previous page. This schematic include the WaveIo, but imagine this is your BBB and not WaveIo.