Hi,
I have a stupid question. I saw the R1 best setting for Dam1021 is around 2.0 Ohm in the positive rail, it can provide 300mA including spare current. Now I want to supply Amanero USB board by same source. I will put TPS7A4701 regulator for 5V between them.
I checked user manual that amanero consume 605mW when it powered by 5V USB bus. What if I give 10V from Salas UltraBiB, dose it consume 60.5mA?
Then I have to add 60.5mA in 300mA, total 360.5mA. For R1 is around 1.65Ohm. Am I right?
Thanks.
I have a stupid question. I saw the R1 best setting for Dam1021 is around 2.0 Ohm in the positive rail, it can provide 300mA including spare current. Now I want to supply Amanero USB board by same source. I will put TPS7A4701 regulator for 5V between them.
I checked user manual that amanero consume 605mW when it powered by 5V USB bus. What if I give 10V from Salas UltraBiB, dose it consume 60.5mA?
Then I have to add 60.5mA in 300mA, total 360.5mA. For R1 is around 1.65Ohm. Am I right?
Thanks.
Thank you for explanation Salas! I just added some radiators for it => very cool now.
Another question: I read in this thread somewhere that cable must be very thick in output of UltraBib. But is it possible to use cable 1 meter and 20AWG?
It is possible, it will not oscillate, but it adds resistance and inductance that compromises the performance to an extent. The thickest shortest possible cables and nearest possible distance to the load pays out in subjective sense of more clarity and authority. Its a low output impedance regulator type and you want to preserve that. Depends on the type of the load also. Analog, digital, how many mA it pulls peak to average, its PSRR. Some will be more indifferent to output impedance than others.
Ok. So minimum impedance of UltraBib is 50-150 uOhm. 18 AWG, for example, 1 meter will add 39 uOhm. Not really extremely much. Capacitance also must not be much if wire core in teflon tube.
Am I right?
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Increase C2 to 1000uF for best voltage ref VLF noise filtering. On clocks especially it helps with phase noise. Digital is more sensitive to VLF rail noise. Your cable Zout alright-ish for digital. Make it tight twisted pair so it does not rise its Zout further in HF.
Thank you for advises!
For wire I used this one:
7N copper pure Silver Nordost Valhalla DIY Top rated shield Speaker Audio Signal Cable 1mm Headphone Cable Vinshle Hifi amp| | - AliExpress
It is excellent for sound, same for power: mono core wire with good copper, silver plated. Plus, of couse, twisted it.
already did it, as you said to me before.
For wire I used this one:
7N copper pure Silver Nordost Valhalla DIY Top rated shield Speaker Audio Signal Cable 1mm Headphone Cable Vinshle Hifi amp| | - AliExpress
It is excellent for sound, same for power: mono core wire with good copper, silver plated. Plus, of couse, twisted it.
Hello Salas,
I am trying to build ultrabib for +/-5V and having strange issue with -5V. +5V is fine and working as expected.
I was able to dial in -5V (input is 9V ac) and both LED's are glowing fine. I was thinking everything is fine. But after some time, I noticed the attached heatsink quite warm on the -5V side whereas the +5V was not warm.
I checked the voltage across R1 (value of 2.2ohms, 3W) and it showed around 1.9V which translates to around 860mA current. The same voltage drop is around 0.57V on the positive regulator which translates to around 260mA which is what is expected. So, there is a huge current draw on the negative regulator which is causing the heatsink to get warm and is not expected.
To debug, I have done the following.
1. Reflowed all the solder and still see the same issue.
2. I measured all the resistances and noticed one anomaly. R4 resistor is measuring 80ohms instead of 270 ohms. This is measuring correct value (270 ohms) in the working positive regulator. To check further, I removed the J1 transistor and then the resistor was measuring 270 ohms. I replaced J1 with an extra I had and it then again measures 80 ohms. So not sure why it is not reading the correct value of resistor.
Let me know what else to measure to debug this issue.
Thanks
Balaji
I am trying to build ultrabib for +/-5V and having strange issue with -5V. +5V is fine and working as expected.
I was able to dial in -5V (input is 9V ac) and both LED's are glowing fine. I was thinking everything is fine. But after some time, I noticed the attached heatsink quite warm on the -5V side whereas the +5V was not warm.
I checked the voltage across R1 (value of 2.2ohms, 3W) and it showed around 1.9V which translates to around 860mA current. The same voltage drop is around 0.57V on the positive regulator which translates to around 260mA which is what is expected. So, there is a huge current draw on the negative regulator which is causing the heatsink to get warm and is not expected.
To debug, I have done the following.
1. Reflowed all the solder and still see the same issue.
2. I measured all the resistances and noticed one anomaly. R4 resistor is measuring 80ohms instead of 270 ohms. This is measuring correct value (270 ohms) in the working positive regulator. To check further, I removed the J1 transistor and then the resistor was measuring 270 ohms. I replaced J1 with an extra I had and it then again measures 80 ohms. So not sure why it is not reading the correct value of resistor.
Let me know what else to measure to debug this issue.
Thanks
Balaji
Hi,
If this not an original board check the layout against the schematic to make sure R4 sits at J1's source pin with its other leg linked to its gate pin node with Q1's collector and R3. Not to be sitting between J1's source and drain. Either incorrect J1 orientation in placement or incorrect board connections could have created a mistake.
See also if there is an issue about a dead BC337-40 Q1 or simply wrong type Q1 (337 and 327 tiny lettering on TO-92 can trick the eye).
If this not an original board check the layout against the schematic to make sure R4 sits at J1's source pin with its other leg linked to its gate pin node with Q1's collector and R3. Not to be sitting between J1's source and drain. Either incorrect J1 orientation in placement or incorrect board connections could have created a mistake.
See also if there is an issue about a dead BC337-40 Q1 or simply wrong type Q1 (337 and 327 tiny lettering on TO-92 can trick the eye).
external psu
Hi,
I'm currently populating two pcbs for the ba3 preamp.
I plan to place the ubibs and the amplifier in one case and the transformer, diodes, caps etc. in another.
Since the power supply is external, some questions arose.
- what capacity should i use for the caps in front of the ubib? I will use the diodes D1-4 and Transformer is 50 VA 2x 24v.
- is that correct, I connect DC +/- to RF to the respective board and 0 to the ground of c1?
- do I have to pay attention to anything else regarding the external power supply?
Besides, is it better to steal the power for the muses board after the ubib or before? this would then be converted to 15v using 78/79 regulators.
Thanks,
Jules
Hi,
I'm currently populating two pcbs for the ba3 preamp.
I plan to place the ubibs and the amplifier in one case and the transformer, diodes, caps etc. in another.
Since the power supply is external, some questions arose.
- what capacity should i use for the caps in front of the ubib? I will use the diodes D1-4 and Transformer is 50 VA 2x 24v.
- is that correct, I connect DC +/- to RF to the respective board and 0 to the ground of c1?
- do I have to pay attention to anything else regarding the external power supply?
Besides, is it better to steal the power for the muses board after the ubib or before? this would then be converted to 15v using 78/79 regulators.
Thanks,
Jules