unconventional layout running the whole signal through the trimmer pot. Yes that works.
I would tap in the input and output at the 6k2 resistor. That way yhe major part of the current takes the shortest route through and passes that current through the higher quality fixed resistor. Only a tiny portion of the current passes through the trimmer.
I would tap in the input and output at the 6k2 resistor. That way yhe major part of the current takes the shortest route through and passes that current through the higher quality fixed resistor. Only a tiny portion of the current passes through the trimmer.
A 9 V power supply
I want to improve and build a new power supply to my Squeezebox Duet. The need is 9 volts. The need for current is unknown, but I expect that we do not talk about A, but mA.
I have not taken the time to read this long thread, but I have noticed that a suggestion to print was published relatively early in the thread by Salas.
To avoid having to "hunt me up" a post that describes a solution to my needs, I ask for help to a BOM list of what components I should use to get the 9 V DC. The transformer I want to use is a 24VA with 2x12 V AC (connected in parallel).
Eivind Stillingen
I want to improve and build a new power supply to my Squeezebox Duet. The need is 9 volts. The need for current is unknown, but I expect that we do not talk about A, but mA.
I have not taken the time to read this long thread, but I have noticed that a suggestion to print was published relatively early in the thread by Salas.
To avoid having to "hunt me up" a post that describes a solution to my needs, I ask for help to a BOM list of what components I should use to get the 9 V DC. The transformer I want to use is a 24VA with 2x12 V AC (connected in parallel).
Eivind Stillingen
If...
Measure the current draw of the Duet using your multimeter with its stock power supply, you really want to know the real world current requirements to tune the Salas reg for ideal performance. A 12 VAC tranny should be fine for 9 VDC output.
Measure the current draw of the Duet using your multimeter with its stock power supply, you really want to know the real world current requirements to tune the Salas reg for ideal performance. A 12 VAC tranny should be fine for 9 VDC output.
Power to the Sqeezbox Duet
Salas/ Barrows
Thanks for your reply. I could of course have followed the advice and measured power consumption from the existing power supply.
But Welborne Labs supplies a power supply designed for Sqeezbox Duet. Here is what they write about the need for power to the Duet:
What is the amperage rating of the supply? Our power supply can provide up to 3.5 amperes of current. I believe the Squeezebox 3 and Duet require 1 amp, earlier versions may have been spec'd 1.5 amps so our upgrade has plenty of headroom
As previously mentioned, I have a transformer of 24 VA and 2x12 V AC that I want to use. Theoreticaly I should be able to extract
2 A from the transformer, but I choose to go for 1.5 A. This will be a lot less than what the Welborne power supply (3,5 A) can give, but 1,5 A is good within what Welborne describes as what Sqeezbox needs.
Eivind Stillingen
Salas/ Barrows
Thanks for your reply. I could of course have followed the advice and measured power consumption from the existing power supply.
But Welborne Labs supplies a power supply designed for Sqeezbox Duet. Here is what they write about the need for power to the Duet:
What is the amperage rating of the supply? Our power supply can provide up to 3.5 amperes of current. I believe the Squeezebox 3 and Duet require 1 amp, earlier versions may have been spec'd 1.5 amps so our upgrade has plenty of headroom
As previously mentioned, I have a transformer of 24 VA and 2x12 V AC that I want to use. Theoreticaly I should be able to extract
2 A from the transformer, but I choose to go for 1.5 A. This will be a lot less than what the Welborne power supply (3,5 A) can give, but 1,5 A is good within what Welborne describes as what Sqeezbox needs.
Eivind Stillingen
Interesting you're promoting the Reflector now. Is that now officially the latest and greatest? I thought rcruz was the only one who actually had built it...
I will be integrating some regs into my dac this week. So far i have used v1 on external boards but i am planning to integrate the regs now on the dac board. Best to switch to Reflektor now?
I will be integrating some regs into my dac this week. So far i have used v1 on external boards but i am planning to integrate the regs now on the dac board. Best to switch to Reflektor now?
The currents quoted (1A and 1.5A) are almost certainly peak current. These will be complicated and time consuming to measure/confirm.
Most amplifiers draw a continuous quiescent current (Iq) when the load is drawing zero current. When the load draws output current, this appears as extra current from either supply rail alternately (some -ve and some +ve) to give the AC output music signal.
If the duet meets this typical current demand then you cannot use a CCS Shunt Regulator unless you are prepared to set the CCS to some current greater than the maximum peak transient demand of the duet. this would be >=1.6Adc
A 24VA, 12+12Vac transformer can supply a continuous maximum AC current of 1Aac to a pair of 12r0 resistors.
When converted to DC using a capacitor input filter, the maximum continuous current is limited to ~500mAdc.
To allow the transformer to run cool, the average current should not exceed ~50% of the max DC current, i.e. <=~250mAdc.
This is well above the normal amplifier demands of a low bias ClassAB amplifier which may draw anywhere from 10mA to 100mA of quiescent current.
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Its full of digital chips drawing like a small computer. FYI:
http://reviews.cnet.com/digital-aud...ech-squeezebox-duet/4505-6470_7-32815168.html
http://reviews.cnet.com/digital-aud...ech-squeezebox-duet/4505-6470_7-32815168.html
Thanks for the new input to a regulated power supply to my Squeezebox Duet.
I have two good reasons to choose an alternative that has been evaluated in this thread earlier:
1. It is proposed to print (veroboard is not my "cup of tea")
2. I already have semiconductors and other components to this version.
I think here on the version referred to in # 226
Squeezebox is, as you describe Andrew, in no need for a continuous flow of 1.5 A. The transformer I refer to (24VA 2x12 V AC, connected in parallel, will not be able to deliver 1.5 A continuous)
I think that my needs will be well covered if someone can give me a BOM list to the version described in # 226 with the following would cover:
1. Transformer 12 V AC
2. Voltage out 9V DC
3. Current 1.5 A peak.
Eivind Stillingen
I have two good reasons to choose an alternative that has been evaluated in this thread earlier:
1. It is proposed to print (veroboard is not my "cup of tea")
2. I already have semiconductors and other components to this version.
I think here on the version referred to in # 226
Squeezebox is, as you describe Andrew, in no need for a continuous flow of 1.5 A. The transformer I refer to (24VA 2x12 V AC, connected in parallel, will not be able to deliver 1.5 A continuous)
I think that my needs will be well covered if someone can give me a BOM list to the version described in # 226 with the following would cover:
1. Transformer 12 V AC
2. Voltage out 9V DC
3. Current 1.5 A peak.
Eivind Stillingen
The Squeezebox Receiver (from the Duet) should not draw more than 560 mA (it's written below the box and on the wall wart 
) I don;t want to open the box to confirm that, but I've measured the power draw at the mains side and it never exceeded 4 Watts in Wifi Mode. It's fairly constant in use, but with the LAN plugged in, it went up to 5 Watts at startup for a short time, so the 9V / 560mA max is confirmed.
I suppose setting the Reg to 600mA for the Duet should be enough (maybe even slightly less if you're concerned about heat since the 560mA is only temporary).
) I don;t want to open the box to confirm that, but I've measured the power draw at the mains side and it never exceeded 4 Watts in Wifi Mode. It's fairly constant in use, but with the LAN plugged in, it went up to 5 Watts at startup for a short time, so the 9V / 560mA max is confirmed.I suppose setting the Reg to 600mA for the Duet should be enough (maybe even slightly less if you're concerned about heat since the 560mA is only temporary).
New powerunit to Squeezebox Duet
With the comments from Lazybutt, it appears that the most important parameters are in place to give Sqeezebox a new and better power than the one provided. Although I have not got the idea to study what was written on the back of the accompanying wall wort
Thank you Salas you for taking the time to create a BOM list.
Eivind Stillingen
With the comments from Lazybutt, it appears that the most important parameters are in place to give Sqeezebox a new and better power than the one provided. Although I have not got the idea to study what was written on the back of the accompanying wall wort
Thank you Salas you for taking the time to create a BOM list.
Eivind Stillingen
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