SMD power supply. Some questions.

[NeilR]

Manuel,

I have previously thought about building a standard Tread into a Serpac H67 to match my Pint/Pimeta that are in H65/H67 cases. Similar problem of space although you are taking it even further.

I came to the conclusion that the best way to bring AC in is just zip cord with a strain relief. There just wasn't room for an IEC or 2 wire inlet jack and something had to give. The next step was to find a fuse holder that would fit. Have you thought about fusing?

An alternative might be to use an AC wart, removing the transformer from the enclosure and freeing up space for more capacitance and whatnot. It isn't as elegant and it gives you a 3rd "thing" to tote around but it would give you room to max out the supply.

What is the battery configuration in your Pint?

 

[JahJahBinks]

A monolithic linear regulator will do the job well. There are over 100 of them on the market today so I am sure you will find one that meets your requirements.

For diodes bridge I recommend HexFred, they are a type of diodes that has better performance than the regular ones.

 

[MASantos]

I haven't thought about fusing. Is it really needed since the current and voltage draws are so low? if yes I might consider placing a 5x20mm fuse.

regarding the IEC I really want to have an input jack and an AC wallwart is definitely out of question.

At the moment the battery configuration in my pint is one 9v battery, but this PS must be able to "deliver" around 110mA.



Quote:

Originally Posted by NeilR Manuel, I have previously thought about building a standard Tread into a Serpac H67 to match my Pint/Pimeta that are in H65/H67 cases. Similar problem of space although you are taking it even further. I came to the conclusion that the best way to bring AC in is just zip cord with a strain relief. There just wasn't room for an IEC or 2 wire inlet jack and something had to give. The next step was to find a fuse holder that would fit. Have you thought about fusing? An alternative might be to use an AC wart, removing the transformer from the enclosure and freeing up space for more capacitance and whatnot. It isn't as elegant and it gives you a 3rd "thing" to tote around but it would give you room to max out the supply. What is the battery configuration in your Pint?

 

[NeilR]

If you get a short somewhere, something is going to act like either a fuse or a small incendiary device, personally I prefer to pick my fusible part

Also consider you are using a metal case. With a 2 wire jack, if one of the primary wires breaks off, you will most likely have a hot case. One of the reasons I thought about using a Serpac H65/H67 is that it is plastic and I thought it would be a little bit safer in that regard.

I think you need about 15V for the Pint charger if you are using 8 cell batts and an LM317 in the Pint. I used a Tread set at 15.6V with an 8 cell 9V, but I had an extra diode between the supply and the Pint's W+ pad to prevent the Pint from draining itself if the supply were attached but turned off (via the supply's LED/RLED). Just throwing this out in case you haven't crunched those numbers.

 

[Garbz]

Quote:

Originally Posted by MASantos Garbs you spoke about placing two ferrite beads "down the line". I supose these should go after the output capacitor of the LM317? What specs should I aim to?

They are ferrite beads. Most do not come with any specs as such since the inductance is really low. Anywhere near the audio spectrum they look like, and are a plain wire going through a donut

If you have a metal case you WILL earth the case, there is no should about it. It is not some thing that is recomended. It is an essential safty device. You WILL always ground a metal case that contains mains voltages, and you WILL NEVER defeat the ground of a metal case regardless if it makes you DAC-AH sound better or not. Mind you this is not a mistake you repeat. Natrual selection makes sure of that.

If you do not fuse it at worst your transformer acts as a fuse and cooks, or your 10A mains fuse blows if you short your L to N. You can find IEC plugs with fuses in them.