REGULATOR PSU protel layout share

[digi01]

scratch VER#1.0

pic review here.



the PCB boards size as big as my 3886igc


-digi

[digi01]

the zip is protel99se project file,for free

[digi01]

modify 1

[carlmart]

Before discussing pcb, it would be a good idea to know which schematic you are using and to put it on this thread.


Carlos

[digi01]

the pcb can mounting TO-200 or TO-3 types chip.
sch file:

[carlmart]

Originally posted by digi01
the pcb can mounting TO-200 or TO-3 types chip.
sch file:

First of all provide protection diodes as is suggested on the LM317 datasheet.

Second, the output capacitors should be smaller, at least on the 338. Look at Carlos findings on how the 3886 sounded when the regulator used smaller caps. He put a film cap at the 338 output and a small 'lytic by the 3886.

If you are going to design a pcb, also provide pads for a resistor instead of a trimpot. After you set the voltage it might be better to use a fixed resistor.


Carlos

[sek]

Hi Carlos,

the output capacitors should be smaller

as stated in the LT108x datasheet, those ICs need a minimum capacitance at the output to ensure stability. It's good to provide an adjust pin capacitor too (as Digi has done), but this increases the required output cap size even further.

He put a film cap at the 338 output and a small 'lytic by the 3886.

I think the circuit is safe with the 220uF for the LT108x. As for the LM388, nobody forces one to put a big cap in. But it's wise to provide the board space.

Sebastian.

[carlmart]

Originally posted by sek

as stated in the LT108x datasheet, those ICs need a minimum capacitance at the output to ensure stability. It's good to provide an adjust pin capacitor too (as Digi has done), but this increases the required output cap size even further.

There are very few comments to get use info about the LT108x chips on this forum. So I wouldn't risk going too high without trying and listening. Adjust pin cap is certainly good, and it's there where you can go high, not at the output. You will need protection diodes there, though.

In fact I think diode protection should be used between: input/output, adjust pin to to output, and output ground. Though the latter is not necessary if output cap is small.

I think the circuit is safe with the 220uF for the LT108x. As for the LM388, nobody forces one to put a big cap in. But it's wise to provide the board space.

Providing space is nice if you have it, particularly because you can try film caps if capacity is small and go for better quality. On the 338 you should try first what people used here and seemed to work better: small caps. Then see what works better for you.


Carlos E. Martinez

[digi01]

oooop!!
modify 2

thank you Carlos and Sebastian I have optimized some parts rooms.






H.B

[digi01]

main components mounting details:

U ,regulator chip
the board can mounting to-220 or to-3p types.

DIODE
each one,the foot distance is 400mil ,10.16mm.

C2
foot distance 300mil/400mil,7.62mm/10.16mm.
radius max=16mm
leg holes 2mm
can mounting common audio quality caps.

Rtrim
it is for setting the output voltage, the range is from 20V to 32V.
the board pads can moungting a resistor or a trimpot.as Carlos motions,after you set the voltage it might be better to use a fixed resistor.