SL-1200 DC Power Supply DIY

[6L6]

All this talk of the tracking pre-reg makes me really want to try it!

[NRG]

By the way, I ve been playing around with the preregulator thingy and I came up with this schematic

Attachment 10715

Basically I added the filter caps, the protection and thermal drift diodes and selected a few values for components. Oh and R3 should be 100R.

Any comments?

Make C2 10uf and lower the damping resistor. Use standard ESR cap not a super low ESR cap. The output cap is too small, again use a standard ESR cap 10 or 20uf. Take the ground connection of second regulator to the load along with the + feed, run a second ground connection back for the load to the first reg. Use LM117 or one of the LT regs instead of the 317

[richluvsound]

[QUOTE=NRG;469156]You can usefully improve this circuit by increasing the current through the Zener, with R1 at 240R you are only passing 5.2mA. The Zener impedance and noise will drop further and the LM317 will work better if you use the recommended value of 100R for R1...this will increase the current to 12.5mA, the Zener dissipation will rise to 240mW but its well within its rating.

You can increase the output voltage a touch and get temperature compensation 'thrown in' by placing a normal diode in the ground leg of the Zener, this will raise the voltage from (19.25+1.25) 20.5v to 21.1v....all as per the acoustica.org.uk site.

Hi, Gents,

please forgive my inexperience evident in the mundane questions .... I'm following the single reg schematic and have 19.9 VDC at the out put . When you refer to using a " normal diode" I'm confused ... could you be more specific please ?

thank you for your patience .

Rich

[6L6]

Don't worry about the 'normal diode' and do check the datasheet for the pinout of the device...

[richluvsound]

I now have 20.25 vdc on the output !

As always Jim , I greatly appreciate your time and good grace . That will be 2 pints me thinks


Rich,

[6L6]

Wonderful!

Do you have any more photos of your (very) nice looking enclosure?

[dimkasta]

BTW doing some experimenting with a LED reference I noticed that my test circuit was pulling way too much current, the leds were flashing, so I looked up for alternatives.

It appears that LM350 is a direct replacement, is ~3 times cheaper, has 5db better ripple rejection than the LM117 and can give 3A. So from my point of view it is a no brainer... I wish I had seen it earlier and included a few parts in my previous order...

[NRG]

The LT 117 figures appear to be the same but the noise is worse on the 350

[richluvsound]

Wonderful!

Do you have any more photos of your (very) nice looking enclosure?

For Jim

[Qwin]

Very nice enclosure