An other LM78XX regulator

[Koifarm]

😱

 

[EUVL]

So what is the footprint ?
Something like 20x18mm ?

Have you done any measurements, such as noise, Zout, PSRR, etc. ?


Patrick

 

[jxdking]

I used TL431 once a time.

 

[Koifarm]

Footprint is 25.4 x 26mm.
I have no experience with power supply measurements.
Only noise i can measure until -120db and that I measure.

I am also working on a 12 x 42mm version.

 

[Koifarm]

I think TL431 has more noise then LED’s.

 

[jxdking]

I think TL431 has more noise then LED’s.

That is true.
I tried TL431 to bias vacuum tube. Noticeable noise.

 

[Koifarm]

Post #1 updated with negative LM79XX regulator schematic.

 

[TNT]

Measurements (or sims) for output impedance vs frequency and noise vs freq would be welcome.

//

 

[Koifarm]

TNT, I have no experience with power supply measurements. I have USB audio test interface and ARTA software.
Noise 20 to 20khz is < 120db, because that is my interface limit.

Just ordered PCB for small version 12 x 30mm.

 

[Koifarm]

Today I received a view prototype PCB's. Started with the positive regulator.

I like the use of my hotplate for SMD soldering.
Just apply the solder paste.

Then place parts.

Heat up the plate and ready.
Just solder connector and T2 by hand

And testing

I will post also the Bom in post 1.

Next the negative voltage regulator.

Some prototypes

 

[zoom777]

Hello @Koifarm , I thought you have successfully done and tested the positive board in the first post? Is this positive supply board different from the one in post #1?

Hope to see update from you on the negative PSU board.

 

[Koifarm]

No zoom777, My first post I tested prototyp, made one changes on the Gerberfile.
Gerberfile is same as build now.

Test of the negative version have some faults I have to solve first.
Further I am testing the small form factor 12 x 30mm positive regulator as in pictures above.

 

[zoom777]

@Koifarm so it is now safe to use the Gerber file in post #1 to send for PCB printing? Thanks.

 

[Koifarm]

Yes

 

[Zoji6645]

Seems like the pass transistor base current is a little light. T2 has a min beta of 20 and T1 only supplies 5ma, so output current potentially is limited to 100mA. Safer to maybe run 10mA or more from T1. Drop R3 to 110 Ohm.

 

[Koifarm]

Thanks Zoji6645, I have mounted a 22ohm resistor at 12v to the output and the voltage dropped 3V. Hfe(beta) of my 2N6488 is 40 and there is also 7ma applied by the opamp. Max Iout is now about 400mA.

Origenal schematic had for T2 a MJE15032 with Hfe of 130. I can use the MJE15032 and drop R3 to 110ohm then it must be possible to get Max Iout about 2A.

Or replace D7,8 for a zener, then the opamp can apply more current.

 

[Koifarm]

This morning changed R3 from 220 to 120 ohm max A out rised from 400mA to 1000mA.

Changed value R3 in schematic post 1 and ad option 2A with MJE15032.

 

[Koifarm]

Updated post 1 with gerber files of negative regulator.
And updated schematic of negative regulator, R14 changed from 5k6 to 4k7 and R9 from 220 to 120 ohm.

 

[timgrindell]

Thank you Koifarm
tim

 

[zoom777]

Updated post 1 with gerber files of negative regulator.
And updated schematic of negative regulator, R14 changed from 5k6 to 4k7 and R9 from 220 to 120 ohm.

Does the positive regulator also need to reflect the change in the R8 resistance from 5k6 to 4k7 ?