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Scalable PSU/regulator GB

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#47
JensRasmussen said:
May I suggest soldering a resistor on the bottom side if extra trimming is needed 😉

No point making a big problem out of nothing - IMHO

\Jens
Click to expand...
Jens, not a big problem really but I try to when it's possible to add optional parts because I don't like parts pacthed in here and there. Compare the work to fit in a LM431 if you thought of a LM329 in the first place. It's better to make a 4 pin part so both types will fit or simply have two footprints, one for the LM431 (and similar) and one for LM329 (or similar).
 
#48
The 431 is out of the question as the voltage divider needed for low voltage references will raise the output impedance a lot (lower loop gain) I prefer the 10V LM4040 as this allows for a voltage divider with more gain compared to the 431 (2.5V) divider

The capacitor in parallel with the emitter resistor has been removed as I found it was not needed for stability. For practical reasons I have left it out as the cap needed to actually do any difference was so big (>100uF) that I chose not to bother

Initially I wanted it to be there as a gain reducer at high frequencies…. I found it to be not needed and removed it.

\Jens
 
#49
JensRasmussen said:
The 431 is out of the question as the voltage divider needed for low voltage references will raise the output impedance a lot (lower loop gain)
Click to expand...
Really? You set the reference voltage at the value you like (from 2.5 volts up to 35V) and set the gain according to taste.

JensRasmussen said:
The capacitor in parallel with the emitter resistor has been removed as I found it was not needed for stability. Initially I wanted it to be there as a gain reducer at high frequencies…. I found it to be not needed and removed it.[/B]
Click to expand...
I think it is more like removing feedback at higher frequencies.
 
#53
Based on the preliminary schematic, here is a BOM. At current interest, the 15V parts kit for the board (both positive and negative regulators) will cost $16 without a trimpot. Using Bournes 3296Y multi-turn pots would add about $3.62/kit

For 12V use you could add a 100K trimpot and just dial down the voltage or swap R11 and R13

I just put parts in the order that they caught my eye, sorry.

D7,9______________________________LM4040-10___National

D1,2,3,4,5,6,11,12,13,14,15,16_________1N4004_____Diodes, inc

C4,5,31,32_________________________680uf/35v___Panasonic FC

C10,12,22,24_______________________470uf/25V___Panasonic FC

C6,7,11,13,16,19,22,24_______________1uf_________EPCOS

C1,2,3,8,9,14,17,18,20,21,26,29,30,34___100nf polyester film___EPCOS

C7,28_____________________________220nf polyester film_________EPCOS

R2,7,16,18_________________________10K_________Panasonic 1%

R3,4,5,19,20,21_____________________1K__________Panasonic 1%

R11,13____________________________2K__________Panasonic 1%

R6,10,12,17________________________330_________Panasonic 1%

R9,14_____________________________100_________Panasonic 1%

R8,15_____________________________22K_________Panasonic 1%

R23,24____________________________680*________Panasonic 1%

T1________________________________MJE15033G___OnSemi

T8________________________________MJE15032G___OnSemi

R1,22_____________________________1R 2W________Vishay BC

LED1,2____________________________LTL2T3TBK4 (blue)___Lite-On

T2,5,6_____________________________BC556C______Fairchild

T3,4,7_____________________________BC546C______Fairchild

* R24 and R24 are chosen to give ~15 mA LED current and keep their dissipation down to .15W. I don't care for full brighness of the LED (~400 mcd) and if you drop the resistor to 400R to get full brighness you need a 1/2W resistor, since the dissipation will be .3W. Space is a bit too tight for a 1/2 W resistor. Comments?

Also, the LM4040-10 is the 1% version. For $.75 more per kit, why use a 5% zener? Comments welcome again.

Trimpots in the kit?

Any comments on parts selection?
 
#55
Bob,

Nice work on the Bom, I have some changes.... sorry...

I will post a value list later, but will add no new types, just clean it up a bit so fewer different parts will be needed.

1A step response from the SIM:

\Jens
 

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#56
No problem Jens. It is a lot easier to delete line items than add, which isn't a big deal, either.

If there is a great divide between trimpot/ no trimpot, I might offer option of with/without. Please let me know your preference here.
 
#57
JensRasmussen said:
May I suggest to ask the other people that have signed up on the wiki what they would like and let the forum decide.

I'll wait for a reply from the people that have expressed their interest.

\Jens
Click to expand...


I thought the output voltage was Vref*gain(R5+R11/R11)?

If Vref = 2.5v, R5= 5K and R11=1K that should be 15v right?

Or am I missing something?
 
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