Mmini regulator (sample offering)

[Vidalgo]

Well, my boards arrived, thanks!
Manufacturing quality is excellent. The purple one looks very sexy.
Start sourcing components.
Planned to build at next week or two.

 

[bigmike216]

I also agree about the quality of the boards! I'm sourcing components now too, will be building soon!

 

[carlosfm]

Many thanks to Coffin for graciously providing the sample boards.

May I join you?
Thanks, Coffin.

Received my boards some days ago, good quality PCBs indeed.
Well, as I needed a little more 'flexibility', I used 2.2K trimmers, paralleled with 10K 0.6W film resistors, for R2 and R12.
1K 0.6W film for feedback.
This way I can easily adjust for the range I wanted to, that is, between +/-12V and +/-18V.
I used one of the holes of the unused caps, C7 and C17.
The adjustment works well, but if I had space I would use a series resistor with the trimmer. Because the adjustment is wider than what I needed.
Also, I'm using the 5.0V LM336, and a lower gain on the op-amp (OPA627BP).
For ZD1 and ZD2, I'm using 10V/1W zeners.
EDIT: I'm using Elna Silmic 100uF/25V output caps. Diodes are MUR1100.

Here it is.

 

[carlosfm]

The Frako caps give it a 'retro' look.

 

[bigmike216]

I'm sourcing parts now.

I've decided to go with 24v for the positive board, for a headphone amp. I'm having a bit of trouble finding the 2SK170. Are there any possible substitutes? Or does anyone have some that'd be willing to sell me 5?

 

[izzyman]

substitutes

I used these subs & they work fine:

Q1: MJE15030
Q11: MJE 15031

 

[bigmike216]

the 2sk170 is Q5 on the positive, and and Q5 and Q15 on the dual.

 

[carlosfm]

I'm having a bit of trouble finding the 2SK170. Are there any possible substitutes?

I used 2SK170GR, but here's what you can use as substitutes:

2SK43, 2SK121, 2SK163, 2SK186

 

[izzyman]

woops...

Sorry 'bout that--I was doing this from my feeble memory & thought you were talking about Q1, not Q5
The version I built (+/-75v) doesn't use a transistor there at all, but a resistor.

 

[bigmike216]

Coffin had posted it a few pages back, he has kindly directed my attention to that post. Can't believe I missed it.

 

[fixation]

Can i get a Sample too please? I really like them Hope that the're are still some left

 

[jerishi]

query

Hi, thought I'd check in here re; regulator boards, I sent the required postage/mailing address thru paypal 11-23 and haven't heard anything since then. Am anxious to try these w/chip amp project. Thanks in advance.

 

[Ryssen]

I got a sample PCB a while ago,now I am building a Krell KSA 50 clone and I found a trafo I could use for a regulared PSU for the front end...
How much current can the Mini reg give at +- 40v,if I change D1,D2,D11,D12 for 3A types,kan it give say 1-1.5 Ampere?

 

[Ryssen]

How low can I make R6/R16?

 

[coffin]

Hi
The recommended output current is under 1A.
But you can try to set R6/R16 using the formula :

R6 & R16 can set the current , R6=R16

Max output I = Q1 hfe* ( 1.8V / R6 )

example : Q1 hfe=80 , R6&R16=200R , Max output I = 80* ( 1.8V / 200R ) = 720mA

cheers

Coffin

 

[peranders]

Ryssen, please notice that the output voltage is the same as for the opamp. 40 volts is too much with most opamps. 30 or 36 V is max.

 

[Ryssen]

with most opamps. 30 or 36 V is max.

The OPA445 max voltage is +- 45v,the opamp was recomenden in the mini reg´s webpage.
I was told that the drivers for KSA50 would need max 0.5A per chanel,thats 1A for the regaulator if I make R6/R16 so I get 1Ampere max,doesn´t I need any headroom,just incase they would have to deliver more current?What will happend if I make the regulator deliver more than 1A?

 

[coffin]

Hi
Please change Q3/Q4 to 2SB649, Q13/Q14 to 2SD669.
mount them on the chassis to sink heat. don't forget to do the isolation.
Change R6/R16 to 75ohms.

It can afford 1.5A with no problem at all.

cheers

Coffin

 

[Ryssen]

Please change Q3/Q4 to 2SB649, Q13/Q14 to 2SD669

Ok,thanks,I´ll have to find some BD types here in Sweden.
It will be 1-2 months before I can test the amp.

 

[peranders]

Notice that BD139/140 have different pinning

I have some D44H11 and D45H11 if you want to test. If you really are goung to put 1-1.5 A through the BD's, it's a bit weak.