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regulator booster

So I take it the schema above for a neg reg booster is pukka then? If anyone could confirm that would be much appreciated. Cheers :)
 
It rather depends on how you've drawn the PNP Mike! It needs raw -Vin on its Collector, and Emitter to pin 2 of the reg. Otherwise fine.

557s work fine; the A/B/C is the 'bin' of current-gain (hfe) the part made at test current - 'C' being the highest. This gives lowest dropout voltage, because it requires the least current through R1 to drive the load current.
 
Cheers Martin.

The PNP is drawn per the standard way a PNP is drawn, like this. I beleive I have the negative reg booster spot on then! :)

Puffin, build one and tell me if it blows up on not! :D
 
Cheers Mike!

C'mon, get your PCB's done, I'll definately have a bucket load and I'm sure others would too. I know strip boards are easy but you canny beat a pcb.

I'd front some cash for the manufacturing.

Do it, then do it again, and when you've done, sell me some!!!!:D
 
Would someone be prepared to show me a layout for a 5V LM317 reg booster?

Can a BC550C be used instead of the BC547C?
 
Excellent Mike, the pins are the same so will try this.

What about the transistors? The gain bandwidth is higher on the 547's what considerations are there for using 550's?

I have plenty of BC550C's. If they cannot be used instead of the 547's would anybody have a couple of 547's spare or like to swap for anything?

I think the circuit in which I am replacing one of the regs have to supply about 100-120mA and one about 70-80mA

Many thanks

Rich
 
I can send you a couple of BC547C's. But I dont know much about transistors so cant really advise on what alternatives there are.

Are you thinking of adding reg boosters to your DAC, the one you were having STR trouble with? If so you may need to use higher power transistors*.

EDIT: I got some nice gold plated right angle header pins from eBay (see my pics in previous post above). There is a link to the seller a few pages up.

*That is if the existing 317's run fairly warm. In earlier posts MC suggests that if the existing 317's run hot or are on fairly large heatsinks a power transistor is necessary to replace the BC547C. If they are cool then the 547 should be fine.
 
Yes Mike the DAC is the one... bloody thing.

Teddy mentions BC639 as a higher current alternative. Is this correct?
 
I think so, if he suggests that then I would go with the 639.

Good bang for buck with this mod. Gave me fantastic results added to the LM7805 powering my Wolfson WM8740 DAC. Suddenly I had really good timbral detail! Try the Nichicon MUSE KZ for post reg smoothing. They work well and help keep the reg stable. I originally had Rubicon ZLH after the boosted regs and changing to KZ really brought the music to life and made it sound much more analogue ;)
 
Thought I'd go ahead and try this using Mike's layout in post #73.

http://s779.photobucket.com/albums/yy75/RichLund/?action=view&current=IMG_1906.jpg

Electrolytic is 10uF Elna cerafine (I have no KZ's), Film cap is 2.2uF wima MKS. Transistor is BC550C. Resistor is 10K

Is the the electrolytic orientated with negative at adj / gnd?

The 317's they are replacing have 430R and 140R setting resistors in the DAC reg circuit. Do I leave them in place?

Thanks
 
Your RB looks fine but the layout wont work with a 317 (my layout is for using the RB on a 7805 reg) as the pinouts are different:

317 Adjustable regulator.

LM317.jpg


7805 (7815, etc) Fixed regulator.

LM7805-Pinout.jpg


You could remove the associated 317 external components from the DAC, find a ground connection for the middle pin of the RB, then replace the 317 with a 78** reg of the required value.

Or re-build the RB to suit the pinout of the 317 reg. Note that when using the 317, you will need to make a ground connection. See Teddy's original post.
 
Another thing. Check the pinout of the 550C and compare to the 547C. Its back to the drawing board I think :D If you need a hand PM me and I'll send my phone number so you can give me call.
 
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