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PCB for teddy's 'Regulator booster'

M

mikesnowdon

resU deretsigeR
Myself and Anthony (aka G&JM) have been playing with the idea of a PCB that incorporates the 'Regulator Booster' using mostly SMT parts for minimal size and allows heatsinking of the regulator itself. We wanted it to be as 'drop-in' as possible.

We've only done 2 boards so far: A positive and a negative version using LM78** and LM79** series regulators as these seem to be the most common. If people want a 317 or 337 based version let us know in this thread. So far the boards are based on using a BC547 or 557 pass transistor. For higher current demand a BD139/140 can be used and I plan to add extra pads on he PCB so either transistor can be used on the same board (they have a different pin-out). There is also the option to have a LED power indicator. Resistors and LED are SMT case size 603. 1/4w resistors are available in this size. Tant caps are case style B allowing upto 35v rating.

As these are small we would be looking at doing them in strips like the TeddyRegs were done so maybe 10 per strip? Let us know what ratio of positive or negative VE boards you would like.

The main purpose of this thread is to have any possible improvements, corrections, or tweaks aired and to gauge interest with regard to a possible group buy.

Heres the layout....

regboosterimage.png
 
I'd be interested in 317 and 337 regs. A strip of each?

This would be cool Mike. Nice one.
 
Hi Mike, I have to be real stupid here and say I thought the booster was to get more current out of the regulator, but looking at your circuit the regulator still carries all the load.
What have I missed.
Tony
 
It boosts the rejection ratio, especially at high frequencies where the 3 terminal devices fall away.
 
Mike, do note for reasons of voltage drop and limited collector current that really will only be good for load currents under 50mA.
 
The idea is that the user can increase C2 and reduce R1 and sub the BC547C for a BD139. Then bolt the reg to a heatsink and all is good for higher current applications. Or leave it standard for lower current applications, circa <50mV.

Am I missing something?
 
Mike I see you used Expresspcb software. That locks you in to using Expresspcb for manufacturing since it is their own proprietary program. If you want to go outside ExpressPCB you'll need to redo the layout in a software that exports gerber files.

The only way to get the gerbers from Expresspcb is to pay them to send you the files - which they will do for about $60 - but only after you have placed a first order.
 
Also, why not go the whole way and use a BC847C/BC857C? The SOT23 packages are readily available and very compact.

I'm not sure if there's a SMT equivalent for the BD139 though...
 
neiljadman said:
Also, why not go the whole way and use a BC847C/BC857C? The SOT23 packages are readily available and very compact.

I'm not sure if there's a SMT equivalent for the BD139 though...
Click to expand...

Nice idea. It depends on the current rating. I'd like to make these as universal as possible. I wonder if there is a SMT transistor that would allow upto 500mA?
 
While were at it is there anything simple that we could do to further improve the output of the reg? Im wondering if its worth adding some kind of L/C on the reg output to filter any noise generated in the regulator itself, or at least ensure its nice and stable?
 
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