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  #1  
Old 19-05-10, 04:04 PM
mikesnowdon mikesnowdon is offline
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PCB for teddy's 'Regulator booster'

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....


Last edited by mikesnowdon; 19-05-10 at 04:19 PM.
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  #2  
Old 19-05-10, 04:07 PM
mikesnowdon mikesnowdon is offline
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Schematics to follow.....

78** Positive Reg Booster:



79** Negative Reg Booster:

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  #3  
Old 19-05-10, 04:12 PM
LoBo LoBo is offline
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I'd be interested in 317 and 337 regs. A strip of each?

This would be cool Mike. Nice one.
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  #4  
Old 19-05-10, 04:23 PM
mikesnowdon mikesnowdon is offline
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Cool.

Also, any ideas on the cheapest way to have these made and which company to make them?

Thanks
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  #5  
Old 20-05-10, 07:24 AM
Herat Herat is offline
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I'd be interested in 317 and 337 regs too, 1 or 2 pos and neg

Thanks

Ronald
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  #6  
Old 20-05-10, 09:03 AM
Bemused Bemused is online now
What's this all about then?
 
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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
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Possibly had a glass of wine or two.
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  #7  
Old 20-05-10, 09:12 AM
PigletsDad PigletsDad is offline
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It boosts the rejection ratio, especially at high frequencies where the 3 terminal devices fall away.
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  #8  
Old 20-05-10, 09:19 AM
martin clark martin clark is offline
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Simple and effective demonstration:

http://www.acoustica.org.uk/t/3pin_reg_notes2.html
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  #9  
Old 20-05-10, 09:21 AM
martin clark martin clark is offline
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Mike, do note for reasons of voltage drop and limited collector current that really will only be good for load currents under 50mA.
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  #10  
Old 20-05-10, 09:22 AM
mikesnowdon mikesnowdon is offline
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I have used this circuit on the 4 local 7805's powering my DAC chips and the effect wasn't subtle
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  #11  
Old 20-05-10, 09:23 AM
mikesnowdon mikesnowdon is offline
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Quote:
Originally Posted by martin clark View Post
Mike, do note for reasons of voltage drop and limited collector current that really will only be good for load currents under 50mA.
Unless a smaller resistor and appropriate pass transistor is used?
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  #12  
Old 20-05-10, 09:28 AM
mikesnowdon mikesnowdon is offline
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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?
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  #13  
Old 20-05-10, 09:39 AM
martin clark martin clark is offline
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No, that'll work nicely
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  #14  
Old 20-05-10, 09:43 AM
neiljadman neiljadman is offline
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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.

Last edited by neiljadman; 20-05-10 at 11:04 AM.
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  #15  
Old 20-05-10, 10:14 AM
neiljadman neiljadman is offline
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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...

Last edited by neiljadman; 20-05-10 at 10:25 AM.
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