Power Supply with Switching Pre-Regulator

[MrAl]

Hi there,

UPDATE:
Complete parts list on the way...about an hour from now /ubbthreads/images/graemlins/smile.gif
New schematic with several small changes...Check back.

koala:
No not too late to join, welcome! There's about 4 or 5 of
us building this power supply now.
Yes, the variable circuit will go 0-30vdc, 0-3 amps with a 30vac transformer.
The 30vac gets rectified to dc first.
There are various current limiting methods...
First there is the set point (via coarse current set) which forces
the output to be limited to whatever you set it for (2 amps perhaps?).
Second, there is limiting internal to the LM317/350/338.
Third, there is limiting internal to the switcher ic.
Fusing is a good idea, primary and secondary.
Your part substitutions look ok to me (1N4004 diode too) but double
check the new parts with the newest schematic as some small changes have
occurred.
If you'd like to power the meter with the existing supply, we *might* be
able to rig up two or so caps and some rectifiers that will run the meter.
Would you like to try this so you dont have to use batteries?
What kind of programming you do if you dont mind me asking?


Pablo:
Still doesnt work. Cant delete or add new schematic.
BTW, you'll have to update your schematic with this new schematic, and you
may want to check for errors because i saw a shorted cap, no ground for
one cap, and a few other things...might want to go over it?

Vic:
No didnt get any parts yet. How where they shipped?




Take care,
Al

 

[koala]

Thanks for the help. I probably won't start building until I could find the LF412A Dual op-amp.


Offtopic What kind of programming? I am a pretty young programmer.

Currently
vb.net, perl, cobol

Previous commercial experience
c, c++, java, asp.net, php, python

Personal interest
Bash shell, Atmel AVR asm, Microchip PIC asm

RIP / rusty
Basic, Lisp, flex, bison, motorola mc64k

 

[MrAl]

Hi again,

koala:
Ever hear of a language called Euphoria?
BTW, dont bother with the 'A' version of LF412.
Go for the non A version as it's a lot cheaper.
The Schematic is updated by Pablo did something to the
site so i cant upload the new schematic. He'll have
to fix it before i can post it.


UPDATE

Here's the parts list. There's two parts.
Part 1 deals with every version, while Part 2
is for specific versions.

PART 1

All resistors 1/4 watt, 5 percent unless otherwise indicated.


Parts list, all versions

R1 1k
R4 100 ohms
R5 10k
R6 10k
R7 10k
R9 1k pot
R10 100 ohm trim pot
R11 47 ohm
R13 4.7k
R14 4.7k
R16 100 ohm pot
R17 100 ohm
R18 4.99k, 1%
R19 4.99k, 1%
R20 4.99k, 1%
R21 4.99k, 1%
R22 10k trim pot (adj for approx 5k and 5k)
R23 10k trim pot (adj for approx 1k and 9k)
R24 100 ohm


C4 0.1uf, 50v ceram disc
C5 0.1uf, 50v ceram disc
C6 100uf, 25v electro
C7 10uf, 15v electro
C8 0.1uf, 50v ceram disc
C9 10uf, 35v electro
C10 0.01uf, 50v ceram disc
C11 10uf, 35v electro
C12 10uf, 35v electro
C13 10uf, 35v electro
C14 0.1uf, 50v ceram disc

IC3 78L15 voltage regulator
IC4 79L15 voltage regulator
IC5 LF412
IC6 LF412

D1 1N5402
D2 1N5402
D3 1N5402
D4 1N5402
D5 1N4003
D6 1N4003
D9 1N4739A (9.1v zener)
D11 1N5225 (3v zener)
D12 1N4148

VR1 LM385Z-1.2
VR2 LM385Z-1.2

Q1 2N4403 or similar
Q2 2N4401 or similar
Q3 2N4401 or similar

LED1 20ma, any color LED



PART 2

--------------------------------------------------------------------------

20v output version parts

T1 Transformer with 24vac secondary
R2 18k
R3 2k pot
D7 (jumper)
D8 (jumper)
C1 100uf, 35v electro
C2 47uf, 35v electro
C3 470uf, 35v electro
Cin 35v electro (see also below output current selection)
Cout 35v electro (see also below output current selection)

--------------------------------------------------------------------------

30v output version parts

T1 Transformer with 30vac secondary
R2 27k
R3 2.5k pot
D7 1N4747A (12v zener)
D8 1N4747A (12v zener)
C1 100uf, 50v electro
C2 47uf, 50v electro
C3 470uf, 50v electro
Cin 50v electro (see also below output current selection)
Cout 50v electro (see also below output current selection)

--------------------------------------------------------------------------

1.5 amp output version parts

D10 3A Schottky, 1N5822 (20v version) or MBR350 (30v version) or similar
R8 6.2k
R12 10k trim pot (adj for approx 3.9k)
R15 0.1 ohm, 1/2 watt
IC1 LM2576-adj (20v version) or LM2576HV-adj (30v version)
IC2 LM317 (20v version) or LM317HV (30v version)
L1 200uH inductor, peak I=2.5 amps
Cin 2 x 1000uf (see also above output voltage selection)
Cout 1000uf (see also above output voltage selection)

--------------------------------------------------------------------------

3.0 amp output version parts

D10 3A Schottky, 1N5822 (20v version) or MBR350 (30v version) or similar
R8 2.7k
R12 10k trim pot (adj for approx 3.3k)
R15 0.1 ohm, 2 watt
IC1 LM2576-adj (20v version) or LM2576HV-adj (30v version)
IC2 LM350 (20v or 30v versions)
L1 200uH inductor, peak I=4 amps
Cin 6 x 1000uf (see also above output voltage selection)
Cout 3 x 1000uf (see also above output voltage selection)

---------------------------------------------------------------------------

5.0 amp output version parts

D10 SB550 or similar (5A, 50v Schottky)
R8 1.5k
R12 10k trim pot (adj for approx 2.2k)
R15 0.1 ohm, 5 watt
IC1 LM2678-adj (20v or 30v versions) with added C boost=0.01uf 50v ceramic cap
IC2 LM338 (20v or 30v versions)
L1 47uH inductor, peak I=6 amps
Cin 10 x 1000uf (see also above output voltage selection)
Cout 5 x 200uf (see also above output voltage selection)

--------------------------------------------------------------------------

 

[PEU]

Edited: It's working again, take a look at the bottom of the Powersupply section /ubbthreads/images/graemlins/smile.gif

Al, working on it, I'll install a new version of the software that resolves this very problem.
Pablo

 

[MrAl]

Hi Pablo,

Say hi to Tao for me /ubbthreads/images/graemlins/smile.gif

I tried the site and it's still not working.
Now, i can delete the old image but when posting
a new one with the same name (update) it uses the
old image not the new one.

Take care,
Al

 

[PEU]

Hi Al, is Teo /ubbthreads/images/graemlins/smile.gif

I sent you a PM and wrote some lines at the bottom of the power supply page.

/ubbthreads/images/graemlins/popcorn.gif

Pablo

 

[MrAl]

Hi Pablo,

Oh, Teo ok, sorry. That's a cool name! Is there any
translated equivalent into english by any chance?

Thanks for looking into the wiki problem.
I've sent PM too.

We're about done with this circuit now until the
breadboard gets up and running.
I've been looking into some replacements (even for lower
current versions) for the switcher ic, and found a few
interesting ones that may be even more efficient.
Im not looking for super great eff here, but i do want
to reduce heat as much as possible so i can put mine
in a small box without extraordinary cooling stuff
(like fans).


Take care,
Al

 

[PEU]

Hi Al,

The exact translation of Teo is Theo /ubbthreads/images/graemlins/smile.gif

the circuit is now visible, I'll update the expressPCB schematic to reflect the changes and will post a pic for review.

/ubbthreads/images/graemlins/popcorn.gif

Thanks


Pablo

 

[vicbin]

Great, more CPRer are joining the club ! /ubbthreads/images/graemlins/smile.gif

G'day Vince,

Wellcome ! /ubbthreads/images/graemlins/smile.gif
Thanks, yeah that comics was supposed to freshen that long serious discussion. I think it's time to make the new one here, before this thread going to heat up since Al is finalising the circuit ! /ubbthreads/images/graemlins/naughty.gif


Pablo,

I'm planning to use Eagle CadSoft since it is built in with trace autorouter ! /ubbthreads/images/graemlins/cool.gif

A bit difficult to use compared to ExpressPCB but it will save me from trouble of wrong route or forgotten trace since I'll change abit from the original Al's design.

There is now a new version and a free and fully functional version with the only limitation of board size = 100 x 80 mm (4 x 3.2 inches) and max. 2 layers board. I think this limitation is more than enough for this PS project. /ubbthreads/images/graemlins/smile.gif
Btw, I'm from Indonesia, ever heard it before ?
You'll have to dig across this earth to reach me ! /ubbthreads/images/graemlins/wink2.gif /ubbthreads/images/graemlins/poke2.gif


Hi Al,

What possible replacement for the switcher IC are you talking about ? Higher efficiency yet simple & affordable ? ....drool..... /ubbthreads/images/graemlins/drool.gif

Interesting issue, about the heat reduction, example from the thermal resistance value from datasheet :

LM317 - TO220
Junction to case = 3 Celcius/Watt
Junction to ambient (no heatsink) = 35 Celcius/Watt

LM338 - TO3
Junction to case = 1 Celcius/Watt
Junction to ambient (no heatsink) = 35 Celcius/Watt (why same as LM317 ?) /ubbthreads/images/graemlins/thinking.gif

Let say with 3 Volt dropout across and with 1 Amp current (dissipation : 3 x 1 = 3 Watts), do we need a heatsink ? How to calculate this heat formula ?

Update:
Suggestion, you can use this free image hosting -> ImageShack <font color="red">just for temporary</font> and when problems is gone, you can re-edit the image URL back to Pablo's site. Just to remind you since it is free, no guarantee it will be there for a long time.

Regards,
Vic

 

[PEU]

Hi Vic,

I downloaded eagle, but as you said is bit more difficult, autoroute is niiiiice, may be is worth the extra learning work..., I guess the netlist works for eagle too.

the server problem is IHP related, so I must wait for them to solve it... /ubbthreads/images/graemlins/frown.gif


Pablo
PS: IHP internet hosting provider

 

[vicbin]

Hi Pablo,

Yep, that software is very powerful, it supports advanced management features like scripting, bill of material, cost, customized library, etc..etc ... tons of other features that I don't understand what are they for ? /ubbthreads/images/graemlins/grin.gif

The bad news for me is I just downloaded their "tutorial documents" few days ago ! /ubbthreads/images/graemlins/mpr.gif Time to squezee my brain ! /ubbthreads/images/graemlins/banghead.gif

Oh, so its your IHP fault, you should demand a compensation for the downtime ! /ubbthreads/images/graemlins/whoopin.gif /ubbthreads/images/graemlins/Christo_pull_hair.gif ..he..he..

Regards,
Vic

UPDATE :
Pablo, I think there are 2 mistakes at your converted schematic here -> Power Supply Schematic file for ExpressPCB
Both voltage reference LM385-1.2 VR1 and VR2 should be reverse biased instead of forward biased (like ordinary diode). Just rotate 180 degrees for both of them ! /ubbthreads/images/graemlins/grin.gif

 

[PEU]

Al: Well the IHP guys did their job, and the problem is solved (at least in my tests).

Vic: thanks, I connected them like diodes /ubbthreads/images/graemlins/smile.gif reading the spec sheet I see that they used a zener symbol but reversed ¿?¿?

Updated both MrAl.sch and MrAl.jpg (use the same 1st links I posted above)
Did you found some other error?

BTW, expressPCB does not allow exporting the netlist /ubbthreads/images/graemlins/frown.gif so I'll route manually the whole board /ubbthreads/images/graemlins/smile.gif


Pablo

 

[PEU]

Hi, I have some questions that popped up while placing components in the PCB:

for Vic:
-what are the Cap (Cin & Cout) dimensions?, I need the lead spacing of the 1000uF ones

for Al:
- Which parts need dissipation, and how big?

I will update these three links while making the board:

Schematics JPG / Schematics / PCB

The switching part is already done, comments are welcome!


Pablo

 

[MrAl]

Hi again,


Vic:
LM26xx types, with DMOS output transistor look interesting.
Maybe you mentioned these already?
Yeah, the LM317/x/x reg's will still require some heatsinking, but
i was thinking in the future go to low dropout so we can keep the
heat even lower. Hopefully find a 5 amp version with low dropout.

The heat formula is pretty simple. An approximation is one square
inch per watt per (approx) 60 deg C rise. Since i dont want my hs
hotter than 60 deg C above ambient, i need one square inch per watt.
This is min for me. At 3 amps and 3.6v drop (LM3xx linear) that means
at least 11 square inches surface area for heatsink, but the more the
better.

Pablo:
OH yes, the site seems to be working again, thanks.
On the new schematic there are diodes changed, D11, D7, D8.
Saw your pic of your son Teo ... cute! hee hee. How old is he now?
We're looking at different size heat sinks for the different output
current versions... would you like me to try to find some on the web?
or just specify the surface area?
Your schematic is coming along very nicely!


Take care,
Al

UPDATED:

 

[vicbin]

Hi Pablo,

Thanks for the updates ! That is very nice of you ! /ubbthreads/images/graemlins/smile.gif

My 1000uF/100V cap dimensions :
Diameter : 18mm
Length : 41mm (lead not included, cap body only)
Lead size : 0.75 mm
Distance between two leads : 7 mm

Some suggestions and considerations on PCB design, and it is more applicable for "through hole" type only, for SMD it is h*ll a lot easier, since all nowday they're quite uniformed & standarized in size :

1. Make sure you have the accurate dimension in hand , download the datasheet first if you know exactly which type <font color="red">AND</font> brand of the component, for me I buy them first before PCB design cause some type of components can vary in sizes and also looking at my "supplier" conditions, I can not afford not to buy them first ! /ubbthreads/images/graemlins/frown.gif

2. Capasitor, different voltage rating will have different size and one thing I noted is sometimes even on same uF/volt rating, they're "slightly" variation among different brands. /ubbthreads/images/graemlins/frown.gif Oh yeah, to make thing worst, it is common that low ESR cap are bigger (some are taller or some are fatter) than ordinary one.

3. Inductor, was one of my nightmare in the past because I was winding them myself, since I can't be sure which correct inductor to use, sort of trial and error because I don't have a scope /ubbthreads/images/graemlins/frown.gif . Although finally it is working, the final result was a big mess ! Imagine what I've been through...... test, yuck, desolder, rewind, solder, test, yuck, desolder, change core, rewind, solder, test ,yuck, change core...and so on...and so on........ arrrghhh...... /ubbthreads/images/graemlins/mad.gif /ubbthreads/images/graemlins/Christo_pull_hair.gif /ubbthreads/images/graemlins/xyxgun.gif I believe you can imagine how is the PCB looks like ? /ubbthreads/images/graemlins/grin.gif

4. Heatsink, I think you already know what I mean don't you ? /ubbthreads/images/graemlins/smile.gif For LM2576/TO220 especially you're planning for 3 Amps, it is a must, I used this types of heatsink pics below for most of my TO-220 components :

Remember, we're planning to use the TO3 sized LM338 at the linear part ! /ubbthreads/images/graemlins/crazy.gif That will be another beast to consider ! /ubbthreads/images/graemlins/grin.gif

Ok, now comments on your PCB design :

- The schottky diode, looks like it is way too small (like a 1N4148 to me ? /ubbthreads/images/graemlins/grin.gif ). Remember, I suggest you need at least a TO-220 sized one. Look at my component pic from previous post for B1045/MBR1045, I put a thin & small one, since "most of the time" schottky diode won't heat up too much , just barely warm.

- R1 & R2, why they're different in size ? For those voltage divider feedback, 1/4 watt is enough.

- Inductor, there is no way it is that small, looks like 1/2 watt resistor. /ubbthreads/images/graemlins/smile.gif
Pics of my inductor with a 5mm led, the same type that I used for my 1st LM2576.

One is flying to Al and he will test it for me ! Thanks sensei ! /ubbthreads/images/graemlins/grin.gif

Pablo, again these are only suggestion and what I've been through. Other comments from other CPFer are wellcome. /ubbthreads/images/graemlins/smile.gif


Hi Al,

I've seen the new circuit with CC led, thank you ! /ubbthreads/images/graemlins/smile.gif

Now, question on how it works and why there are some other components added ?

What happened if that LED got disconnected by accident ? "Only" current regulation will be gone right ?
The reason I asked is because it is likely this LED will be placed on panel with some connector/wire instead of soldered steadily on the PCB. Again, just a thought and prolly nothing serious ? Am I too paranoid ? he..he...

Now I can imagine how the heatsink will looks like , thanks. /ubbthreads/images/graemlins/smile.gif

About the new regulator with DMOS, yes I've mentioned it in the past but I decided to skip it first since they're running on high frequency. "A lot" of PCB consideration needed, also read my experience above on core. /ubbthreads/images/graemlins/smile.gif

One of the LDO I'm looking at is LM1084, max 1.5 volt drop at 5 Amps. Is it suitable ?

Regards,
Vic

 

[PEU]

you're right Vic, I'll purchase the components before wasting time in a pcb that will need to be redesigned. This will delay at least a week, but hey, there is no hurry /ubbthreads/images/graemlins/smile.gif

Thru hole PCB's are very expensive here, I just called a provider and they asked about $100 for a single board!!!

So I'll try hard to use a single layer pcb or at least a double layer with no thru hole.


Thanks


Pablo

 

[MrAl]

Hi again,

Yes Vic, the size is nice to know before making the PCB, but there are
a few parts that maybe a few different sizes could be used. For example,
the sense resistor could be 1/2 to 10 watt version if there are several
holes for short, medium, and long resistors.

The heaksinks could be mounted off board too. In one battery charger design
i did the power transistor was mounted on the alum case (with isolation
hardware) and three leads run to the pcb.

The schottky diode changes with version too, as some of the other parts also do.

The CC Led turns on whenever the op amp detects overcurrent and
drives that transistor on. The LED get's current flow so it must
turn on. If you're worried about it coming disconnected and causing
a lack of current control (very good point) we can add one 2N4401 and a
resistor to allow it to be driven independently, if you like that idea
better. I tried to use min parts for the LED drive originally.
Voltage control isnt affected if LED becomes disconnected.
One idea for the mounting of this LED is to have it mounted on the very
edge of the pcb so it can protrude out through the front case. This means
shortest leads.

Yes, the DMOS switchers LM26xx are 260kHz. Advantage is also smaller
inductor. As you can see from the parts list i made, this results in
a smaller 47uH inductor.

Oh yes, LM1084, which i was looking at too Looks like this would
reduce heat my 50% or so, which reduces heat sink to 1/2 size.

Extra parts? Do you mean the 100 ohm and 0.01uf cap? This was added
for extra stability with capacitive load, and keeping transient V overshoot
to almost zero with cap load.

Pablo:
Different sense resistor sizes are used with different versions, and
Schottky diode changes too. Review the parts list i posted to find
out what your version requires ok?


Take care,
Al

 

[vicbin]

Hi Al,

Yes please, show me how to drive the LED independently. /ubbthreads/images/graemlins/smile.gif

From the LM317 datahsheet, there a note about protection diode across the Vin and Vout to avoid the damage when there is a short circuit, is it needed in this version ?

Also there is a note that a minimal load/output current required to maintain regulation, since the voltage loop is controlled by the external op-amp, do we still need it ? In my previous experience, the requirement for minimal load actually came from the switcher !

I'm thinking to do the PCB in 3 modules which are capasitors part(bunch of Cin), switcher part and linear part, and if possible, I'll make those 3 boards equal size so I stack them ! /ubbthreads/images/graemlins/smile.gif

I remember in the past you mentioned something like double inductors & capacitors for reducing ripple, how is that ?

Say if I want to place a LC filter, where is the suitable place for them ? Is it between the Cout and R2 (switcher out) or between R6 and C8 (linear input) ? Planning to reserve a space and pads for the "optional" LC filter. /ubbthreads/images/graemlins/grin.gif

On the DMOS switchers LM26xx, is it still possible to use the ordinary caps ? Since paralled big caps such like mine might have some distance from the switcher while from their appnote, it is clearly mentioned the power switching path must be very-very short, below 1 inch if I'm not mistaken. /ubbthreads/images/graemlins/frown.gif
Is it possible for you to measure the ESR of the ordinary cap ? e.g.: 1000uF


Hi Pablo,

Ouch !!!! How come the board cost $100 there ? /ubbthreads/images/graemlins/mad.gif Are we talking about an un-etched copper clad board ?

Here single sided copper clad board 20 X 10 cm cost $2 a piece, 2 double sided about $3.5 ! Your price there is way too much, want some help ? /ubbthreads/images/graemlins/smile.gif

Regards,
Vic

 

[MrAl]

Hi Vic,

The LED drive is now on the new schematic (see below).

That's a good point about the protect diode, i think we should add it.
I'll put one on the next schematic update. That's for when the input
gets shorted right? We might have a condition similar to that in some
case, so maybe it's a good idea.
The minimal load for the LM317 (and similar) is already taken into
account with the control circuit. As soon as you hook a 100 ohm resistor
to the output (and control through this resistor) you've satisfied that
requirement just about. If the switcher or even the two circuits working
together need a small min load, i think the breadboard can tell us better.
Also the switcher might require a small min load if the inductor causes a
problem at low current output.
Yes, Double inductors and caps for a two pole filter instead of single pole,
but i havent had time to try this yet because i've been busy with the
schematic and making sure everything is correct, like part numbers, and
other stuff that seems more important at the moment. In the past i did
some experiments that showed that a two pole filter might respond faster
than a single pole and that would be good for high voltage outputs, but
i havent gotten back to it yet. I'll eventually get to it but for now
it's sorta last because using the Simple Switcher the way it's shown
by National (single pole) at least we know already works, and the other
things like LED and just overall good operation were more important so
that took up my time.
Without looking closer, it does seem a small inductor/cap filter like
the data sheet shows should work without bothering too much. Just make
sure the resonate freq isnt close to the switcher's frequency (52kHz or
260kHz). The formula is fo=1/(2*pi*sqrt(L*C))
where sqrt() means to take the square root.
The best place is just before C8 on the schematic.
Break the line that leads from the switcher to C8 and insert there
(yes between R6 and C8).
It may be possible to use ordinary caps with the DMOS 260kHz switchers,
with perhaps a smaller low ESR cap close to the switcher with feedback
close too, then the remaining caps a bit farther away. I havent looked
at this too closely yet, but now that you mention it it should be looked
at carefully. Sometimes the low esr caps cause instability because they
make the LC tank look more underdamped.

You can measure the ESR of the cap(s), but usually you use a scope.
If you have high cap values on the output of the switcher, you'll see
the effect of the ESR by looking at the ripple voltage.
You can estimate the ESR by driving the cap with a square wave
of known voltage peak. The peak of the current wave shows the
ESR because the cap voltage doesnt change much. For example,
with a 1 volt peak square wave and 1 ohm series resistance you'll
see about 0.5 amps after the cap voltage ramps up to it's average
value of about 0.5 volts. This is because 0.5 volt divided by
1 ohm equals 0.5 amps. Pretty simple, and there's no reason why you
cant apply this technique once the switcher is operating by simply
measuring the peak output voltage with 50% duty cycle and measuring
the peak current through the cap.
Perhaps we can do the same by measuring the ripple voltage.
This might be possible using that 'Ripple Detect Network' i
talked about before. If there is I average amps through the
cap and there is v volts of ripple, than Rs is probably something
like v/I/2. I'll double check this later today.
The ripple detect network isnt hard to build either, a few small
cheap resistors and caps.


Take care,
Al

MOST RECENT:

MOST RECENT PARTS LIST, PART 1:
All resistors 1/4 watt, 5 percent unless otherwise indicated.


Parts list, all versions

R1 1k
R4 100 ohms
R5 10k
R6 10k
R7 10k
R9 1k pot
R10 100 ohm trim pot
R11 47 ohm
R13 4.7k
R14 4.7k
R16 100 ohm pot
R17 100 ohm
R18 4.99k, 1%
R19 4.99k, 1%
R20 4.99k, 1%
R21 4.99k, 1%
R22 10k trim pot (adj for approx 5k and 5k)
R23 10k trim pot (adj for approx 1k and 9k)
R24 100 ohm
R25 8.2k
R26 1.5k


C4 0.1uf, 50v ceram disc
C5 0.1uf, 50v ceram disc
C6 100uf, 25v electro
C7 10uf, 15v electro
C8 0.1uf, 50v ceram disc
C9 10uf, 35v electro
C10 0.01uf, 50v ceram disc
C11 10uf, 35v electro
C12 10uf, 35v electro
C13 10uf, 35v electro

IC3 78L15 voltage regulator
IC4 79L15 voltage regulator
IC5 LF412
IC6 LF412

D1 1N5402
D2 1N5402
D3 1N5402
D4 1N5402
D5 1N4003
D6 1N4003
D9 1N4739A (9.1v zener)
D11 1N5225 (3v zener)
D12 1N4148
D13 1N4742 (12v zener)
D14 1N4148
D15 1N4148

VR1 LM385Z-1.2
VR2 LM385Z-1.2

Q1 2N4403 or similar
Q2 2N4401 or similar
Q3 2N4401 or similar
Q4 2N4401 or similar

LED1 20ma, any color LED

 

[PEU]

Al: time to update my schematics /ubbthreads/images/graemlins/smile.gif
Vic: $100 is the cost of a fully etched double size, metalized thru hole board, not a simple bare one !!! /ubbthreads/images/graemlins/smile.gif

Pablo