Power Supply with Switching Pre-Regulator

[vicbin]

Hi folks,

Al,

Yes, finally..its here ! Its almost final right ? Or you still have other "hidden" kungfu blow to come ? /ubbthreads/images/graemlins/smile.gif

I'm also going to start breadboarding on the linear part soon !

Questions :

- Is it possible to increase the fine potentiometer to 500 Ohms ? While maintain the ratio of 10:1 to the coarse one, since 100 Ohms trimpot is easy to find but not for potentiometer here ! The lowest I can find is at 500 Ohms. /ubbthreads/images/graemlins/frown.gif I'm hoping it will not causing you trouble to change/adjust all other values. /ubbthreads/images/graemlins/blush.gif

- Is it possible to have a voltage trimmer as the current does ?

Finally, if you still have your typing stamina, "explain" the Voltage & Current control mechanism please ? /ubbthreads/images/graemlins/help.gif /ubbthreads/images/graemlins/bowdown.gif

My brain is starting slow and difficult to digest it ! /ubbthreads/images/graemlins/banghead.gif


Pablo,

What caps are you talking about ?


Crux,

Hey, thanks for that tips, you know in this kind of stuff, "THE DEVIL IS IN THE DETAILS" ! /ubbthreads/images/graemlins/grin.gif

Regards,
Vic

 

[MrAl]

Hi again folks,

Pablo:
With these filter caps a small difference doesnt make much difference,
like 470uf instead of 500uf. Samples online? Gee good question,
i dont know but maybe someone else does?

Crux:
Thanks for the suggestion and i'll keep this in mind.

Vic:
Yes final almost
You can throw the linear part together and see how it works alone.

It's possible to increase the fine pot to 500 ohms if you increase all the
other resistors by 5x too, like 1k pot to 5k, 2.7k to (approx) 5*2.7k,
trimpot 5 times original, and 47 ohms to 250 (or closest standard).

It's possible to have a voltage trimmer (to adjust to 0.000v output
for both pots adj'd fully ccw, but it will take another op amp section
and one resistor and one trimpot. If you'd like this it's easy to add so
no prob.

I'd be glad to add some notes about the working of the voltage and current
control...i'll get back with another post possibly a little later or tomorrow.

About the cap: Pablo was looking for a 500uf cap and couldnt find one of
that exact value so i suggested a 470uf cap and changed the schematic too.
Usually i work with nice round numbers (like 500) and then later adjust
the schematic to show the real life obtainable values.

Take care, and Happy Halloween!
Al

 

[vicbin]

Hi Al,

Thanks ! Since you already got this far, why not just add the adjustment for voltage ! /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/popcorn.gif

Will post the result on once I tested it.


Hi Pablo,

Well, if you still insisted on getting 500uF, you can parallel 470uF + 22uF + 10uF = 502 uF , that is quite close though ! he...he... /ubbthreads/images/graemlins/grin.gif

Regards,
Vic

 

[MrAl]

Hi Vic,

Yes, i agree. I little more circuit wont hurt

No need to go through all that cap paralleling (hee hee)
as 470uf is good enough

Take care,
Al

 

[MrAl]

Hi again,

Here's the latest schematic...
This one has a meter amplifier to allow reading 1.000 volts
for 1.000 amps output.
Note that the trim pots MUST be adjusted BEFORE installing
to prevent problems.
Also, when adjusting the pots dont adjust all the way to
either end. This saves on parts.

Here's a brief explanation of the voltage and current
control...

Voltage contol...

IC6 pins 1,2,3 form a 2x amp which makes 2.4 volts from
the ref diode VR1. The pot allows adjusting this voltage
to make up for problems with the two voltage adjust pots
(R3 and R16) which dont allow them to go to 0 ohms, and
make up for a mismatch between R4 and R17.

The IC5 pins 5,6,7 form a adder/subtractor which
adds the voltage across the 0.1 ohm sense resistor and subtracts
two times the voltage across the upper 1.2v ref diode. It can do
this because the non inverting gain is 1 and the inverting gain
is -1. This puts the voltage at pin 7 equal to: 0.1*i-2.4

With no current output (0v out), v7 equals -2.4v, and
with the two voltage adj pots adjusted fully ccw
the two 100 ohm resistors (one at pin 7 and R4) divide
this down to -1.2v at the ADJ pin of IC2, which provides the
0v output.
When there is current flowing, this current times
0.1 adds to the -2.4v signal which adds to the bottom
of the voltage adjustment resistances (R3, R16, R17) to
raise the output level to an amount equal to the amount
across the sense resistor. This keeps the output between
Vout and the left side of the sense resistor constant with
load. This method is pretty accurate and should provide
tracking to within about 2mv with load. There will be more
drop in the external leads than that. This works to 5 amps
too.

Current control...

The heart of this is the secton of IC5 pins 1,2,3.
All this does is compare the voltage across the sense resistor
(which is 0.1v per amp) to the adjusted voltage at the wiper of
the 1k pot. When the voltage gets above the wiper setting the
op amp output starts ramping up from V- until the base of
Q3 (through the 10k) is driven high enough to
cause conduction collector to emitter. This
occurs pretty fast (fast op amp slew rate) and once this transistor
conducts it starts to pull the bottom of R4 down toward about
-3 volts or so. This causes the output to drop, which lowers
the current, hence the current limiting.
The setting is quite accurate, so that once set, the power
supply can function as a precision current source.
The trim pot is there to allow adjusting for 0.000 amps out
when both current set points (coarse and fine) are set fully
ccw. This is needed in case the offset of the LF412A (which can
be about 1mv) is such that it wont allow adjusting
to zero output. Without this trim, the output might still go
as low as 30ma, which isnt bad, and will elminate R12, R11, and VR2,
if R10 pot bottom is connected to ground. This is of course an option
for saving parts for those who dont require adjusting to exactly
0.000 amps output.
Also interesting is that if the trim pot is replaced with a 3.3k
resistor (as shown on schematic) it will allow adjusting down
to 0.000 amps but may go down slightly negative, which doesnt
hurt either in most cases. The 47 ohm and second LM385 is still
required for this however.

Hope this helps.

Take care,
Al

 

[PEU]

Hi Al,

Since the design is close to final, can we do a critical parts list?

Why I ask?

I have a friend coming from USA nov/18 and since some parts are difficult to find here, I can order them from digikey, I mean, 1% resistors, trimpots, multiturn pots, etc. I may even order many values for 1% just in case. What do you think Al?

The others I already have for free /ubbthreads/images/graemlins/smile.gif


Pablo

 

[vicbin]

Hi Al,

Many thanks for the notes, its much-much more clearer now !!

Again, other noob questions (I hope you're not getting tired and bored of my questions) : /ubbthreads/images/graemlins/blush.gif

- Does the voltage loop stability depend "ONLY" at the reference diode (VR1) ? What happened if there is a drift at the LM317/350/338 internal reference (1.25V) ?

- Any reason why R18 to R21 values are 4.99K for the voltage adder/subtractor IC5 opamp ?

- As you said, if both trimmers (volt&current) value change to 500Ohm, just multiply the whole series of voltage divider by 5, please verify if these list of resistors are correct:

Current loop :
R8=2.7K -> 13.5K
R9(coarse pot)=1K -> 5K
R10(fine pot)=100 -> 500

Voltage loop :
R4=100 -> 500
R3(coarse pot)=2K -> 10K
R16(fine pot)=100 -> 500
R17=100 -> 500

Did I miss other components ? I hope this changes won't affect/compromise your design quality, if so, forget it, I'll try harder to find it.

For other readers, please continue with the proposed value by Al, it is just my problem in finding lower than 500 Ohm potentiometer locally, no problem for trimpot though.

- Any chance for a CCM indicator /ubbthreads/images/graemlins/drool.gif , please ? /ubbthreads/images/graemlins/bowdown.gif

Regards,
Vic

 

[PEU]

Hi,

Just finished redrawing the schematics into expressPCB program. This is the 1st step into making a PCB board, please check it for errors:

Schematics Image

Power Supply Schematic file for ExpressPCB

ExpressPCB program (free)

/ubbthreads/images/graemlins/popcorn.gif

Pablo

 

[MrAl]

Hello again,

Pablo:
Ok, i guess it's time to start on a parts list.
Wow, nice drawing. How'd you do that drawing?
Note that the LM385's have a "1.2" suffix.
This is important because they have other types.


Vic:
I dont mind questions as long as i have answers for them /ubbthreads/images/graemlins/smile.gif

If the LM317/x/x internal reference shifts, that's life. It's
supposed to be pretty good however, so i dont think that's much
of a concern. Why did you see something somewhere that may have
suggested the reference would shift a lot?
One of the things about that regulator is the drift is much better
than other three terminal regulators, but let me know ASAP if you
find out any possible problem here.

R18+ should be 1% values to insure that they are all the same.
An error in one or more values relative to another could cause
the output current with load to track incorrectly (ie 5.000v with
no load, 4.980v with 1 amp load). Im hoping 1 percent is good
enough.

Im sorry but you cant change the voltage loop resistor values.
You can still use a 500 ohm pot for the fine adjustment if you dont
change any other values, but it just wont be quite as fine. It may
help to parallel a 470 ohm resistor with the 500 ohm pot, you can try
that.

Yes, a CCM indicator sounds like a good idea. I'll add that right
away. Let me see if i can get back with a new schem a little later.

UPDATE

Im going back to the LF412 instead of the LF412A, because
the 'A' suffix part cost $5.00 each!!! on digikey!!!
The other one is $1.00, better /ubbthreads/images/graemlins/smile.gif

Take care,
Al

 

[PEU]

I did the drawing with the ExpressPCB Schematic program (the link above).

The drawing process is not as simple as microcap, but when you have it, then doing the PCB is very simple, I liked the fact that you can draw a component if missing or redraw an existing one so the pin layour helps drawing the schematic.

Al, as soon you give me the OK on the drawing I'll start with the PCB.

I modified the schematic, because it was drawn using a wrong LM385, now the links above are updated.

/ubbthreads/images/graemlins/popcorn.gif

Pablo

 

[vicbin]

Hi Pablo,

Thank you, that is very nice ! /ubbthreads/images/graemlins/smile.gif

What size of board you're planning ? Is it in one piece for all components or separate board for linear and switcher part ?



Hi Al,

Thank you Sensei, for your patience and leniency with this humble, slow brain apprentice ! /ubbthreads/images/graemlins/smile.gif ..he..he..

[ QUOTE ]

If the LM317/x/x internal reference shifts, that's life. It's supposed to be pretty good however, so i dont think that's much of a concern. Why did you see something somewhere that may have suggested the reference would shift a lot?

One of the things about that regulator is the drift is much better than other three terminal regulators, but let me know ASAP if you find out any possible problem here.

[/ QUOTE ]

Ok Al, if you say it is good, then it is best for me ! /ubbthreads/images/graemlins/grin.gif
The reason I asked is in the past when I was toying with 5mm LED with constant voltage (not CC and it was on purpose) with LM317, the monitored current through the LED was increase when the regulator dissipates amount of heat. But I didn't keep the information.
Looking at the LM317 datasheet, the reference stability against junction temp is quite good right ? Maybe it is nothing as you said, forget it.

[ QUOTE ]

R18+ should be 1% values to insure that they are all the same.
An error in one or more values relative to another could cause the output current with load to track incorrectly (ie 5.000v with no load, 4.980v with 1 amp load). Im hoping 1 percent is good enough.

[/ QUOTE ]

So for 3 Amp setting, are those resistors still at 4.99K ?

[ QUOTE ]

Im sorry but you cant change the voltage loop resistor values. You can still use a 500 ohm pot for the fine adjustment if you dont change any other values, but it just wont be quite as fine. It may help to parallel a 470 ohm resistor with the 500 ohm pot, you can try that.

[/ QUOTE ]

Ok, no problem, actually I did some shopping few days back and still no luck and the only one available is 10 turns Bourne pot which cost approx. $10 ! Will see how is the perfomace using your suggestion first then decide on it ! /ubbthreads/images/graemlins/smile.gif

[ QUOTE ]
Im going back to the LF412 instead of the LF412A, because the 'A' suffix part cost $5.00 each!!! on digikey!!!
The other one is $1.00, better /ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]

Ouch, what a margin !! /ubbthreads/images/graemlins/eek.gif

Look ! What I got for 1 buck for those 5 LF412s ! /ubbthreads/images/graemlins/grin.gif

5 x 1.2 Volts VRs are ready and also 3 schottky diodes (2 X 45V/16A and 45V/10A) ! /ubbthreads/images/graemlins/smile.gif

That ICL7135 is for 4.5 digits voltmeter since you said for current the resolution is capable mA accuracy, 3.5 digits voltmeter won't cut it !

<font color="grey">pssssssst... Pablo, I hope your friend in FL still got a chance for carrying this new one ? /ubbthreads/images/graemlins/grin.gif </font>

Some other "small" things I bought on that day ! /ubbthreads/images/graemlins/grin.gif

Also found some new toy...err..... I mean new species of toroid !! man......I think I'm suffering an "IC" disease (IC=Inductor Cores) ! /ubbthreads/images/graemlins/crackup.gif
Planning to play with them in our switcher circuit ! /ubbthreads/images/graemlins/smile.gif

Regards,
Vic

 

[MrAl]

Hello again,

Pablo:
I've been fine tuning some circuit values but i think
everythings been done now. I'm just ready to start
on the full parts list. Give me another day or so ok?

Vic:
hee hee.
Yes, the 4.99k resistors are for all versions. Im glad
we dont have to change every resistor for the different
versions.
BTW, i added the LED and i'll have the drawing up later or
tomorrow morning.
Guess what? i cant find the darn 100 ohm pot for less than
something like $6.00 !!! That's not good. Now i know
why those big power supplyes are $150.00 and up...those
darn pots are so expensive !!! hee hee.

WOW!! All those nice parts for 1$ ??? Wow, that's really
good and you're lucky you can find them for that price.
I'd like to be able to order from your supplier too!! /ubbthreads/images/graemlins/smile.gif
Nice toroids too! Looks like you're all set for making many
inductors right?

Oh, i forgot i was going to add notes for 5 amp version.
That's next.

Take care for now,
Al

 

[PEU]

Vic, I plan to do a single board PCB because that suits me the best, but I can do a 2 part board if you tell me the split points for sure.

Where do you source parts??? these are reaaaally inexpensive, I can pay here $1 for just a LF412CN or $12 for a LF412MH, may be you can buy for us the parts even with shipping is less expensive than digikey, I can sed the money via paypal.

You can check the prices I expect to pay in these sites: www.electrocomponentes.com.ar or www.elko.com.ar

<font color="666666"> The ICL7135 sells here for about $3, the samples I ordered from maxim still aren't shipped, at the moment I "only" have 2 sample orders from National, plus one on the way that I guess will arrive on time, and a nice sample batch from Onsemi, they charge $11 for overnight delivery, but you can order A LOT of samples look:

SAMPLE 25 16792503 2N3773
SAMPLE 25 16792503 2N6509
SAMPLE 25 16792503 MMBT489LT1
SAMPLE 25 16792503 SS24T3
SAMPLE 5 16792503 MC33063ADR2
SAMPLE 5 16792503 MC34063AP1
SAMPLE 5 16792503 MC33063AVP
SAMPLE 5 16792503 MC34063ADR2
SAMPLE 5 16792503 NCV33063AVDR2
SAMPLE 5 16792503 NCV33063AVDR2G

(all those 33063/34063 are for building flashlight prototypes)

The value of just the 25x 2n3773 to3 transistors is more than $11

Off topic, but I also have some liIon cells from foursevens and some board/lenses/LS from lambda waiting there too

</font>

Al, no problem take your time /ubbthreads/images/graemlins/popcorn.gif


Pablo

 

[PEU]

Vic, how much do you paid for the 1000uFx100 caps?

Best price here is around $0.8 for 1000x63 or $1.40 1000x100
Also found $3.8 for 5000x70

do you have a link of your provider?

And BTW, why did you choosed 100v instead of 63v for the caps rating?


Pablo

 

[vicbin]

Hi Al,

Yippee....CC indicator ! /ubbthreads/images/graemlins/clap.gif

[ QUOTE ]

Guess what? I cant find the darn 100 ohm pot for less than something like $6.00 !!! That's not good. Now i know why those big power supplyes are $150.00 and up...those darn pots are so expensive !

[/ QUOTE ]

If the final result is good, I'm thinking to skip the coarse and fine pot and choose to use the expensive 10 turns pot instead. It should be "adequate" for fine dialing right ? /ubbthreads/images/graemlins/smile.gif

$1 only for 5 LF412, not include those VRs, diodes and the AD chip ! C'mon, if all them cost $1, they're really dirts ! /ubbthreads/images/graemlins/icon15.gif ..he..he..

Too bad, because of the timing, I was hoping can pack some of those opamps & some new cores to you too. Btw, did you receive those "atomic bomb detonators"...err...cores ? he..he... /ubbthreads/images/graemlins/grin.gif

My suppliers are like traditional shops, sort of like Tokyo's Akihabara district with many-many small shops. There is no luxury of online shopping like Digikey here ! /ubbthreads/images/graemlins/frown.gif
This kind of districts are common in the Asia region, and you can find this kind of electronic geek shopping districts ( GEEK ? Sorry, may its just me ! /ubbthreads/images/graemlins/smile.gif ) in every big cities like Hongkong.. and etc. For these shops, the electronic components actually are fast moving goods and sometimes to speed their cash flow they're selling stuffs for a very low margin. I believe the reason why some stuffs are so cheap is because nowdays most of electronic components were made in Asia region.

These pics are not mine, I just randomly grabbed from google since they looks almost the same here.

I had to visit lot of these shops to find the stuffs so there is no one stop shopping shop here, and most of the time it needs a lot of bargaining "from shop to shop" like hunting. Sure it needs a lot of walks & time, but sometime I could get a very good bargain. For example those 3 schottky diodes above, the shopkeeper was so nice that he allowed me to select from a pile of them and he even borrowed me their DMM for me to hunt down the lowest forward voltage diodes ! Spent almost 30 minutes just to buy 3 diodes, not bad eh ? he..he.. /ubbthreads/images/graemlins/grin.gif And the other fun parts was I can watch a lot of weird/exotic stuffs, hard to find or "ancient" electronic components. Remember I told you about tyre sized toroid ? /ubbthreads/images/graemlins/eek.gif

The constraint is time + energy, since they're closed at weekend, I need to take one full day off just to shop even for few components. /ubbthreads/images/graemlins/frown.gif


Hi Pablo, /ubbthreads/images/graemlins/smile.gif

I'm planning to split them into 3 pieces rectifier+powercaps, switcher part and linear part. I think I will design the PCB myself since the rectifier+powercaps and the linear part are already 5 Amps ready. plan to implement 3 Amp switcher first and then move on to 5 Amps.

Thank you very much, really appreciate your offering ! /ubbthreads/images/graemlins/smile.gif

I'm not really planning to re-sell components since those shopping activities are very time consuming. I could help though but shipping cost is a bit expensive and I'm worry it will not justified. /ubbthreads/images/graemlins/frown.gif

A bit off topics, I was looking at your "other" project sample list...this is weird and what a coincidence, I also bought 4 MC34063s at that day too ! /ubbthreads/images/graemlins/ooo.gif

Do you mind share what are you working on with those 1.5A switcher ICs ? also some huge TO3 power transistors ? planning to power thousands of LEDs ? /ubbthreads/images/graemlins/grin.gif
Plan to use them in my car for simple small sized buck converter for LSs and other project.

It is nice that your country has an online shops, but the price a bit steep, don't you think ?

Now, price per piece I've got so far :

LF412CN : $0.2
LM385-1.2 : $0.8 (wrong shop ?) /ubbthreads/images/graemlins/thinking.gif
ICL7135 : $2.9 (need to improve my bargaining skill ?) /ubbthreads/images/graemlins/grin.gif ..he..he..
MBR1045/MBR1645 : $1.5 (with the luxury of choosing the best one/lowest VF, will maintain that good relationship) /ubbthreads/images/graemlins/naughty.gif
1000uF/100V : $0.9 (abit less than yours)
470uF/100V : $0.3
MC34063A : $0.25

The reason why I choose 100V instead of lower one is these caps are just ordinary cap and their ESR is higher compared to specialized low ESR cap for switching circuits. And it is known fact that the higher the voltage rating, the lower their ESR.

If there is no space limitation or other concerns like short switching power path on PCB, we can even use the 1000V one ! The higher the merrier ! Minimal voltage rating at least for the switcher Cin should be 63 Volt if you plan to use the 0-30V type.

The low ESR cap price is "alot more" expensive and for higher voltage rating like 50V, it is even worst. /ubbthreads/images/graemlins/frown.gif

For example, why 1000uF X 6 is better instead of 3300uF X 2 ? By paralleling more smaller caps are better than fewer caps with equal capacity (assuming same v rating), since they will have lower ESR and higher RMS rating "plus" better heat disspations too (larger skin surface) when the switcher on high load.
Cap temperature can increased by itself and if they're in a prolonged warm/hot environment, it will shorten their life span because of drying electrolyte inside them.

Again, I'm no expert, this is what I've learned through the switching literature, CPF and our sensei Mr.Al ! /ubbthreads/images/graemlins/smile.gif

Regards,
Vic

 

[MrAl]

Hi again,

Pablo:
Cant edit the page on the web site to post the latest
schematic. Is something wrong with the site?

Vic:
Oh ok i understand the pricing now.
Geeze, all those shops sell electronic parts? wow?
I wanted to post the latest schematic but the site is
not working or something so Pablo will have to look into
this.

Almost done with the parts list now too including
1.5 amp, 3 amp, 5 amp, 20v and 30v versions.

Take care,
Al

 

[koala]

I've been following this from PEU's PC power supply, is it too late to join now? /ubbthreads/images/graemlins/grin.gif

If I am not wrong, this variable circuit can supply up to 0-30volts, 0-3amps with a 30vac transformer. Right? Question:
1) How does a 30vac transformer supply 30vdc at 3amps? Or is it limited to 30vdc 1amps?

2)So how do I know when I hit the limit? Is there a over-current trip or it will just blow up(sorry bad joke for MrAl /ubbthreads/images/graemlins/naughty.gif)? /ubbthreads/images/graemlins/grin.gif Fuses maybe?

3)Where is the most appropriate place to fuse? I am guessing before the primary, after the secondary and at the outputs?

4)I remember there's a pictorial essay where a bunch of talking dmm sitting in the bin cursing one another /ubbthreads/images/graemlins/hahaha.gif yes vic it was very funny. So How would I wire one up to monitor the output? The IC6 pin 7 goes out to meter. So if I wire up a dmm to read the outputs, what about the 9v power supply for the DMM? Can I have a LM340T9(9v) regulator connected to steal some power for the dmm? Using 9v batteries for me is just too impractical.

Sorry but you guys are listening to a software programmer who has alot of interest in building a powersupply. You may laugh at me but please correct my mistake.

/ubbthreads/images/graemlins/popcorn.gif
Vince.

 

[PEU]

Solved Al, too many amps in a single page /ubbthreads/images/graemlins/crackup.gif ...nah, just a glitch, a flag file wasn't removed properly.


Pablo

 

[PEU]

Hi Vic,

No I don't have an actual plan for those power transistors, just used them as a "filler". Same with the SCR's but these are the type my lathe uses, and if something blows these SCRs are the 1st ones ... /ubbthreads/images/graemlins/smile.gif
Tried to add power diodes but they weren't readilly available.

The 34063 will be used in Lambda IllPill configuration, I may add a schotky + cap at the output for better results.

We do have a street (3 blocks) with many electronics shops here too, even the online ones have branches in that street, but you cannot mess with the parts... and the prices aren't better than the online ones /ubbthreads/images/graemlins/frown.gif

Good tip on the caps, didn't know that fact.

Regarding the PCB, you should try expressPCB, once you link the schematics to the pcb program, drawing boards is a snap.

BTW, where are you in Asia?


Pablo

 

[koala]

Ok... I just went through the latest schematic.. and things are looking OK for me so far... I need some help on component substitute..

D1,D2,D3,D4 1N5402 200V 3A Rectifier Diode
substitute: 1N5404 400V 3A Rectifier Diode?
http://www.onsemi.com/pub/Collateral/1N5400-D.PDF

D5,D6 1N4003 200V 1A Rectifier Diode
substitute: 1N14004 400V 1A Rectifier Diode?
http://www.onsemi.com/pub/Collateral/1n4001rev5dx.pdf

D7,D8 1N4747A
substitute: 1N4747 20v 1W Zener?

D10 1N5822 40v 3A Schottky Rectifier
substitute: 1N5882TR 40v 3A Scotty Diode?
http://www.onsemi.com/pub/Collateral/1N5820-D.PDF

D11 1N5226 3V3 400mW Zener
substitute: 1N4728 3V3 1W Zener?

IC3 78L15 +15V 100ma Regulator
substitute: 7815/LM340T15 +15v 1A Regulator overkill? /ubbthreads/images/graemlins/buttrock.gif

IC4 79L15 -15v 100ma Regulator
substitute: 7915/LM320T15 -15v 1A Regulator overkill? /ubbthreads/images/graemlins/buttrock.gif

IC5, IC6 LF412A Dual op-amp
substitute: OUT OF STOCK ??? /ubbthreads/images/graemlins/banghead.gif /ubbthreads/images/graemlins/twakfl.gif /ubbthreads/images/graemlins/rant.gif /ubbthreads/images/graemlins/jpshakehead.gif /ubbthreads/images/graemlins/icon23.gif /ubbthreads/images/graemlins/frown.gif

Q1 2N4403 PNP ampliflier
substitute: PNP 2N3906?

Q2,Q3 2N4401 NPN ampliflier
substitute: NPN 2N3904?