How to Make a Hi-Fi 100 Watt Amplifier Circuit Using 2N3055 Transistors

The amplifier circuit explained here was built and tested by me and am extremely pleased by its performance and also ruggedness as far as maintenance and handling is concerned.
Basically, the entire configuration is a symmetrical class A amplifier incorporating an input filter stage, an intermediate driver stage and a powerful symmetrical output stage consisting of the versatile 2N3055 power transistors. The circuit efficiently drives a 100 watt 4 Ohms speaker with inputs derived from any audio source like a cell phone or DVD player etc.
Before you learn how to build this interesting and useful 100 watt amplifier circuit using 2N3055 transistors, a prior understanding of the involved circuit configuration would be very handy, let’s begin the explanation with the following points:

Circuit Description

A quick glance at the given circuit diagram makes us conclude that the output configuration is not symmetrical, since the transistors T15 and T16 are both NPN types.

The input stage of the circuit begins or initiates with a symmetrical differential preamplifier stage consisting of the transistors T1, T2 and T3, T4.

T5 and T6 are positioned as the current sources which are further extended as the driver stage consisting of the transistors T7 and T8.

However a closer inspection tells us that of course the wiring is symmetrical, having the transistors T11, T13, T15 at the upper section acting like special booster transistor package.

Similarly the lower section also employs identical super booster stage consisting of the transistors T12, T14 and T16.

The above two sections are perfectly complementary to each other, with reference to the diagram which indicates their emitters being terminated to a common point through the resistors R25 to R27 and via R28 to R30, this effectively that the wiring is exclusively symmetrical by nature.

The output stage is able to produce a massive 200,000 times amplification factor with comparatively very low quiescent current drain.

The quiescent can be set by the adjusting the preset P1.

Due to a non critical nature of the circuit, the entire project can be easily built over a general purpose PCB, however the layout of the components or rather the placement and the ratio of the distance of the components must be kept as identical as possible to the layout of the circuit diagram.

Though a common heatsink may be used for the entire set of the output devices, I personally used separate individual heatsinks for each of the transistors. This saved me from the headache of using the cumbersome and low efficient mica isolation kit between the transistors.

The inductor is kept for improving the dynamic nature of the circuit. It is built by winding 20 turns of super enameled copper wire over the 1 Ohms resistor itself. The wire is selected to be close to 1mm in thickness.

Though not absolutely necessary, for better thermal stability the transistors T9 and T11 and also T10 and T12 should be glued together, preferably by attaching the respective pairs face to face.

The quiescent current should be ideally set to 50 mA through the following initial procedure:
Short the speaker terminals,

Connect a DMM set at current range in series with the positive of the power supply to the circuit,

Next adjust the preset such that the meter reads an input of 50mA, that’s all, the amplifier’s quiescent current is set and now the connections may be restored for the normal operations of the system.

The power supply circuit is also shown along side and as can be seen there’s nothing special about it and may be built using the shown ordinary sets of components.




Parts List of 100 watt amplifier circuit


R1 = 430 K,
R2 = 47K,
R3 = 330 Ohms,
R4, R5 = 12 K ,
R6, R7, R20, R21, R22, R23, R24 = 1 Ohm, 3 Watt, Wire Wound Type
R8, R17 = 68 Ohms,
R9 = 100 K,
R10, R11, R12, R13 = 5K6,
R14, R15 = 12 K,
R16, R19 = 100 Ohms,
R25 = 10 Ohms / 2 Watts,
P1 = 100 Ohms Preset, Linear
C1 = 1 µF / 25V,
C2 = 1 n, CERAMIC,
C3, C4 = 100Pf
C5 = 100 n,
C6, C7 = 1000 uF / 35 V,
L1 = 20 turns of enameled 1mm copper wire over R24,
D1, D2 = RED LED 5mm,
All other diodes are = 1N4148,
T1 = Matching BC546 pair,
T2 = Matching BC556 pair,
T3 = BC 557B,
T4, T7, T8 = BC 547B,
T5, T12 = BC 556B,
T6, T9 = BC 546B,
T10 = BD 140  
T13 = BD 139  
T11, T14 = 2N 3055  
General Purpose PCB,
All the transistors T10, T13, T11 and T14 ae mounted on suitable heatsinks



The original design, (courtesy - elektor electronics)






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177 comments

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Anonymous
August 15, 2012 at 1:36 PM delete

I know this circuit. Its crescendo... the best ever i had in my life. Mine is working fine...12 years now. no error at all. The driver BD139/140 can be replaced by C2073 and A940.

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October 3, 2012 at 9:57 AM delete

PLZ TELL THE SPEAKER RATINGS LIKE 8 OHMS/1WATT OR SOMTHING LIKE THAT PLEAASE ITS URGENT

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October 3, 2012 at 9:59 AM delete

Also please can you show me how to connect the transistor on the PCB. please help i am new to this transistor.. i have a to-3 package which has only 2 legs. the base and the emitter...furthe the collector part is the rest of the metal body.. plz help

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October 3, 2012 at 10:25 AM delete

Speaker must be rated at 4 Ohms/100 watt RMS

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October 3, 2012 at 10:42 AM delete

Please refer to the 2N3055 datasheet for knowing the pin details.

By the way they must be mounted on heatsinks, not on PCB directly.

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Anonymous
November 26, 2012 at 2:16 PM delete

thanks for sharing this interesting looking cirucit. I look forward to maybe trying this out with some 2n3055s. By the way the power supply schematic shows a "dual" or center tap output. But your circuit shcematic has just 25V -GND. What is the correct voltage ... +25 GND -25 or +25 - GND ?

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November 26, 2012 at 2:38 PM delete

You are welcome.....one of the terminals of R1,R2,C2,C6,C7 are connected to ground point, or the (0) point of the power supply.

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Anonymous
December 1, 2012 at 10:33 PM delete

supply. 32-0-32 5A. that is the best, T10 T11 T13 and T13 are directely exposed to 5A. The rest of the circuit, supply can be given through two diodes IN 4007. It will deliver only 1A max. That good for small transistors so as to keep distortion minimum as possible. U can give voltage from 27-0-27 to 34-0-34 max.

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Anonymous
December 1, 2012 at 10:37 PM delete

This circuit gives 45W into 8 ohms and 65W into 4 ohms. The sound quality is superb.

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Anonymous
December 1, 2012 at 10:41 PM delete

In actual crescendo circuit, The instead of LED D1, there is 5.6V zener and 47uf capacitor connected in parallel. Same as in the other side D2 also. Why there is a LED here ? Is it for thermal stability ?

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December 2, 2012 at 8:38 AM delete

LED is used for eliminating noise which is normally a problem with the zeners.

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Anonymous
December 13, 2012 at 8:05 PM delete

TDA1557Q is mosfet amplified duel amplifier 100 + 100 Watt IC... :)

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December 14, 2012 at 9:15 AM delete

:-O :-) :-D Thanks very much.....

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Anonymous
December 30, 2012 at 2:09 PM delete

Fine, every one is running after the amplifier power output rather than the quality of sound. The sound produced from these types of crescendo circuit is better than you hear from theater.

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Anonymous
January 3, 2013 at 5:52 PM delete

@ power supply circuit.... what should be the rating of the transformer? And what type those diodes connected in full bridge in the power supply circuit?

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January 3, 2013 at 9:30 PM delete

The details are provided in the diagram.

Diodes can be 1N5408s

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Anonymous
March 7, 2013 at 10:34 AM delete

I have a few questions and I hope someone can help me with these. I am building this circuit and in the Circuit Description Column it mentions the R25 to R27 and via R28 to R30. I see R25 but not R26 to R30 or am I missing something?
The resistor between T8 and T7, what number resistor is it and the value?
Then I see R18 in the drawing but not on the parts list, what is the value to R18.

I appreciate the help,
Thank,
Tony

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March 7, 2013 at 2:48 PM delete

please check out the updated (original) circuit in the article

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Anonymous
March 7, 2013 at 6:40 PM delete

Thank you Swagatam. Now with the original do I use the components values from that or do I have to redo the whole circuit to the original schematic.
And thank you for your quick response.

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March 8, 2013 at 8:14 AM delete

I think there's hardly any difference between the diagrams, you may continue with the previous components.

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Anonymous
March 16, 2013 at 10:42 PM delete

Thats it ... thats the crescendo baby. This circuit was famous in 90s. I still have the picture of printed PCB softcopy with me. This PCB was last produced by HITECH company, now they stopped producing electronics goods. Thats made the end of this PCB board. No one can reprint the board without permission. Then people are forced to relay on other circuits. The beauty is, this is a marvelous design and can handle low frequency (low bass) without any problem. Almost no other modern circuits can beat the flat frequency response delivered by this amplifier. The only thing is You should give 28-32V dual supply, 4A-5A current for superb low bass effect.
The very first crescendo circuit is published in elektor magazine on December 1982 :-)

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Anonymous
June 7, 2013 at 10:42 PM delete

Hi, everybody. yes, it is a great amplifier. I tried it on a veroboard but hum is too much. anonymous says he has the PCB soft copy. will you pls email it to nkanil.klm@gmail.com?
Anilkumar

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Anonymous
June 23, 2013 at 10:46 PM delete

I have posted the circuit dude.
Lancy Felix.

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July 28, 2013 at 2:59 PM delete

Sir,
I want to made this audio amplifier circuit. But in the amplifier circuit you show the 25V supply and in power supply circuit there is 30V.
What is co-relation between them. secondly, I want to known the rating of center tap transformer you have used.

Sudesh

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July 29, 2013 at 9:54 AM delete

After rectification the voltage may rise upto 30V, but it won't be a problem because the amplifier can handle upto 40V

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Anonymous
September 4, 2013 at 10:06 PM delete

Hi Anonymous can u please sent me the pcb soft copy of the amplifier. My mail id patnaik2surya@gmail.com. thanks in advance.

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Anonymous
September 10, 2013 at 8:07 PM delete

I had posted the amp PCB diagram ( with both sides) dude. Use photoshop, make more darker circuit and print in on copper clad glass epoxy board :-)
Anyway this amplifier got a special powers supply board with an input 27-0-27 and 18-0-18 AC and the output is 27-0-27, 18-0-18, +-24 and +-12v DC supply (This is for tape deck, transistor pre-amp, tone control etc.. I have the same amp + powersupply board on my old deck and powersupply board contains transistors like BD139, BD140 etc.. i dont want to reverse engineerer that stuff.... The above power supply circuit is ok for the main amplifier as told by 'Swagatam Majumdar' but actually 4700ufx4Nos capacitor is there in actual board....
Finally my name is Lancy Felix :-)

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September 11, 2013 at 10:25 AM delete

Thanks for the help Lancy, keep it up mate:)

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Anonymous
September 11, 2013 at 1:42 PM delete

Hi Lancy, will you please send me those PCB designs? My email is
wedt400@gmail.com .Thank you.

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September 17, 2013 at 10:37 PM delete

do you have any sub woofer pre amplifier circuit for this power amp if you have mean's wiil you please send me (kanagarajbe114@gmail.com)

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September 18, 2013 at 1:19 PM delete

You can use the following circuit, just add a low pass filter at the input of the amp:

http://homemadecircuitsandschematics.blogspot.in/2012/04/how-to-make-simplest-100-watt-mosfet.html

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September 19, 2013 at 8:59 PM delete

Thank you sir,and i want single supply transistor power amplifier circuit I have o-24 transformer 5amps

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September 20, 2013 at 5:54 PM delete

I am sorry kanagaraj, I do not have any such circuit presently in my blog, I will try to update it if possible soon.

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September 20, 2013 at 9:40 PM delete

sir hoe to increase left right bass depth without using tone controles (only using pre amplifier) if you have any circuit like that give me

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September 21, 2013 at 12:17 PM delete

You can replace the preamplifier with this circuit, it will work as both preamp and low pass filter:

http://homemadecircuitsandschematics.blogspot.in/2013/06/make-this-low-pass-filter-circuit-for.html

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September 24, 2013 at 7:41 AM delete

sir i want one automatic battery charging circuit (12v) i want that circuit automatically sence low battery and start charging and cut the charging when the battery is full

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September 24, 2013 at 7:41 PM delete

Hi Kanagaraj, You can make this circuit:

http://homemadecircuitsandschematics.blogspot.in/2012/02/how-to-build-automatic-6-volt-12-volt.html

replace the feedback 1K resistor with 100k pot and remove the series 1N4148 diode.

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September 28, 2013 at 10:41 PM delete

sir hoe to cut below 80HZ in low pass filter circuit

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September 29, 2013 at 7:32 PM delete

By carefully adjusting the 22k presets.

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October 5, 2013 at 7:00 AM delete

sir i want buffercircuit & bass boost circuit using op amp

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October 11, 2013 at 10:23 AM delete

what is the different between digital ground and analog ground and how to joint these two grounds

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October 11, 2013 at 5:24 PM delete

it's a big explanation, cannot provide it here....these grounds are intended for providing discrete paths for analogue and digital signals, they should not be joined.

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Anonymous
October 20, 2013 at 5:49 PM delete

Hi everyone!
Would somebody send me a PCB design of Crescendo Amp from the shematic up there..Will be very grateful :-)
My email; linjo456@gmail.com
Thank you !

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Anonymous
October 21, 2013 at 4:15 PM delete

Hi sir, can you send PCB soft copy to my mail:- k.amit2000@gmail.com

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Anonymous
October 28, 2013 at 6:12 PM delete

Sir,
I have built this circuit and its working nice . Thanx for the circuit .
I am connecting this amp to woofer and tweeter so how I should connect them by creating passive crossover . What values of capacitor and inductor should be used ?? What kind of Inductor to be used ??

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October 28, 2013 at 9:25 PM delete

Don't use passive filters, use active filters as it will enhance the effects rather than deteriorating.

You can use the circuit IC2A/B section of the circuit shown in this link, use it in between your amp and music input:

http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-your-own-active.html

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Anonymous
October 28, 2013 at 11:35 PM delete

Sorry for the delay yar. I have forwarded the PCB diagrams . Anyway am using passive filter only for the above amplifier. Mine is BOLTON, model no 305 BN2. Its some what old but very simple construction and awesome filter. Its good choice to wind coils rather than buying. The modern multiple coil crossover is worth useless. Just open any old 10" or 12" audio box, (70's to 90's is good... Old is Gold) measure the coil gauge, ID, OD, and height of that wound core, no:of coil in a single layer. Perimeter =Pi*D. You could easily calculate the total coil length. The only important thing is coil thickness.. the more the better. You could recalculate with simple equation also.
Otherwise measure with wire gauge, measure the inductance... done :-)
Lancy Felix.

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October 29, 2013 at 10:15 AM delete

That's great support Lancy, Thanks very much.

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November 6, 2013 at 6:53 PM delete

Hi Anonymous, could you please send me the PCB layout for this "Crescendo" amplifier. My email is agungprie2010@gmail.com.
THank you in advance..

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November 8, 2013 at 7:33 AM delete

hi Anonymous,could you please send me one regulated power supply circuit with output short circuit protection(12V/3A)

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November 24, 2013 at 5:52 PM delete

Would it be okay if i use all the smd component instead of through hole component ,can my circuit behave diffrently under smd components ????

Please answer ......

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November 25, 2013 at 7:46 PM delete

yes you can use SMD, the circuit will work perfectly with them too, no issues.

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December 10, 2013 at 10:39 PM delete

there are 2 types of 3055 transistor. first one is 2N3055 and other one is TIP3055. TIP3055 is a big transistor. 2N3055 is like a normal transistor. which one is good for this amplifier. I cant understand the L1 . How can i make it in home. I'm stuck in this plese reply me soon.

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December 10, 2013 at 10:59 PM delete

can you post a completed circuit with all parts

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December 10, 2013 at 11:14 PM delete

can you send PCB soft copy to my mail:- manujamicro1@gmail.com

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December 10, 2013 at 11:17 PM delete

please some one send me the PCB soft copy. my email- manujamicro1@gmail.com

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December 11, 2013 at 10:05 AM delete

The value of L1 has been updated in the parts list.

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December 11, 2013 at 10:57 AM delete

Both the transistor types are almost identical with their specifications, only the package is different.

You can use any of these as per your convenience....I have updated L1 data in the parts list.

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December 12, 2013 at 8:17 PM delete

http://i00.i.aliimg.com/photo/v0/309836240/TIP3055_Power_NPN_Transistors_ST.jpg

http://img.bhs4.com/fa/d/fadf150f65b8acbacfb586f7ab802d0a80dced83_large.jpg

checkout this links and tell me the witch transistor is good for this circuit. please some one send me the PCB soft copy. upload that and give me the download link.

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December 12, 2013 at 8:18 PM delete

is there a good quality bass in this amplifire.

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December 13, 2013 at 10:55 AM delete

as mentioned in my previous comment, both the transistors are good and rated almost equally, it depends which one you prefer as per your convenience.

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December 13, 2013 at 8:10 PM delete

http://i00.i.aliimg.com/photo/v0/309836240/TIP3055_Power_NPN_Transistors_ST.jpg

then can I use this transister

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December 14, 2013 at 10:34 AM delete

yes you can use them, be sure to add large finned heatsinks to them

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December 14, 2013 at 10:35 AM delete

No, it does not include bass control, you will have to add it externally

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December 14, 2013 at 2:34 PM delete

no no I mean the sound. can i get a good bass sound from this

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December 14, 2013 at 2:37 PM delete

do you have is there any subwoofer circuit schematic. if you have please send me. Because i want a good bass. thats what i like

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December 14, 2013 at 2:45 PM delete

in our city there was a young man. he makes subwoofers in home and sell them. but i dont have money to buy that. he has many types of subwoofers. like 5.1 , 2.1 , 7.1. now he is not here. but i want to make one. quality bass sound subwoofer circuit diagram. thats what i need. if you have that send me. i will give my email. thankz

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December 14, 2013 at 8:14 PM delete

you can get god bass only after including a bass/treble circuit at the above amplifier input

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December 14, 2013 at 8:20 PM delete

I'll try to include it soon in this blog and give you the link....

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December 14, 2013 at 8:23 PM delete

presently i do not have it, i'll try to post in soon and let you know.

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December 15, 2013 at 10:31 AM delete

ow do you have above amplifire pcb diagrame?

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December 16, 2013 at 10:59 AM delete

sorry, presently the pcb design is not there with me...

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December 17, 2013 at 12:43 PM delete

I have seen your link, yes you can use it with the above circuit

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December 17, 2013 at 12:51 PM delete

...and please do not include external links, i'll just keep deleting them.

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December 18, 2013 at 8:24 PM delete

how can i contact you for a personal matter immediatly pleaseeeeeeeeeeee

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March 24, 2014 at 4:06 PM delete

This looks like a very nice amplifier, thanks for the detailed schematic and items list! I have just ordered the components and I'm excited to get started!

I have one questin though - I can't seem to figure out the recommended power suppy voltage/current. I'm confused with the shchematic sayin "Tr1, 2 x 25" Do I need a dual transformer, or?

If I only need one, will 30 Volts at 5 Ampere be suficient? Can less do it?
Im planning on winding my own transformer, so no need for "standard values" :)

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March 25, 2014 at 6:51 PM delete

Thank you!
The transformer needs to be a center tap transformer, that is with two sets of winding on the secondary, rated as 24-0-24V at 2amps or more.
you can use a transformer rated at 30-0-30V/2amps also.

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March 30, 2014 at 5:01 AM delete

Thank you very much. If I want to make 2 of these amplifiers, one for each channel, can i just make two identical amps and ground them to the same "0" on the transformer (offcourse with twice the current), or do I need 2 seperate center-tapped windings with their own respective "ground/0"

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March 30, 2014 at 12:58 PM delete

separate power supplies won't be required, you can use the same supply, just by making the grounds common...

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March 30, 2014 at 12:59 PM delete

(+) ans (-) supply lines will also need to be joined as common rails for both the units....

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April 6, 2014 at 5:51 PM delete

So, ff I measure between;
+ & 0 = 25V
- & 0 = 25V
+ & - = 50V

Correct? :)

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April 10, 2014 at 12:45 PM delete

Hi guys, could you please send me the PCB layout for this "Crescendo" amplifier. My email is ttararo@gmail.com.
THank you in advance..

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April 13, 2014 at 2:11 PM delete

hi Lancy Felix

is it possible for you to send me a pcb layout for this amplifier?
my email address is ttararo@gmail.com

much appreciated.

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April 18, 2014 at 11:29 PM delete

Hi again

I have built the amplifier, and i am getting an amplified signal out of the speaker, but it is very quiet, and a bit distorted. I tested the voltage over all the tranistors, and its at approximately 35 volts, except the T7+T8 - they are only showing between 0,1 - 1V. What could I be doing wrong?

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April 19, 2014 at 9:37 AM delete

No, there's definitely something hugely wrong with your connections or the parts.

Once built and set the output should provide a large amplification, even without any input music you should be able to hear a big Hiss on the speaker.

did you adjust the quiescent current as suggested in the article??

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April 19, 2014 at 1:56 PM delete

I adjusted the P1 with an multimeter in series with (+) to the power supply, but no matter how much I djusted the 100Ohms preset, it only showed around 3-5mA

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April 20, 2014 at 9:59 AM delete

there's something not correct in your circuit, check all the connections many times you should be able to locate the fault...I built this circuit some 10 years ago and succeeded at the first attempt.

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April 22, 2014 at 6:38 AM delete

sir i need regulator power supply for luxion 1watt led i want to connect 8 led's input voltage 24v

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April 22, 2014 at 6:01 PM delete

use the following circuit

http://homemadecircuitsandschematics.blogspot.in/2013/06/universal-high-watt-led-current-limiter.html

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April 28, 2014 at 12:24 AM delete

Hi from Athens, could you please send me the PCB layout for this amplifier.
My email is panzac5@gmail.com
Thank you very much

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May 15, 2014 at 8:13 PM delete

can we use MIC 6A4 diode in power supply.

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May 15, 2014 at 8:16 PM delete

Is it possible to convert a existing 2n3055 based amplifier into a mosfet one.

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May 16, 2014 at 3:15 PM delete

will require too many modifications,...

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June 9, 2014 at 9:30 PM delete

HI ANONYMOUS,
I WOULD LIKE TO HAVE SOFT COPY OF 100 WATT(2N3055) AMPLIFIER PCB DESIGN SOFT COPY. MY e-mail ID -kamleshmakim@yahoo.com

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June 10, 2014 at 11:31 PM delete

can we use tip or mje 3055 in place of 2n 3055 and which will be better

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July 26, 2014 at 3:44 PM delete

Hi Swagatam sir

please send me the above pcb diagrams.

my email id: bhudha@gmail.com

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October 10, 2014 at 10:37 PM delete

Good day sir. Could you please send me a copy of the PCB layout. Thank you very much.
evokhyn@gmail.com

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October 11, 2014 at 1:47 PM delete

sorry, PCB layout is not available.......

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October 11, 2014 at 5:39 PM delete

good day sir. I am currently making this circuit. I just have a question. At the bottom left, is there really a connection under R12? I just notice that there was an excessive line going to the left and it is not like the one on the top left. I am just confused because if they are really connected, then the non-connected lines between R14 and R19 are useless. Can you please clarify sir? I will wait for your response to be able to continue the build. Thank you.

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October 11, 2014 at 5:42 PM delete

And I also noticed the power supply circuit. Is the output going to be 25V/5A? Coz I can see a 30V on the bottom left. thank you sir.

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October 11, 2014 at 8:27 PM delete

good day Evo, i can't see any extra line anywhere, R12 and R11 rails seem exactly symmetrical...did you click the image to enlarge?? please click it to enlarge.

R14 and R19 are wide apart, they have no link at all...I hope there's some confusion in reading the diagram from your side...enlarging it will clarify it

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October 11, 2014 at 8:29 PM delete

power supply outputs will be +25 0 -25V dual supply but after rectification it could well become +32 0 -32v

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October 13, 2014 at 7:19 PM delete

this part sir, at the picture. the horizontal line.

http://www.4shared.com/photo/D7dy-2CJba/amplifier-100-watts.html

thank you for the response.

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October 13, 2014 at 8:52 PM delete

Evo, please go with the following diagram, it's the original one and is more correct:

http://4.bp.blogspot.com/-6H3usY45JAM/UThb0mHH85I/AAAAAAAADdU/wNpmxml3ph8/s1600/100+watt+amplifier+circuit.jpg

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October 14, 2014 at 10:35 PM delete

i think the line is an excess sir. thank you very for your help.

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October 15, 2014 at 10:29 AM delete

the extension from R12 ground towards left is a drawing mistake, rest everything is correct in the first diagram.

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October 15, 2014 at 11:40 PM delete

Good day sir. I already decided to make the original version and currently building it. My only concern is that my transformer is only around 21-0-21 and after the rectification it goes up to 28-0-28. It would be good to the new amp design but in the original it indicates around 30 to 35v input. Im a little under voltage. Will this be a problem?

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October 16, 2014 at 11:42 AM delete

Good day evo, there won't be any technical problem if the voltage is decreased, the wattage of the amp will decrease proportionately.... that's all .

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October 16, 2014 at 6:01 PM delete

thank you very much for your help sir.
I would also like to inform you that my classmates had a problem with the new version of the design. the LED on the upper part wont turn on, T13 explodes and C7 is connected on the wrong terminal. The first time they turned it on, C7 exploded. I think its because the positive terminal of the capacitor is connected to the negative of the power supply.
That's why I decided to make the original version. I'll also update as soon as I finish this project. Thank you very much sir Swagatam.

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October 16, 2014 at 9:45 PM delete

One last thing sir, in the original design, there are C3, C4 and C5 connected in parallel with 820nF each. We have a difficulty in resources here so I cant find an 820nF. But when the three are added, they will have a sum of 2.46uF. The nearest capacitance I can buy is 3.3uF. And I have no choice but to change the three capacitors with one 3.3uF. Im just not sure if this is still okay. I apologize sir but I'm new to this. You've been a great help.

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October 17, 2014 at 8:03 AM delete

Evo, the new version is also correct except C7 which needs to be reversed and R12 ground side short, except these two drawing mistakes all seems right in the diagram.

connecting 3 in parallel will have other benefits but you can also try a 3.3uF instead it would do any harm.

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October 17, 2014 at 7:01 PM delete

Good day sir. I used 4 capacitors for the parallel connection with 560nF. their result will be closer to the sum of 3 capacitors of 820nF. I havent tried it yet coz I have a difficulty having the result of 4-6uH for the inductor and my potentiometer broke. thank you for your help sir.

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October 18, 2014 at 10:15 AM delete

Yes it will do...


for the inductor simply wind any moderately thick magnet wire over the resistor itself....wind 20 turns.

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October 18, 2014 at 4:15 PM delete

do you mean i'll put the inductor on top of the resistor? or wrap the resistor? sorry sir coz im a little confused. then connect their legs in parallel. thank you sir. I still have to wait until monday to resume making the amp. thank you very much sir for your non stop help.

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October 18, 2014 at 9:41 PM delete

yes that's right, wind the copper wire directly over the resistor and then solder the leads (resistor and the coil) together across the given PCB holes.

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October 19, 2014 at 12:06 PM delete

Okay sir. Thanks a lot. I'll notify you as soon as the amp is done.

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October 20, 2014 at 6:06 PM delete

Good day sir. We already made the amp but without the inductor first because we didnt have the chance to buy today. We have a little problem. the sound was too low. like there was no amplification. but we used a mono jack to connect to our cellphones. maybe it was the problem. or is it something else? we are so close to finishing this project. is there something we can do? we will try to use a 3 pin stereo jack tomorow and short the left and right. will it be okay? thank you sir.

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October 21, 2014 at 11:14 AM delete

Good day Evo,

do not connect any music at the input just touch it with your finger, it must produce a very loud buzz in the speaker, and a small hisss when the finger touch is removed.....if this is not happening surely there's something terribly wrong with your circuit assembly.

I built the second design in the year 2000 when I was quite new to electronics, yet I succeeded to get the best response from it at the first attempt....i had used a general purpose board...not even a PCB

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October 21, 2014 at 11:15 AM delete

mono or stereo input is not the problem...the problem is surely in the amplifier circuit itself....

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October 21, 2014 at 11:16 AM delete

by the way make sure to set the quiescent current with the help of the given preset in the amp....otherwise the circuit will waste a lot of power unnecessarily.

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October 21, 2014 at 4:26 PM delete

yes sir. i can hear a buzzing sound but not that loud. and i can also hear a little hiss when i turn the amp on. but the sound is not that loud.

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October 21, 2014 at 6:38 PM delete

and can the V+ and ground terminals of the P1 interchangeable?

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October 21, 2014 at 7:41 PM delete

it should be very loud, the vibration on the speaker cone should be very high and visible to eyes...something may be not correctly done or the components may be faulty

check and set quiescent current as explained in the article.

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October 21, 2014 at 8:10 PM delete

presets do not have polarities, just use the center lead and any of the outer leads of the preset for the connections..... anyway round...the other outer lead can be left open or unconnected

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October 21, 2014 at 8:13 PM delete

we are also using 100ohm preset trimmer with the middle pin connected to one of the front pins.

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October 21, 2014 at 9:00 PM delete

and lastly sir, this is the schematic diagram which my classmates used. is this the same?

http://www.brighthubengineering.com/diy-electronics-devices/94189-make-a-100-watt-transistor-amplifier-circuit/

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October 22, 2014 at 8:17 PM delete

sorry sir but im new to potentiometers. should I use the center terminal and one outer terminal?

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October 23, 2014 at 9:31 AM delete

the center lead is the important one, the other one could be any one of the outer two leads.

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October 24, 2014 at 10:51 AM delete

okey sir. thanks a lot. ill notify you for an update.

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dch
December 31, 2014 at 5:10 AM delete


Can I build this without any printed circuit board? Or is printed circuitry required?
It is suggested to stick to diagram layout yet two pairs of transistors are suggested to be glued together. They are in widely different parts of the diagram. How to do this? 'Fold' the circuitry up? Or have long leads to the transistors, putting them above the rest of the circuitry.
This will be a first project ever for me.
:)

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December 31, 2014 at 1:30 PM delete

yes you can do it, because I myself built it on a dot matrix PCB and succeeded in the first attempt...refer to the diagram that's given in the bottom of the article, I think the transistor glueing info may not be correct so don't do it, I'll check and update the correct data soon.

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December 31, 2014 at 1:31 PM delete

OK..the transistor glueing instructions is relevant to the last diagram...I hope you won't have to fold the PCB now:)

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January 2, 2015 at 3:33 PM delete

good day can i use a 18-0-18v, 6amp transformer for this amplifier, thanks

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January 20, 2015 at 9:08 PM delete

Hi, I would like to know if this circuit is used for creating 5.1 channel amp then how many transformer is needed......in other words how do u power this amp

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January 21, 2015 at 9:35 AM delete

Hi, you could use the above circuit along with the following one for getting a proper 5.1 implementation

http://homemadecircuitsandschematics.blogspot.in/2012/08/exploring-ic-tda-7560-4-x-45w-quad.html

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January 21, 2015 at 9:36 AM delete

the amp is powered from the shown power supply design and the signal input is acquired from any music system headphone out

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January 22, 2015 at 12:26 AM delete

Hi thanks for the info,actually my aim is to build a HI-FI 5.1 home theater system (100 watts in each channel if possible) with tweeter + mid range speakers in 4 of the channels and the rest would be center and sub.So pls advise me what circuit would be the best for this....thanks in advance.

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January 22, 2015 at 1:11 PM delete

You can try the following simpler design, it also has been tested by me:

http://homemadecircuitsandschematics.blogspot.in/2012/04/how-to-make-simplest-100-watt-mosfet.html

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May 27, 2015 at 10:39 AM delete

please send me the above pcb diagram at anwar621@gmail.com

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August 22, 2015 at 6:02 PM delete

Hi Khushin Makim, please send me the sof copy of 100 2N3055 PCB. My email id : geotek_co@yahoo.com
Thanking you,
Gautam Kumar Goswami

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August 28, 2015 at 9:08 AM delete

Please Swagatam Sir, Kindly upload corrected diagram for error free and last long daily use of this project.

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August 28, 2015 at 11:38 AM delete

Hi Abinash, who said the diagrams were not correct?...both the diagrams are perfect, however the last one has been tested by me...so you can try that.

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August 28, 2015 at 1:04 PM delete

I am an audio buff. Can you please send me the soft copy of its pcb to geotek_co@yahoo.com ? Please help.

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August 29, 2015 at 11:13 AM delete

Thank you Swagatam Sir, for your quick reply. Please give your email id for share some valuable information with picture about this project. I will expect support like that from you in future also.

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August 29, 2015 at 7:44 PM delete

Abinash, commenting in the my website is the best way to get in touch with me without fail....for image presentation you can submit it to:

admin @ homemade-circuits.com

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August 30, 2015 at 6:17 PM delete

Good Evening Swagatam Sir,
If possible, can you please upload a video in youtube of 2N3055 amplifier you have already made in the year 2000. So we can able to hear sound quality of this Class A amplifier.

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August 31, 2015 at 7:42 AM delete

Good morning Abinash, sorry that won't be possible because it was built and used by me a long time ago, and was later dismantled for some other purpose

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October 7, 2015 at 7:16 PM delete

Is this a 2.1 amplifier? Or just mono?

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October 8, 2015 at 4:32 PM delete

It's a mono amp...you'll need of these to get a stereo output

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November 12, 2015 at 5:33 PM delete

Please send me the PCB diagram. My email is : geotek_co@yahoo.com

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November 12, 2015 at 5:45 PM delete

Dear Mr. Swagatam Majumdar, I want to build this amp & for this I need help from you. One is the PCB in soft. Can you please send it to my email id ? I also need a suitable preamp & tone control unit suitable to its specification. My email id is : geotek_co@yahoo.com

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November 12, 2015 at 7:21 PM delete

Dear Gautam Kumar Goswami, you can find all the details in the following article:

http://www.eeweb.com/project/circuit_projects/300-watt-mosfet-real-hi-fi-power-amplifier

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November 13, 2015 at 1:31 PM delete

Dear Mr. Majumdar, I requested for the output 2 x 2N3055 based 100W amplifier PCB in soft & its current upto dated circuitry. Please help. My email is : geotek_co@yahoo.com. Thanking you in advance,

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November 13, 2015 at 8:37 PM delete

oh..sorry, it's not available with me at the moment...

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November 16, 2015 at 10:45 AM delete

Hi Lancy Felix, my name is Gautam Kumar Goswami & I am a Hi Fi Buff. I want to build this 2N 3055 based 100W power amp. Kindly send the PCB diagram soft copies to my email id : geotek_co@yahoo.com
Thanking you in advance,
G.K.Goswami

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November 28, 2015 at 1:00 PM delete

Hello sir. I am constructing this amplifier. Please send me the pcb layout at telangrajiv@gmail.com
Rajiv

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December 27, 2015 at 7:33 AM delete


good evening beautiful project . it would be possible to have the technical data of the amplifier ? is it possible to have the PCB soft at chri3399beltrami@gmail.com?
thanks christian

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December 28, 2015 at 10:50 AM delete

thanks, you can refer t the following pdf for more details:

http://raylectronics.nl/pdfs/Crescendo_Millennium_en.pdf

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January 14, 2016 at 2:16 PM delete

Please send me the soft copy of the PCB layout to my email: geotek_co@yahoo.com

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lan
January 14, 2016 at 4:24 PM delete

Hi Gautam Kumar Goswami.
Sorry for the delay. PCB softcopy diagrams posted dude. Enjoy.
Lancy Felix.

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January 28, 2016 at 2:44 AM delete

Hi, I saw this circuit a long time ago, but didnt had the time to actually do it, my question , is the schematic good ? ( i read here that the 2nd photo has some drawing mistakes ) and whats the name/model of the Amplifier, i heard it's crescendo. I have a couple of 2n3055 made in 88" ( i think they are better then the new ones ) also , its the 2n3772 " better " or at least can be used instead of the 2n3055 in this circuit ?, Thank you, sir !

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January 28, 2016 at 2:50 AM delete

Hi, can you tell me the brand model of this circuit please ? , thank you

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January 28, 2016 at 10:34 AM delete

Hi Bruno, The circuits are perfect! and will work no matter which one you build.

2n3772 is good, and can be used instead of 2N3055

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March 3, 2016 at 7:58 PM delete

Hi,
could you upload the pcb layout o send it to me to
Thanks

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April 19, 2016 at 10:03 PM delete

I have made this apm on a protoboard...and for the love of God i cant make it work...the input just gose to the speaker with no amplification and the amp draws 2A, i have used the undmodified circut...i have used bc557c and bc447c insted of the b version, is that a problem?Suplly is +-25V

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April 20, 2016 at 9:58 AM delete

BC447 is not the problem unles it's faulty...the circuit is huge and the fault could anywhere in the design.

the quiescent current consumption of the circuit without load should be first set to 50mA

this is done by shorting R1/C1 junction of the amp to ground, speaker connections open, ammeter connected in series with the ground line, and P1 adjusted until the meter reads 50mA

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April 21, 2016 at 7:15 PM delete

i'll try it on a proper PCB, then we'll see if it works..

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