Saturday, January 7, 2012

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)






137 comments:

  1. 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.

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

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    2. will require too many modifications,...

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

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

    ReplyDelete
    Replies
    1. Speaker must be rated at 4 Ohms/100 watt RMS

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

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  3. 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

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

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

      Delete
  4. 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 ?

    ReplyDelete
    Replies
    1. 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.

      Delete
  5. 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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  6. 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 ?

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

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

    ReplyDelete
    Replies
    1. :-O :-) :-D Thanks very much.....

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    2. 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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  8. @ 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?

    ReplyDelete
    Replies
    1. The details are provided in the diagram.

      Diodes can be 1N5408s

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    2. 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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    3. please check out the updated (original) circuit in the article

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

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    6. can we use MIC 6A4 diode in power supply.

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  9. 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 :-)

    ReplyDelete
  10. 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

    ReplyDelete
    Replies
    1. I have posted the circuit dude.
      Lancy Felix.

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

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    3. 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

      Delete
  11. 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

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

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

      Delete
  13. 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 :-)

    ReplyDelete
    Replies
    1. Thanks for the help Lancy, keep it up mate:)

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

    ReplyDelete
  15. 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)

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

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    3. 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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  16. 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

    ReplyDelete
    Replies
    1. 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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  17. 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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  18. 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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  19. sir hoe to cut below 80HZ in low pass filter circuit

    ReplyDelete
  20. sir i want buffercircuit & bass boost circuit using op amp

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

    ReplyDelete
    Replies
    1. 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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  22. 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 !

    ReplyDelete
  23. 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 ??

    ReplyDelete
    Replies
    1. 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

      Delete
  24. 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.

    ReplyDelete
    Replies
    1. That's great support Lancy, Thanks very much.

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

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

    ReplyDelete
  27. 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 ......

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

      Delete
  28. 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.

    ReplyDelete
    Replies
    1. 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.

      Delete
  29. can you post a completed circuit with all parts

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

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

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  32. 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.

    ReplyDelete
    Replies
    1. 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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    2. http://i00.i.aliimg.com/photo/v0/309836240/TIP3055_Power_NPN_Transistors_ST.jpg

      then can I use this transister

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

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  33. is there a good quality bass in this amplifire.

    ReplyDelete
    Replies
    1. No, it does not include bass control, you will have to add it externally

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

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

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  34. 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

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

      Delete
  35. 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

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

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    2. ow do you have above amplifire pcb diagrame?

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

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

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

      Delete
  36. how can i contact you for a personal matter immediatly pleaseeeeeeeeeeee

    ReplyDelete
  37. 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" :)

    ReplyDelete
    Replies
    1. 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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    2. 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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    3. separate power supplies won't be required, you can use the same supply, just by making the grounds common...

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

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

    Correct? :)

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

    ReplyDelete
  40. 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.

    ReplyDelete
  41. 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?

    ReplyDelete
    Replies
    1. 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??

      Delete
  42. 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

    ReplyDelete
    Replies
    1. 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.

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

    ReplyDelete
    Replies
    1. use the following circuit

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

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

    ReplyDelete
  45. Hi Swagatam sir

    please send me the above pcb diagrams.

    my email id: bhudha@gmail.com

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

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

      Delete
  47. 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.

    ReplyDelete
    Replies
    1. 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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  48. 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.

    ReplyDelete
    Replies
    1. 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

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

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

      Delete
    2. 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?

      Delete
    3. 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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    4. 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.

      Delete
    5. 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.

      Delete
    6. 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.

      Delete
    7. 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.

      Delete
    8. Yes it will do...


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

      Delete
    9. 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.

      Delete
    10. 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.

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

    ReplyDelete
  51. 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.

    ReplyDelete
    Replies
    1. 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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    2. mono or stereo input is not the problem...the problem is surely in the amplifier circuit itself....

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    3. 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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    4. 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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    5. and can the V+ and ground terminals of the P1 interchangeable?

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    6. 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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    7. 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

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

    ReplyDelete
  53. 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/

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

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

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

    ReplyDelete

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Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.