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High Power 250 Watt MosFet DJ Amplifier Circuit

High Power 250 Watt MosFet DJ Amplifier Circuit

The powerful DJ 250 watt mosfet amplifier circuit design provided in this article is reasonably easy to build and will produce thumping music into the connected loudspeaker.Use of HEXFETs at the output ensures monstrous current and voltage amplification.

The involvement of MOSFETs or rather HEXFETs at the output stage of this 250 watt mosfet amplifier circuit promises high and efficient amplification of both voltage and current. The circuit particularly exhibits impressing features like low distortion and external offset voltage and quiescent current adjustments.

Amplifier Input Stage

 

250 Watt MosFet Amplifier Circuit

 

Amplifier Power Output Stage

 

 

250 Watt MosFet Speaker Output

How the Circuit Functions

This outstanding 250 watt mosfet amplifier circuit can be used as a DJ amplifier in concerts, parties, open grounds etc. The design being symmetrical produces negligible distortions. Let’s try to analyze the circuit details:



Referring to the circuit diagram, we see that the input stages primarily consists of two differential amplifiers. The blocks T1 and T2 are actually matched paired dual transistors in one package, but you may go for discrete transistors, just make sure their hFes are properly matched. Use a couple of BC 547 and BC 557 for the NPN and the PNP types respectively.

A differential configuration is probably the perfect way of integrating two signals, for example here the input and the feedback signals are mixed so efficiently.

Typically the ratio of the collector/emitter resistances of T1 determines the amplification of this stage.
The DC operating reference for T1 and T2 is received from a couple of transistors T3 and T4 along with the associated LEDs.

The above LED/ Transistor network also helps to provide a constant current source to the input stage as it virtually remains unaffected to ambient temperature variations, but preferably the LED/ transistor pair should be attached together by gluing them together or at least soldered very close to each other over the PCB.

Immediately after the coupling capacitor C1, the network comprising of R2, R3 and C2 forms an effective low pass filter and helps maintaining a bandwidth to a level suitable for the amplifier.
Another small network at the input, involving a 1M preset and a couple of 2M2 resistors helps adjusting the off-set voltage so that the DC component at the output of the amplifier stays at zero potential.

After the differential stage an intermediate driver stage is introduced comprising T5 and T7. The configuration consisting of T6, R9 and R17 forms a kind of variable voltage regulator, which is used to set the quiescent current consumption of the circuit.

The boosted signal from the above stage goes to the driver stage consisting of T8 and T9 which are effectively used to drive the output power stage involving the HEXFETs T10 and T11 where the signals ultimately undergoes a massive current and voltage amplification.

From the diagram it is clearly identifiable that T10 is a p-channel and T11 is an n-channel FET. This configuration allows efficient amplification of both current and voltage at this stage. The overall amplification is though limited to 3 due to the feedback wiring of R22/R23 and also with R8/C2. The limitation ensures low distortion at the output.

Unlike bipolar transistors, here the outputs stage incorporating HEXFETs have a distinct advantage over its age old counter part. HEXFETs being positive temperature coefficient devices are equipped with the inherent property of limiting their drain source as the case temperature tend to get too hot, safeguarding the device from thermal runaway situations and getting burnt off.

Resistor R26 and the series capacitor compensate the rising impedance of the loudspeaker at higher frequencies. Inductor L1 is placed to safeguard the loudspeaker from instantaneous rising peak signals.

Parts List

R1 = 100K

R2 = 100K

R3 = 2K

R4,5,6,7 = 33 E

R8 = 3K3,

R9 = 1K PRESET,

R10,11,12,13 = 1K2,

R14,15 =470E,

R16 = 3K3,

R17 = 470E,

R18,19,21,24 = 12E,

R22 = 220, 5 WATT

R20,25 = 220E,

R23 = 56E, 5 WATTS

R26 = 5E6, ½ WATT

C1 = 2.2uF, PPC,

C2 = 1nF,

C3 = 330pF,

C6 = 0.1uF, mkt,

T3 =BC557B,

T4 = BC547B,

T7,9 =
TIP32,

T5,6,8 = TIP31,

T10 = IRF9540,

T11 = IRF540,

An alternate version of the above explained 250 watt power amplifier can eb seen in the following diagram having all the details regarding the components:
160 Watt complete Amplifier Design with Pinout

 

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About the Author

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. If you have any circuit related query, you may interact through comments, I'll be most happy to help!






82 thoughts on “High Power 250 Watt MosFet DJ Amplifier Circuit”

  1. hi sir am looking for 160 watts rms 4 ohms sub woofer amplifier single channel. can u suggest any power amp IC or mosfet based circuits .

  2. Hello sir both the circuits that you have sent to me are working and thanks very much and another thing to ask you sir is which ic is better or good for audio amplifier that is la4440 or stk 4141

    • Hello Raghvendra,

      I am glad it worked for you! both the ICs are almost similar with their specs, LA4440 is slightly lower in wats than the STK4141, Its 19 watts while the STK is 25 watts…but STK looks quite obsolete now…

  3. Hello Sagatam Majumdar. There are inconsistencies in the values of some of the parts between the schematic at the bottom of the page and the parts list. For example, C3 and C6. They have a value on schematic and a value in part list. Witch one is the correct value?
    Thank you

    • Hello Mihai, slight differences in the component values will have no affect on the designs…however you can preferably go with the last diagram which is the original one.

    • Vijay, there's only a standard method to test BJT and mosfets….BJTs are easy to test but mosfets are not….you can refer to youtube and search this, you will be able to find some video tutorials….

      but you will have to remove the transistors from the PCB before checking them.

    • Vijay, sending PCB image will not help, you will have to troubleshoot it yourself, or build it again from the scratch, it's not so difficult…..keep trying you will succeed.

    • All these circuits are taken from elektor electronics magazine, and these have been tested by the elektor electronics engineers.

    • If the ammeter is showing nothing then how come R16 is getting hot?

      check quiescent current by shorting the input terminals, and by removing the speaker….don't short the output.

    • Vijay, that means you might have other faults also, or a transistors may be faulty or wrongly connected….I cannot troubleshoot your circuit without seeing it.

  4. Sir I made PCB and all parts placed but no sound only humming sound in speaker,
    I connected multimeter plus to output and mins to GND, range 20v DC for feedback reading its getting 15v and no
    Variable even I adjusting R9 i.e 1k port

  5. sir, already i brought parts as per old circuit(total=800 Rs), so lets continue.which is that first R5 & C2 or after that? and (small doubt it will work)

    • No it could be a mistake, the values are not same I don't remember now, I'll have to check it in my old books, it may take little time may be two days

  6. all parts are ready to built, but little confustion what is T1 & T2 (any other alternate transistor if not aveailabe pair transistor)

  7. sir in need a circuit for 3phase induction motor protection which can automatically switched off the motor when it is over heated or one phase is off or phase is reversed or ov and uv protection

    • Vivek, connect the matching dotted lines of the two images with other, for example the (+) will go to the (+) line, (-) to the negative and so on

  8. In this ckt which type of diode is used and value mention diode d1 and d2 as given in ckt?
    And which type of inductance and value?
    Where i connect audio in hub or audio in socket?

  9. Thanks so much for the detailed explanation. But one thing I would like to know before building it; have you or anyone else actually built the circuit using the given values?

  10. Hi Sir, what happens to power sharing & output in an amplifier using transistors A1943 & C5200 because each is 100W power dissipation(power calculations of the output stage)?
    And what most contributes to how powerful an amplifier can be in TRANSISTOR AMPLIFIERS?

    • Hi kakooza, the transistor number is not important, it's the specifications that matter, if the specs match then the transistor will work as efficiently as expected from them.

      the output devices primarily decide the power level of the amplifier, but only if the power supply is optimally rated, lower supply specs will result in poor output quality and distortions.

  11. I have 4 ohm super speakers.. will you help to make a amplifier at home for suitable for this 4 ohm speakers with simple way to understand circuits and gave a proper list to used equipments in this…………… please help me…

  12. I have two 6 ohm speakers and want to build a speaker system with very good quality right from scratch( from 3.5 mm jack). Got any circuit for that?

    • You can do it, the power would increase substantially, just make sure to add a 0.22 ohm 1 watt resistors in series with the source of each mosfet, and also use separate gate resistors for each mosfets.

  13. It's a standard design having a differential stage, followed by a driver stage and finally a power output stage.

    The transformer will need to be made-to-order, the high voltage is necessary for implementing the extreme high wattage output from the circuit, and for keeping the wires and the transformer dimensions smaller.

  14. Thanks for the link sir.
    Could you please explain the circuit diagram? Also i doubt if i can find suitable transformer for the power supply section in my country. I have been searching with no result yet. can you suggest the way out?
    Thanks

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