100W MOSFET power amplifier
100W MOSFET power amplifier.
A 100W MOSFET power amplifier circuit based on IRFP240 and IRFP9240 MOSFETs is shown here. The amplifier operates from a +45/-45 V DC dual supply and can deliver 100 watt rms into an 8 ohm speaker and 160 watt rms into a 4 ohm speaker. This Hi-Fi amplifier circuit is suitable for a lot applications like general purpose amplifier, guitar amplifier, keyboard amplifier. The amplifier can be also used as a sub woofer amplifier but a subwoofer filter stage has to be added before the input stage. The amplifier has a low distortion of 0.1%, a damping factor greater than 200, input sensitivity of 1.2V and the bandwidth is from 4Hz to 4 KHz.
Circuit diagram.
100W mosfet power amplifier circuit
100W mosfet power amplifier circuit
About the circuit.
Capacitor C8 is the input DC decoupling capacitor which blocks DC voltage if any from the input source. IF unblocked, this DC voltage will alter the bias setting s of the succeeding stages. Resistor R20 limits the input current to Q1 C7 bypasses any high frequency noise from the input. Transistor Q1 and Q2 forms the input differential pair and the constant current source circuit built around Q9 and Q10 sources 1mA. Preset R1 is used for adjusting the voltage at the output of the amplifier. Resistors R3 and R2 sets the gain of the amplifier. The second differential stage is formed by transistors Q3 and Q6 while transistors Q4 and Q5 forms a current mirror which makes the second differential pair to drain an identical current. This is done in order to improve linearity and gain. Power amplification stage based on Q7 and Q8 which operates in the class AB mode. Preset R8 can be used for adjusting the quiescent current of the amplifier. The network comprising of capacitor C3 and resistor R19 improves high frequency stability and prevents the chance of oscillation. F1 and F2 are safety fuses.
Circuit setup.
Set R1 at midpoint before powering up and then adjust it slowly in order to get a minimum voltage (less than 50mV0 at the output. Next step is setting up the quiescent current and keep the preset R8 in minimum resistance and connect a multimeter across points marked X & Y in the circuit diagram. Now adjust R8 so that the multimeter reads 16.5mV which corresponds to 50mA quiescent current.
Notes.
- Assemble the circuit on a good quality PCB.
- Use a +45/-45 V DC, 3A dual supply for powering the circuit.
- Power supply voltage must not exceed +55/-55 V DC.
- Before connecting the speaker, check the zero signal output voltage of the amplifier and in any case it should not be higher than 50mV. If it is higher than 50mV, check the circuit for any error. Replacing Q1, Q2 with another set could also solve the problem.
- Fit Q7 and Q8 to a 2°C/W heat sink. Both Q7 and Q8 must be isolated from the heat sink using mica sheets. Heat sink mounting kits for almost all power transistors/ MOSFETs of almost all package styles are readily available in the market.
- All resistors other than R10, R11 and R19 are 1/4 watt metal film resistors. R10 and R11 are 5W wire wound type while R19 is a 3W wire wound type.
Power supply for the 100W MOSFET power amplifier.
+45 / -45 dual supply for the 100W mosfet power amplifier
A basic dual power supply is used for the amplifier circuit. If 6A ampere bridge is not available, then make one using four 6A6 diodes.C10 and C11 are high frequency bypass capacitors. Filter capacitors C8 and C9 must be at least 10000uF, higher the value lesser the ripple. Optional 3A fuses can be added to the +45 and -45 lines. Transformer T1 can be a 230V primary, 35-0-35 V secondary, 300VA step down transformer.
süpperrrr mosfet amp
not avail the transistor mje340/350. bd139/140 not suitable.
hi,can u plz send me the full pcb layout design, inc P.S
I’ve one doubt how to ctrl the vol of the amp?
also in the electronic shop the transformer is rated in ‘A’ not in ‘va’
,is 300va=6.5A?
Hello!
First of all i want to tell you that its a VERY LOUD amplifier even with dual 27V transformer,i will try it with 40v when i buy the new transformers, i have only one question, what kind of pot is the ideal to adjust the volume?
I use a 100k pot but when i turn it off i stil have sound in my speakers, a 1M ohm pot would be good or even it will be small?
Thank you very much!
Hi Theofrastos 100K logarithmic control that should take care for volume problem at lower settings, do not use Lin controls.
sir,can i pls get the circuit theory analysis of the 100watt mosfet amplifier.my email:treborzonelife@gmail.com
sir,can i pls get the circuit theory analysis of the 100watt mosfet amplifier.
Hello, both my transistor burned out in 2 secounds (Q8 and Q7), what can cause this problem? I have also changed the value of pot R8 to 5k (i could’t find any 3k pot multiturn from my store) but i dont think it have anything to do with the burn transistors ? Thanks for the help
Hi Niklas in the place of R8 put a link. Reduce the fuse rating to 500mA. If every thing is oK it should stay alright if the fuse blows indicates something wrong in the wiring. Please check and correct and proceed as above. If it is ok replace link with say 2k2 pot and set the current through the fuse for 50 to 60 mA.
Hi… plz, provide me the pcb layout. My mail ID: prakash_bytari@yahoo.co.in
sir i want to construct an inverter using eight IRFT250N four in opposite side. what size of transformer will be suitable for this construction. thanks
whenever i connect the circuit, the resistor R7 burn out…
i could not collect the mosfet IRFP240 & IRFP9240…instead i used two IRF9240 with proper biasing. please help…
Hi, I’m a little confused here…. looking at setting R8 for 16.5mV across 2 x 0.33 ohms looks like 25mA to me? Am I missing something or should the measurement be across just 1 x 0.33 ohm OR 33mV across points X to Y? Thanks, Baz
Hi Baz you are correct.
Hi Ifte without feeding any input to the amplifier (say volume control fully closed no sound from speakers)connect a multimeter across points marked X & Y in the circuit diagram and adjust R8 so that the multimeter reads 16.5mV which corresponds to 50mA quiescent current.
1. what is zero signal output voltage of the amplifier? and how can i measure it?
Hi Harry as per following link it is a good performer.
http://schematicwiringdiagram.blogspot.in/2011/08/100w-mosfet-power-amplifier-based-on.html
tell me anyone using this amplifier is this working?
thanx Seetharaman, but this is a 400W mosfet amplifier layout how can i use it for 100 W mosfet amplifier.
Hi Harry can be used.
Use the following link for your PCB layout
http://hobbyelectronicsdri.blogspot.in/2011/06/400w-mosfet-amplifier-circuit-with.html
Dear Sir…
Can I get the PCB for the same or atleast PCB Layout…pls reply..
Ramdas
plz give me a reply………
i have a 35-0-35 5Amp. transformer is this suitable for this amplifier
hi……..
i build this amplifier but when i switch on the power supply the IRFP9240 heats up and gets burn. so what should i do. i want ur help guyz…….
reply
Hi to all
someone have the PCB layout for this amplifier?
many thanks in advance
I need 200watts(rms)amplifier circuit diagram
Pcb
This escheme was not designed for this author. This amplifier work fine, but in the scheme displayed here, have some issues. The “pots” (R8 and R1 must be mult turn), the value of R17 is not a 47K. The R17 must set a current aprox of 1mA, so, we need a 330r to 470r. R*I=U, R=?, I=0,001A U=0.650v,(equal a VBE voltage). Do the calc, and see for yourself. Be carefully for use others MOSFET. The bandwidth is 3,6Hz to 39.4KHz. Don’t exceed 55V dc for each rail. All that you need is 40+40AC 225VA trafo for each channel@160Wrms/4ohms. Good Luck.
Brazil.
T7 = IRFP240, 2SK1530, 2SJ162, BUZ900DP, BUZ901DP (take care for pin layout : GDS GSD)
T8 = IRFP9240, 2SJ201, 2SK1058, BUZ905DP, BUZ906DP (take care for pin layout : GDS GSD)
This escheme was not designed for this author. This amplifier work fine, but in the scheme displayed here, have some issues. The “pots” (R8 and R1 must be mult turn), the value of R17 is not a 47K. The R17 must set a current aprox of 1mA, so, we need a 330r to 470r. R*I=U, R=?, I=0,001A U=0.650v,(equal a VBE voltage). Do the calc, and see for yourself. Be carefully for use others MOSFET. The bandwidth is 3,6Hz to 39.4KHz. Don’t exceed 55V dc for each rail. All that you need is 40+40AC 225VA trafo for each channel@160Wrms/4ohms. Good Luck.
Hi Joel this amplifier’s bandwidth is 4Hz to 40KHz, which is quite fine for audio use. what is written is wrong a zero is missing in the upper limit.
@you can u go and check the parameter of irfp240 and see if there is any similarity at http://www.alltransistors.com
Bandwidth is too short how can i increase it i need at least 15KHz
Hi Gamerandds most economical IRFP540 / 9540 pair also can be used. It can work with 4 ohms speaker delivering around 200watts. below this impedance it is risky to operate the amplifier it may blow the FETs.
WILL THIS RUN ON 2 OHMS STABLE?
Will the Irfp250 work instead of the 240 in this circuit?
Hi Mike you can try is the standing current is not raising to required level with R8, you may have to raise R8 to 4.7k pot. otherwise it should work.
gud day, s it possible to use 35v instead of 45v for the power supply of this circuit?tnx
I will make a pbc for this circuit if u want it just ask, but has anyone considered using Irfp250 for this circuit instead? I dont wanna just buy 20 if them and they don’t work. ???
Selanco add another pair of mosfets with it’s own resistors, I’m planning on adding 4 more to get around 500 watts rms. Remember that in 4 ohms one pair can Play up to 160 watts!!
Does bass preamp will work like a filter?
Hi!
Will this circuit work for a bass amp/combo? I think that it will do the job, but I want to be sure. Also has anyone saw or made/could make, a pcb project for this schematic?
Cheers from Poland
This amp will work, but you have to add a filter circuit at the input.
dear sir,
i need 200watts (rms) mosfet subwoofer amplifier circuit diagram.