Audio Amplifier using TIP 147, 142

I have made an Audio Amplifier using LM386 IC but it does not amplify any sound from Microphone. Please help me to improve this using darlington pair or any other power transistor like Tip 147, 142

Hi,

here is a sample circuit in which you can follow: http://www.circuitsgallery.com/2012/08/Simple-audio-power-amplifier-circuit-TIP.html

Unless you already have your circuit, this will be a good help for you.

Hi ,Usama

It is not the problem of the amp circuit, your mic signal requires a pre booster use
this circuit along with your amp circuit.check the base to emitter voltage it should be 0.6v
if it is less adj the value of 82k to 68k see the circuit attached.

Regards V.Sambath kumar

thanks for the answer.
I have right now 2N3904 so could i use it ... also i have electret microphone please tell me hoe to install it.

Hi Usama khurram,

Since you are using an electric mic pl go for this ckt. ref my attachment.



Cheers, V.Sambath kumar.

Thanks sir for the prompt response and guidance.

Last night i made this circuit and it works and amplifies sound very high but some *distorted please help me where i need to make variation for the clarity in signal*. I was taking signal from my laptop and output voltage I check from meter was *4.5 volts* and respective current is *450 mA* around. I have attached my mic and installation picture of mic with the help of YouTube image but it does not work. please guide me.. will your recent insightful circuit for mic work for it or any changes is required? also i want to enhance this circuit to amplify it more to make it about *25 watts*.

Hi Usama khurram,
1 your signal out put level is very high reduce it add a 2.2 uf cap 63v positive terminal in series towards the lap top signal out put jack and negative to a 22 or 33k resistor and feed the signal to the in put of the amplifier.or provide a 47k preset short the centre pin to one side end of preset and put in place of the 33k resistor in series and vary it to suite your requirement.
2 if you want to use the mic ,use the circuit i have given connect it to the input of amp ckt.dont feed the audio out of the laptop to the mic in put ckt it will howl or get distorted since the signal level is very high ,any audio signal up to 50 to 60 mv is considered as a mic signal and above that is considered as a line signal. The body of the cond mic should be connected to the gnd /negative supply

usually pre amp ckt consume around a max of 10ma to 30ma.
you can also connect a 100k resistor from the top end of your amp volume control to gnd to reduce further distortion if required.



Cheers, V.Sambath kumar

Attached is the circuit which i made so far using the combination of tow circuits. One is Pre-Amp circuit which you sent me with the Amplifier circuit. Everything is attached. I have made some changes in the circuit and now following issues I have been facing:

1: Mic is working but it does not give much sound as it should be. I'm not using 2.2Uf capacitor in the pre-amp circuit as it give very low signal.I am giving direct signal to the "Audio power amplifier circuit... which is in Green pic"

2: My circuit is for 30 Volts but I'm using 24 volts for this, so i think might be this reason?

3: Two Power Transistor of TIP31 (Q5, Q6) which you will see in the "Green circuit" became hot and melt the breadboard so what is that reason of heating up. I have 2 power supplies. when I power up this using 24 Volts/ 1.5amp it does work fine. But when i apply 15 volts / 3Amp then it became hot. what is the reason.

4: I'm using 250Kohm resistor for R10, and 500Kohm resistor for R9 in "Green circuit" which control the amplification and gives better sound. but when i remove 500Kohm to 0Ohm then sound is blast and distorted. I'm using 40 watt and 4Ohm speaker.. How may i control or clear it?

Please find the solution and update me promptly .. thanks in advance..

Hi ,usama khurram

1. with out using 2.2 uf your out put will get distorted because the dc voltage is directly fed to the vc. 2. Add a 4.7 ohms 10 watts resistor series to the supply voltage, reduce the supply voltage to 15v. 3. use heat sink for q5 and q6 change all controls to the orginal values. as in the ckt. Adjust R10 1k to set half of the supply v ie7.5 v in case of 15v supply
at the +ive of capacitor c4. before doing this check all the transistors and biasing resistors for any short open or for resistors going high value . 4. put the actual value R9 & R10 as per ckt. use a 8 ohms 20 watts full range speaker 40 watts is very high for this ckt. conduct a cold check of the output and driver transistors before doing any thing.



Regards V.Sambath kumar.

Thanks, can you please recommend me any "Sound Reactive LEDs" circuit for this. as i'm using the following circuit with same specs but it does not work. please suggest me.

Please make a quike review on my projects .. it gives no sound or give some small distortion, but when i put my finger on "2N3904" component from back of PCB highlighted in the images it works and give nice sound and after some time 20 to 30 seconds it back to original said state. please tell me what should do..