hi,
By using the power amplifier below.
when i measure the collector pin of both Q3 & Q4 using a scope i get the waveform below. This waveform is outputted when the volume is low.
when i tune the volume slightly higher.I get this.
And the pic below show the comparison between Q3(Collector) & Q1 (collector).
From the first waveform, i can see that the Voltage level of Q3(C) is complement with Q4(C). Does this mean the push-pull characteristic?
Another ques is how could the voltage go up and rapidly down in such a way? which part is controlling the up and down.
When i tune the volume lower there is no signal inside the triangle waveform.But when i tune the volume higher it seems like the audio signal which i inputted carry by the triangle waveform. Can someone explain on this?
thank you.
By using the power amplifier below.
when i measure the collector pin of both Q3 & Q4 using a scope i get the waveform below. This waveform is outputted when the volume is low.
when i tune the volume slightly higher.I get this.
And the pic below show the comparison between Q3(Collector) & Q1 (collector).
From the first waveform, i can see that the Voltage level of Q3(C) is complement with Q4(C). Does this mean the push-pull characteristic?
Another ques is how could the voltage go up and rapidly down in such a way? which part is controlling the up and down.
When i tune the volume lower there is no signal inside the triangle waveform.But when i tune the volume higher it seems like the audio signal which i inputted carry by the triangle waveform. Can someone explain on this?
thank you.
I need additional the waveform of input signal for reference. And I need the waveform of the residual AC signale between the pos rail and GND so as neg. rail and GND.
If you have already a sine wave signal as input, your device is an oscillator instead an amplifier - I guess.
Wiring management and mass (GND) management by such amplifier is always critical. Without experience in most cases you will have an unwanted oscillator effect.
The problem could be from filter cap in combination with some other things. But not allone from filter cap, because the high frequency saw tooth isn't to see here.
The showing of a second wave form with higher frequency by higher volume is for me clearly indicator for parasitic oscillation through unwanted influences of one or several faulties by wiring and PCB design. Check out the links from my first answer here and compare your device with that one from the URL of Spain kit supplier.
And the mentioned missing parts by post #11 this oscillation by higher volume adjust can't actually cause.
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In which condition?
With or without load?
With or without Boucherot network to GND?
In which input condition?
Input short or Input open?
Which input signal?
Some other boundary conditions are very important to know for deliver helpful advices.
Please note: even perfectly designed and built amplifiers can oscillate without loudspeaker load or Boucherot network to GND.
For certainly circuit concepts, it can also be reversed. But in such cases there are hugh design/wiring errors.
I recommend to buy some books about amplifiers. Any suggestions you will find there:
http://www.diyaudio.com/forums/solid-state/158055-best-books-about-solid-state-amplifiers.html
From that one of J.Curl's post #7 I would start.
The DIY kit i bought which is this New Page 1 has a 40watt + 40watt transistorised stereo power Amp. Is it suitable to connect it to a pair of speaker with a spec of max power 200Watt, nominal power 80watt, impedance 4ohm? usually how do we know that what type of spec of the speaker should be use for different type of power amplifier kit?
thanks.
thanks.
I looked at that too, but there's no scale on the scope. How much is the ripple actually? it may be fraction of volts.
jd
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