15W Class C Audio Amplifier.

Thread Starter

mishra87

Joined Jan 17, 2016
1,040
Hi everyone,
Can anyone help me to get the 15W class C amplifier using only transistor bjt.
Any direction is highly appreciated.
Thanks in advance
 

Thread Starter

mishra87

Joined Jan 17, 2016
1,040
What frequency?
Hey...thanks for your reply...
I am not much expert on that..The application says the 15W class C amplifier has to be connected with Radio to produce Sound.../
Based on your experience and knowledge You can choose the frequency.
It is better if you show me in LTspice.
Thanks once again in Advance !
 

MisterBill2

Joined Jan 23, 2018
19,052
You CAN use a class C amplifier for audio BUT you will have at least 50% harmonic distortion, probably more.
Please let us know the source of this application.. ".The application says the 15W class C amplifier has to be connected with Radio to produce Sound." It seems very much like something from that website that I do not respect. There has to be a lot missing to come across as that message.
 

MisterBill2

Joined Jan 23, 2018
19,052
The early ones were class A with a germanium power transistor in a TO-3 package. Probably had a dangle-biased 1-transistor preamp.

ak
It was more likely class "B", because that consumes a fair amount less power. I recall those i960's guitar amp boosters: transformer coupled input and output and a fair amount of crossover distortion. But a great way to get an extra hundred watts.
AND, very seriously, I want to see the application that made this statement. It would be interesting to see what goes with it.
 
I also recall seeing an AM car radio with a single, TO-36 germanium transistor at the output stage. The transistor drove a transformer to which the speaker was connected.
I didn’t have access to a scope to confirm, but very likely it must have been class A.

1713499601293.png
 

DickCappels

Joined Aug 21, 2008
10,236
If this is for real-life use, you can use one of the many integrated audio amplifier chips. Have a look at the mature (ancient) TDA2030. I bought a bunch in the early 1990's and in the 201X timeframe was pleased to see that they are much less expensive now...and they worked great.
 

Ya’akov

Joined Jan 27, 2019
9,246
I also recall seeing an AM car radio with a single, TO-36 germanium transistor at the output stage. The transistor drove a transformer to which the speaker was connected.
I didn’t have access to a scope to confirm, but very likely it must have been class A.
The classic Motorola transistorized car radios used a single Ge device in a Class A configuration—hot, very inefficient, but transistors were expensive, so that was the driver (so to speak). I am sure any other manufacturer was doing the same thing, but Motorola got its name from these radios—Moto (from motor, slang for car) and -rola (from VIctrola, a record player).

1713521233089.png
 

DickCappels

Joined Aug 21, 2008
10,236
Motorola: Consider that the engineer(s) who developed the bipolar class A stage were probably the same ones who designed earlier vacuum tube versions. That was before the (U.S.) CAFE standards that made fuel economy and thus weight and efficiency very important.

When I had a car with a tuner but no audio amplifier I made one with a transistor Darlington driving an audio output transformer salvaged from a tube-type radio. It was not loud but it fit my Jr. Technician's income at the time. As I recall they were both Motorola transistors.
 

AnalogKid

Joined Aug 1, 2013
11,156
It was more likely class "B", because that consumes a fair amount less power.
That is so 1970's thinking. The bullhorns I repaired had two transistors, one TO-5 and one TO-3. A fair amount of DC went through the speaker, which was the entire collector load.. IIRC, there was one with a carbon mic and only the one power transistor. Fun times.

ak
 

BobTPH

Joined Jun 5, 2013
9,182
Hi all,
Thanks all for your response.
Lets do any class C audio amplifier using only bjt.
Thanks !
Emitter to ground.
Speaker between collector and V+.
input to base.

Input source needs to be about 2V min with about 100 to 1K output impedance.

It will sound terrible, amplifying only a portion of positive half if the input.
 
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