problem of boost converter

[goli619]

I have create a boost converter 12v to 45v. It is working well when i use 0.25Watt resistor(as a load). But, when I change load resistor into 0.5watt 10k resistor, "hiss" sound comes out and resistor is getting hot over the time ( i didn't connect the supply to the circuit for very long when the 'hiss' sound comes out).

in addition when the resistor is 0.5watt type, it will have a small spark when i connect the battery...

So, my problem now is :
1. Where is the 'hiss' sound coming from? From which component???
2. The spark indicates??

 

[Prototyp_V1.0]

There is only one component that have moving parts. Guess what? Hint: Think small.

Where do you locate the spark?

 

[goli619]

There is only one component that have moving parts. Guess what? Hint: Think small.

Where do you locate the spark?

Variable resistor?

Spark at terminal of the battery when i am trying to connect .

 

[Prototyp_V1.0]

The spark when you connect the battery occurs because the capacitor act just like a short the moment you connect the battery.

The pot I guess will spark a little because the connection to center tap isn't good. Is it an old one?

 

[keith1200rs]

The hiss will be from the inductor.

@Prototyp - if you want to be helpful, answer questions instead of starting a guessing game.

Keith

 

[goli619]

The spark when you connect the battery occurs because the capacitor act just like a short the moment you connect the battery.

The pot I guess will spark a little because the connection to center tap isn't good. Is it an old one?

Old Pot? You mean the model or what? I just bought it... So, is there any solution for it?

---------- Post added at 15:32 ---------- Previous post was at 15:31 ----------

The hiss will be from the inductor.

@Prototyp - if you want to be helpful, answer questions instead of starting a guessing game.

Keith

Why my inductor will generate the sound? Value is too large? Amp rating is not enough?
Thanks...

---------- Post added at 15:33 ---------- Previous post was at 15:32 ----------

@Prototyp and @Keith... Below is my current design with the rating

 

[keith1200rs]

The inductors often make a noise in switching regulators. The wires can physically move. It is usually worse if you make them yourself. Commercial ones are wound tighter and could be dipped.

Another factor can be frequency - a lot of regulators now run outside the audible range - does yours? It can also change with load if the operation becomes discontinuous.

Keith

 

[goli619]

The inductors often make a noise in switching regulators. The wires can physically move. It is usually worse if you make them yourself. Commercial ones are wound tighter and could be dipped.

Another factor can be frequency - a lot of regulators now run outside the audible range - does yours? It can also change with load if the operation becomes discontinuous.

Keith

Then, is the 'noise' dangerous? damaging my circuit?

Erm, I don't quite understand your 2nd paragraph, could you please explain more in detail? Sorry ya and thanks for your explaination..

 

[keith1200rs]

No the noise isn't a problem - more annoying than anything else. Think of the coil as a sort of loudspeaker.

Even if your circuit works outside the audio frequency, say 100kHz, you can still get a audible noise under certain loads. Depending on the circuit design and the feedback loop the circuit can "pulse" - doing a burst of oscillations then stopping for a short while. This could be a burst for 100us followed by a 200us gap, for example. That will make a sound with 3.3kHz components in it, so it will be audible.

Keith.

 

[goli619]

It's good to know the noise is not damaging... I was so afraid that the circuit will "BOOM" =.=''
THANKS