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what type of High frequency?

Excuse me Forum, But what type of a frequency would make the voltage on the Base Emitter junction of a BJT 0.22Volts?
The transistors are not damaged, But in my volt meter, I am reading A 0.22 up to even 0.09 volts(???). When the frequency increases. Its a voltage booster and that's why I am Very Suspicious.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
If you're trying to read AC on a DC meter, you're going to get wildly incorrect readings - the frequency makes relatively little difference, it's essentially the mark/space ratio that affects it, as the meter will 'attempt' to average it out.

Basically it's pretty pointless trying to take readins with a meter, you need a scope.
 

JimB

Super Moderator
Most Helpful Member
I am reading A 0.22 up to even 0.09 volts
Don't you mean 0.22v down to 0.09v ??

what type of a frequency
My first guess would be a frequency which is too high for you meter to measure accurately.
All meters have an upper frequency limit, have a look at the specification for your meter.

JimB
 
Oh, I don't have an oscilloscope yet, But I'll have one soon, Its just very suspicious and awkward. But from what is on my eyes, It looks like its above 300khz switching FREQ.
Anyways, Is it doing to damage my transistor?
By the way, Transistor is D882 and DMM is DT830D
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Oh, I don't have an oscilloscope yet, But I'll have one soon, Its just very suspicious and awkward. But from what is on my eyes, It looks like its above 300khz switching FREQ.
Anyways, Is it doing to damage my transistor?
No, it's just that you're trying to do something that won't ever work - a multimeter is completely unsuitable for making any meaningful measurements in such circumstances.

Why are you even trying to measure it?, there doesn't seem much of a reason to want to do so?.
 
And as for why I am measuring the base emitter voltage, I am testing if the base emitter diode voltage (VBE) decreases with Higher frequency.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
And as for why I am measuring the base emitter voltage, I am testing if the base emitter diode voltage (VBE) decreases with Higher frequency.
Again, why? - what do you hope to achieve by it? - and it's not anything you could measure with a multi-meter anyway.

Is this some kind of school assignment?.
 

JimB

Super Moderator
Most Helpful Member
Well, atleast, I have a new Task; Find a new DMM.
Was this inspired by my comment:
My first guess would be a frequency which is too high for you meter to measure accurately.
All meters have an upper frequency limit, have a look at the specification for your meter.
To buy a new meter on that basis would be a poor way to spend your money.

If you want to extend your electronics capabilities and better understand devices with AC, square waves and pulses, you need an oscilloscope.

JimB
 
Nope, Its just for the sake of the "Electronics at Home". By the way, Some DMM's have oscilloscope's right?
Or I'll just have to buy a pocket oscilloscope + a new DMM.
Electronics at Home :)
 

ChrisP58

Well-Known Member
Well, I would reverse that to say that some scopes have some DMM functions.

Here is one that does. But it only has a 25MHz bandwidth. You'll need to decide if you need something faster.

But, if you get a scope for it's waveform display capabilities, do you really need it to have DMM functions? I assume that your existing meter works for what it's supposed to do.

Personally I'd rather spend the money on a better scope.
 
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