Twisted Transistor

174

01:42:43

Does anyone know how or why this is happening? If you look after the pnp transistor I'm reading over a 100 volts where almost the rest of the circuit is reading 0 . If you change anything such as remove the capacitor, change polarity on transistor, up DC voltage,ect., it drops back to "normal" range except , the smaller you make the capacitor beyond it the higher the voltage reading goes. Just wondering why?

published 8 years ago

jason9

8 years ago

I’m not sure what you’re talking about. No such readings show up for me.

Eeric82

8 years ago

If you mess with the capacitor beyond the pnp like increase it to 1uf then decrease it back down itll start to sgow the reading

Eeric82

8 years ago

Adjust capacitor up to 1 uf then back down to around 2 nf it'll show... At around 100 pf she'll read at about 2kv

selman

8 years ago

Voltage = Charge / Capacitance or V = Q/C. If you increase C, Q remains the same and V decreases, if you decrease C, with Q unchanged then V increases.

BillyT

8 years ago

Basically as selman has stated, In real life you cannot change the value of a capacitor in alive circuit, if you could the same thing would happen. What you have is a capacitor with some amount of column charge in it (V x I), if you change the value of the capacitor, the amount of voltage will change to try and rebalance this charge. This is the reason a circuit should be stopped and restarted when a component value is charged, if you want to see how that change really has affected the circuit.

hurz

8 years ago

@selman, thats exactly how everycircuit handels capacitors while simulation! @BillyT, do you know what microphonic effect of an capacitor mean? Try it yourself and connect a capacitor to an amplifier, charge the cap over an ohmic DC bias and hit the capacitor with a screwdriver, the vibration is exactly this effect. Cuz the capacitance does change and the voltage is modulated according to Q=CU

Eeric82

8 years ago

Thanks everyone, I'm learning more everyday.

thebugger

8 years ago

Yeah, capacitance can change. For instance with varicaps, but that's just how EC handles the abrupt change in capacitance. In reality this won't happen.

hurz

8 years ago

Abrupt buggzy

BillyT

8 years ago

@hurz, interesting .....

hurz

8 years ago

@BillyT, any chance for you to test that yourself?

BillyT

8 years ago

@hurz, not at the moment, but I can visualize what you are saying.

hurz

8 years ago

It just needs an opamp as amplifier.

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