Beta for this transistor:
MPS2907. Data sheet gives
DC Current Gain
(IC = −0.1 mAdc, VCE = −10 Vdc)
(IC = −1.0 mAdc, VCE = −10 Vdc)
(IC = −10 mAdc, VCE = −10 Vdc)
(IC = −150 mAdc, VCE = −10 Vdc) (Note 1)
(IC = −500 mAdc, VCE = −10 Vdc) (Note 1)
75
100
100
100
50
So, why only 35 then? This particular circuit (with bias network = 75k/10k) draws about half a mA of quiescent current, so for most of the voltage swing beta should be above 75 and generally closer to 100. Plus you may have noticed that these are given as
minimum values, and the graph of
typical beta at normal temperatures is well above 100 even at 0.1 mA Ic.
Be careful to avoid using transistors in areas of heavy beta droop, which is above about 200-400 mA in this case. This could lead to some nasty effects, not to mention that GBW (datasheet Fig. 10) is dropping like a rock and may be good for some nasty intermodulation distortion.
I presume you mean the 5 uF capacitor and the 1Mega Ohm resistor on the right side of the diagram? OK. That did not do any harm, the output sine wave amplitude increased about threefold.
Are you sure it's not just the scaling that changed?
I simply do not understand this part - 500 mVp - millivolts ? p?
There are a few different ways of specifying AC amplitudes in periodic signals:
peak-to-peak: The distance between the very minimum and maximum of the waveform. If the latter is described as f(t) = A sin(ωt), the peak-peak amplitude is 2 A. Peak-peak voltages are given in Vpp or Vp-p (using any SI prefixes you can think of).
peak: The difference between zero volts and maximum amplitude, assuming a symmetrical waveform. For our sine f(t) = A sin(ωt), the peak amplitude is A, exactly one half of peak-peak voltage. Peak voltages are given in Vp. I used this because it is what the voltage source in simulation is set up with.
RMS (root mean square): The time integral of the waveform. This is useful for power comparisons to DC. For our sine f(t) = A sin(ωt), the RMS amplitude is sqrt(2) A. RMS voltages are given in Vrms.
In systems of known (load) impedance, it is common to specify load power levels instead, so you might see mW or W into N ohms. dBs referred to known power levels are also commonly used, e.g. dBm (re: 1 mW) or dBf (re: 1 fW) in RF. The dBu you find in pro audio also derives from there originally (nowadays re: 775 mV, which happens to be 1 mW @ 600 ohms - but nobody uses 600 ohm inputs in PA any more).
In any case the AC input is set as 500Mv however for an actual input from a mini rca output such as from a phone or MP3 player how can I reduce the output?
Using the volume control on said device sounds too simple...?
Otherwise, a voltage divider?
BTW, there is no such thing as a "mini RCA", you surely mean a 1/4" / 3.5 mm minijack.
I need to do more reading, but these electronics sites are confusing especially the circuit diagram with the infamous "ground". I really wold prefer if they showed two terminals.
You're actually in good company there (Bruno Putzeys claims to never have seen a one-terminal voltmeter either). "Ground" is a shortcut that makes for neat and tidy schematics, nothing more. It's a node that you declare
Your Reference Potential. Now a physically extended node that keeps the same potential everywhere
under any and all conditions does not exist, of course - finite conductivity and inductance have a say in that. Hence why in layout, considerable effort may be invested into getting the grounding right. Currents do, after all, flow in loops, and things may get ugly if large and distorted currents share the same paths with very small but critical ones.
I do think you should look for a good electronics textbook.
