The weakness of the CEN topology is the distortion cause by the early effect ( the zout of the input transistor is not constante), one way to improve this aspect, is to use a more powerfull transistor like the MJE15032/33. There are others good ones like the biss transistors from nxp.
In this circuit below we have 0.000086% at 8ma pp, the circuit consumes 25ma from the batteries.
This uses Bob Cordell models so i expect to be acurate.
In this circuit below we have 0.000086% at 8ma pp, the circuit consumes 25ma from the batteries.
This uses Bob Cordell models so i expect to be acurate.
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As I hinted in my post above, the 327/337 are actually -very- low noise
transistors, <1nV/rt Hz at a few mA.
At these higher currents, I presume even quieter.
cheers
T
2sc3324/a1312 are good for low current applications. But for 10ma to 20ma a better choice is the 2sa1162/2sc2712 as the early effect is weaker at this currents.
The BC327/227 is also much worse than 2sa1162/2712.
One good transistor is also the 2sc3601 but the complementary 2sa1407 is not so good.
In my topology the early effect is not very important but in CEN is very important.
I don´t feel the need to use batteries, as long the power supply are low noise, and the circuit have high PSRR, but if you feel more peace of mind using it, go for it.
But dont use in a power amplifier is no need and a waste of power (think green).
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I can charge the (Hi-discharge Lead Acid rechargeable) batteries for the power amp using photovoltaic panels on the roof.
No frequency converter and all such stuff in between. Much greener than using any mains powered PSU.
🙂
Patrick
No frequency converter and all such stuff in between. Much greener than using any mains powered PSU.
🙂
Patrick
The relatively high Cob of bc227/337 gives stability problems. There are better bjt´s.
Ok, if you going to use it like that.
I am really against using class A power amplifiers,
there are others alternatives like for example class d.
Class D amplifiers are very good nowadays, my biggest priority project right now is finishing my class d amplifier (with my one self oscillating topology of course 🙂)
For everybody understand what is all this talk about the early effect, i post a picture of the Ic-Vce of the par 2sa1407/c3601. As you can see wen the Vce varies there is less variation of Ic in the c3601 than in 2sa1407.
As they say, a picture is worth a thousand words 🙂.
As they say, a picture is worth a thousand words 🙂.
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Shinja have already post a circuit that do that, but increase component count.
You can choose between my topology or the simplicity of CEN, you choose your path.
Like Patrick says i dont see any gain in get rid of the battery in CEN, if you want to gow that way, you will be better serve with my topology.
I'm still waiting for your circuit 🙂.
but if it uses 25mA and you cant switch it off....then you change batteries like a mad man...🙂
I saw the Shinja schematics...An that could be a Way to go....
I don't mind complexity as long as it's not in the signal path...To me the beauty is in the simple circuits, but to make the work well, you may have to do at little housekeeping..🙂
I saw the Shinja schematics...An that could be a Way to go....
I don't mind complexity as long as it's not in the signal path...To me the beauty is in the simple circuits, but to make the work well, you may have to do at little housekeeping..🙂
Hi,
smms: the simple circuit of #301 shows a quite high input impedance of ~12Ohms because of low hfe and increasing values at too low frequencies (due to the 1m-Cap C4). C4 needs to be as small as 1nF or less to keep Zin constant and low into the MHzs.
jauu
Calvin
smms: the simple circuit of #301 shows a quite high input impedance of ~12Ohms because of low hfe and increasing values at too low frequencies (due to the 1m-Cap C4). C4 needs to be as small as 1nF or less to keep Zin constant and low into the MHzs.
jauu
Calvin
Hi Calvin nice to see you.
I have measure 3.8 ohms at 10khz and 12 at 1Mzh , the problem is the parasitic capacitances and low Ft of the MJE15033/32 , one way or another this bjt´s is not a good choice for this circuit i just use it because i already have the models from cordell,
I think the Biss transistors from NXP are much better (high hfe, low capacitances and high Ft)
I don´t see the influence of c4, but i will investigate.
I have measure 3.8 ohms at 10khz and 12 at 1Mzh , the problem is the parasitic capacitances and low Ft of the MJE15033/32 , one way or another this bjt´s is not a good choice for this circuit i just use it because i already have the models from cordell,
I think the Biss transistors from NXP are much better (high hfe, low capacitances and high Ft)
I don´t see the influence of c4, but i will investigate.
the circuit I posted at#286 was reasonably simple but useless!
Indeed floating supply is great, I finally agree.
Indeed floating supply is great, I finally agree.
Are you talking about Early Voltage?
If yes, comparing the datasheets is difficult, but at 300mA the BC337-40 looks better than 2SC2712 at say 100mA
NXP BC337
Toshiba 2SC2712