... but the circlotron output stage on passdiy has no gain. Do I understand it correct:
If you use fets, use the circlotron as follower. If you could use semisouth devices, go for voltage amplification in the circlotron...
Regs, Dirk
P.S.: Is there any special reason, that the circlotron was historically only used for current amplification???
If you use fets, use the circlotron as follower. If you could use semisouth devices, go for voltage amplification in the circlotron...
Regs, Dirk
P.S.: Is there any special reason, that the circlotron was historically only used for current amplification???
The Circlotron on the right has a gain of ~µ. You can use transistors with the appropriate bias arrangements:
http://www.tubecad.com/august99/page2.html
If you reconnect the secondaries to the opposite sides of the load, the gain will be ~1.
The first circlotron here (output stage) has a gain of ~2:
http://www.tubecad.com/august99/page3.html
http://www.tubecad.com/august99/page2.html
If you reconnect the secondaries to the opposite sides of the load, the gain will be ~1.
The first circlotron here (output stage) has a gain of ~2:
http://www.tubecad.com/august99/page3.html
Ok, if I understand it properly: The transformer coupled circlotron has a mu amplification. In case of symmetrical ground reference, it would be 1. But this is the only feasible design, otherwise - how could we drive it???
The transformer (secondaries) here is a concept (and a very good design idea).
It is used to model how to apply the input voltage to each FET (I will speak of FETs now). So, if we connect each secondary:
Between gate and source - gain=Gm×Rl
Between gate and the other side of the load (connected to the OTHER source) - gain=1
Between gate and ground - gain=2. In this last case you can feed circlotron from
differential/balanced stage without signal visual connection to ground. The circlotron stage will be referenced to the ground by two resistors divider in parallel with load. And these two resistors can be connected to any voltage to provide the required bias for the output transistors.
The secondary windings can be replaced by resistors fed by current to produce
voltage drop, like in this example:
http://www.ne.jp/asahi/evo/amp/CSPP/2SJ18.htm
There are plenty of possibilities in designing circlotron amplifiers.
It is used to model how to apply the input voltage to each FET (I will speak of FETs now). So, if we connect each secondary:
Between gate and source - gain=Gm×Rl
Between gate and the other side of the load (connected to the OTHER source) - gain=1
Between gate and ground - gain=2. In this last case you can feed circlotron from
differential/balanced stage without signal visual connection to ground. The circlotron stage will be referenced to the ground by two resistors divider in parallel with load. And these two resistors can be connected to any voltage to provide the required bias for the output transistors.
The secondary windings can be replaced by resistors fed by current to produce
voltage drop, like in this example:
http://www.ne.jp/asahi/evo/amp/CSPP/2SJ18.htm
There are plenty of possibilities in designing circlotron amplifiers.
Can you post a schematic without transformer and without ground reference problem that gives a mu amplification?
Sorry for beeing quite unexperienced...
Sorry for beeing quite unexperienced...
HV, You might look at The Amazing Circlotron on the Passdiy web page. That amp is
an example where the output is taken from the drains of the mosfets so it has voltage
gain. There is no reason tubes couldn't be used like this but rember the output impedience will be a lot higher.
an example where the output is taken from the drains of the mosfets so it has voltage
gain. There is no reason tubes couldn't be used like this but rember the output impedience will be a lot higher.
Hi woody, the pass ciclotron gets the voltage gain from the input fets, not from the output devices.
@stephenoh: could you explain the japanese circuit to me???
Regs, Dirk
@stephenoh: could you explain the japanese circuit to me???
Regs, Dirk
It gets gain from both. All the FETs are operated common-
source mode, in which there is both voltage and current
gain.
😎
source mode, in which there is both voltage and current
gain.
😎
Well, Dirk, you are not the only one, who is trying to learn the circlotron specifics.
Since you are asking about µ-level gain, the example in post 145 is exactly what
we are talking here:
Signal current from 2SK215 going through 10K produces voltage drop on this resistor,
which is applied (via bias battery V1, V4) between the gate and source of each SIT -
this is COMMON SOURCE connection and the gain is the highest possible (for 2SJ18 µ~5).
Another example is SEPP stage:
http://www.amplimos.it/images/VFET_2SK82_AMP_Schematic020908A3_2.gif
Voltage, developed on 3.3K, is applied via the source followers Tr16, Tr17
between the gate and source of each 2SK82 - again COMMON SOURCE connection and the gain is highest possible (for 2SK82 µ~4).
In each case the signal current into corresponding resistor is coming from the stage
with a reasonably high output impedance.
Do not take this as an endorsement/approval of each design. Each of them may require
some "polishing". But they are good examples of how to read or design circlotron
stage.
Since you are asking about µ-level gain, the example in post 145 is exactly what
we are talking here:
Signal current from 2SK215 going through 10K produces voltage drop on this resistor,
which is applied (via bias battery V1, V4) between the gate and source of each SIT -
this is COMMON SOURCE connection and the gain is the highest possible (for 2SJ18 µ~5).
Another example is SEPP stage:
http://www.amplimos.it/images/VFET_2SK82_AMP_Schematic020908A3_2.gif
Voltage, developed on 3.3K, is applied via the source followers Tr16, Tr17
between the gate and source of each 2SK82 - again COMMON SOURCE connection and the gain is highest possible (for 2SK82 µ~4).
In each case the signal current into corresponding resistor is coming from the stage
with a reasonably high output impedance.
Do not take this as an endorsement/approval of each design. Each of them may require
some "polishing". But they are good examples of how to read or design circlotron
stage.
The way to understand a circlotron is to meditate on it until
you reach enlightenment. When you understand the
circlotron you can move on to quantum mechanics.
😎
not kidding.
you reach enlightenment. When you understand the
circlotron you can move on to quantum mechanics.
😎
not kidding.
If you reach enlightenment after meditating on quantum mechanics, i'd imagine you'd be the one to tell us what's next 😀
Thank you, Sensei. That's encouraging. I was getting a complex.
May I license the T-shirt rights for that quote? It's my new all time favorite. 🙂
The circlotron is indeed a very nice application of analog electronics, but how good is it at replicating our music. It does fit the simple is better category. Is it particularly effecient?
Tad
Tad
Hay isn't this a J2 discussion thread how did it change to talking about ciclotrons?
Yes I am guilty of it to but shouldn't we keep to the original topic?
Yes I am guilty of it to but shouldn't we keep to the original topic?
