♫♪ My little cheap Circlophone© ♫♪

[danielwritesbac]

Okay, howabout this?

[keantoken]

That's pretty close. Ugly, but that's hat it takes right?

If you build it you may discover it's not needed. But it most likely is.

[terranigma]

Originally Posted by danielwritesbac

Okay, howabout this?

Adding a parallel C-R circuit at NFB for avoiding cap at negative input doesn't seem to me a relevant way for abide purpose. I may be wrong but I actually prefer keep simple as much as possible NFB.

[keantoken]

I as sorta thinking the same thing. You trade an electrolytic for a film. It may be ugly, but maybe it's orth it?

[terranigma]

I also wonder why we shouldn't re-adjust compensation values of original Circlophone respecting new buffer/input implementation. Is it possible to adjust compensations for getting any advantage in terms of output device variety, flexibility, etc?

[keantoken]

In theory, yes. Dan has come up ith some ne compensation schemes and I have made improvements to the servo compensation. But this is all in simulation. Until someone ith a good signal generator and RF skill builds it, e ill never kno.

[danielwritesbac]

Originally Posted by terranigma

Adding a parallel C-R circuit at NFB for avoiding cap at negative input doesn't seem to me a relevant way for abide purpose. I may be wrong but I actually prefer keep simple as much as possible NFB.

Originally Posted by keantoken

I as sorta thinking the same thing. You trade an electrolytic for a film. It may be ugly, but maybe it's orth it?

If I put 10k parallel to the NFB cap it wouldn't have equalized the load on both transistor bases, right?

[keantoken]

It ould be half-equalized. You ould need to make this resistor at least 100k, and then there ould be no point.

[danielwritesbac]

If we're stuck with the input circuit, I can simply return the NFB cap and leave the trimmer on the schematic; however, there's a lot that doesn't do.

Originally Posted by terranigma

I also wonder why we shouldn't re-adjust compensation values of original Circlophone respecting new buffer/input implementation. Is it possible to adjust compensations for getting any advantage in terms of output device variety, flexibility, etc?

Well, yes. That's the step out after this one. I'd like to do that without adding a lot more transistors.

[danielwritesbac]

Okay, NFB cap has returned and the protection diodes have increased to 1v, which may or may not give enough tolerance to avoid offset bounce. The static protected BAT86 are unlikely to misfire, but I have a question: Are the BAT86 durable enough for this or do I need a pair of FR/BY or similar fast silicon to get the 1v figure?

The resulting schematic is much simplified. If the input circuit passes your inspection, then I can begin work on minor compensation adjustments for phase linear up to 1.5mhz, without further increasing the transistor count. To make this sync up, I'll have to put MJ15003G or similar speed output, devices in the simulator, and then compensation adjustments, can then be quite mild, without the complexity we saw earlier. I'm trying for minimal modifications this time. But, first, an input. . . (see attachment). Is this okay?