A year and a half later and everything is ok. I measured it again in winter last year and was fine, nothing changed. Might do another measurement sometimes this year.
I have made some additional modifications to my dienoiser: the stability was very marginal for both HF and VLF.
I have changed the location of the 22nF cap, and added a 56 ohm series resistor. To improve the VLF ringing, I reduced the coupling cap to 10µF. The FR below 100Hz is relatively unimportant anyway.
I have changed the location of the 22nF cap, and added a 56 ohm series resistor. To improve the VLF ringing, I reduced the coupling cap to 10µF. The FR below 100Hz is relatively unimportant anyway.
Hi.
I would like to use this circuit for 9V 500-800mA out. If I reduce R4 to 1k, will that be enough?
Made a board to start testing for an eventually full SMD version but didn't have time to develop it.
Attachments
In its present form, the denoiser is not compatible with high voltages (too much dissipation), nor with topologies more evolved than the basic 317 circuit.
However, the principles could be reused in very different applications.
Could you post the schematic of your Maida implementation? I might be able to see "low hanging fruits", and propose a simple and effective effective solution
However, the principles could be reused in very different applications.
Could you post the schematic of your Maida implementation? I might be able to see "low hanging fruits", and propose a simple and effective effective solution
Apologies for the delay.
It is a version of this here....but use a 7233 series pass triode.
R1 = 200R and R2 = 48K (actually a four by 12k/4wts series string).Set for 300Vdc.
It is a version of this here....but use a 7233 series pass triode.
R1 = 200R and R2 = 48K (actually a four by 12k/4wts series string).Set for 300Vdc.
Thank you! I might at some point. I first need to validate the design. I made a first version PCB but need to assemble and test.
I tried to add one some time ago, you'd have to drop the 263V to some low value, 15V or so, and you'd have around 2.5W (at 10mA) dissipated power in the denoiser resistor.Apologies for the delay.
It is a version of this here....but use a 7233 series pass triode.
R1 = 200R and R2 = 48K (actually a four by 12k/4wts series string).Set for 300Vdc.
I have thought about the HV version.
This is the first draft: it is based on an upside-down configuration, to increase the correction gain without increasing the dissipation. Of course, this requires a phase inversion to keep the FB negative, hence the LTP.
This is the performance of the initial circuit, with the denoiser unconnected:
The triode is a A2293, close to the 7233, and the model is created by @Adrian Immler .
I pruned all the comments and unnecessary bits to make the appearance more legible on the schematic sheet, but I acknowledge the origin and intellectual property.
Now, the situation with the denoiser active:
Clearly, an improvement.
However, the circuit is not optimal due to impedances mismatch.
To address the issue, a buffer stage can be added.
To avoid the extra consumption this would entail, the buffer can be fed from the other arm of the LTP, keeping the total consumption at ~4mA:
All of this looks promising, but it is only a preliminary work, and it has not been optimized or streamlined in any way.
In addition, many elements are lacking, even if the simulation looks alright: there is no frequency compensation, and more importantly, there are no protections. A number of diodes and zeners would be required to avoid frying the circuit the first time it is powered.
I will come up with a resilient, buildable circuit later. The compensation aspect will have to be tested on an actual prototype, because the sim doesn't help in this part
This is the first draft: it is based on an upside-down configuration, to increase the correction gain without increasing the dissipation. Of course, this requires a phase inversion to keep the FB negative, hence the LTP.
This is the performance of the initial circuit, with the denoiser unconnected:
The triode is a A2293, close to the 7233, and the model is created by @Adrian Immler .
I pruned all the comments and unnecessary bits to make the appearance more legible on the schematic sheet, but I acknowledge the origin and intellectual property.
Now, the situation with the denoiser active:
Clearly, an improvement.
However, the circuit is not optimal due to impedances mismatch.
To address the issue, a buffer stage can be added.
To avoid the extra consumption this would entail, the buffer can be fed from the other arm of the LTP, keeping the total consumption at ~4mA:
All of this looks promising, but it is only a preliminary work, and it has not been optimized or streamlined in any way.
In addition, many elements are lacking, even if the simulation looks alright: there is no frequency compensation, and more importantly, there are no protections. A number of diodes and zeners would be required to avoid frying the circuit the first time it is powered.
I will come up with a resilient, buildable circuit later. The compensation aspect will have to be tested on an actual prototype, because the sim doesn't help in this part
This is the ruggedized, buildable version of the simpler, -125dB@100Hz variant:
Tweaking of C1 might be necessary, and it is even possible that the circuit cannot be stabilized: mixing a maida and denoiser might be too much; only an experiment will tell. Fortunately, with a triode as auxiliary device, chances are good since the gain and transconductance are low compared to semiconductors.
Tweaking of C1 might be necessary, and it is even possible that the circuit cannot be stabilized: mixing a maida and denoiser might be too much; only an experiment will tell. Fortunately, with a triode as auxiliary device, chances are good since the gain and transconductance are low compared to semiconductors.