Question for Ruud and Ivan

Hi Ivan,
Thank you VERY much. That is praise indeed from you.

Your point about the hold/decay pot is important. I know if the decay time is too short then the speech can sound "bobbly" (for want of a better word). Like packets of speech with a micro "pop" at the beginning of each.

I had a working colleague (a Serbian radio ham) do a quick review and he is also keen on analogue. He knew what speech processing does, but not how you need to adjust it, depending on conditions. That is why I gave audio examples and even related it to a ladies make-up. That and the audio examples made things clear.

I will work on a PCB for that processor shortly, and I will also see if I can steal a few minutes now and again to finish the IRF510 linear amplifier. I have already laid out the board for a 4-phase audio shifter for SSB generation (the 4th method?).

I'll tell you one thing Ivan, it is fantastic that I have now got an oscilloscope, RF and AF generators and spectrum analyser. Those and the GDO / frequency counter mean that I can do almost anything I want, if only I had the time.

The electricians have pulled most of the cables in the house, probably just one last day to work. The painters and decorators have done most of the house, just have to take all the boxes out of my "workshop" so they can finish that next, then I can get my workbench sorted out. Not easy while I am still working, even some weekends (like tomorrow).

Thank you once more for your comments Ivan. Really appreciated.

Have a nice weekend - Harry

Hi Harry,
perfect work as always!
I am glad you stay on simple analog circuits. Many "developers" use a DSP and its behaviour define by software. Very boring practice!!
I have had bad experience with mike signal processing generally. We used unmodified AF signal for all radios and phones as a result. But selecting a quality mike with the proper space characteristic proved to be crucial.
About your construction:
Using a potentiometer to change the hold time (discharging the capacitor in the gate) is IMHO important. Otherwise periodic changes of volume may occur.
Up to now I did not mention anything else.

VBR from Ivan

Hi Ruud and Ivan,

I really respect your knowledge and experience. I have been putting together a new project (two, actually). If you can review the first I would be really grateful.
The URL is http://sm0vpo.altervista.org/1/mic_processor.htm

I will not say anything about it as it should all be stated in the text.

One question, would it be an idea to include the LTspiceXVII project file? The thought is that if anyone wants to modify it then it can be useful.

The other project I am working on is a simple Linear Amplifier. Based on my 10-Watt (15-watt) linear using CB transistors, but this time I got a little surprise. IRF510 will deliver more like 30 Watts, and a pair of them will comfortable deliver 35 Watts at 12 V (50-Watts at 14 Volts). The prototype on the bench was a bit "Heath Robinson" but it was stable. Now completed the PCB but no time to assemble it. Not until the painter, decorator and electricians have finished their jobs.

BR Harry