Next SINUS project??

[sinus trouble]

Finally! I have all the parts to complete the project!

However, I received an Email from CPC that the 1N5346 Zener Diodes expected delivery has been pushed back to December 2023!!

Its not all bad news though! My bench PSU is capable of providing the voltages needed to get it up and running!

I also ordered some 2N3866s to play with!

[sinus trouble]

Sinus - you will have seen my adaptations of the NRG circuit for stereo. It only adds a few extra components to each channel, and you can have a single sidechain for both channels (so that you don't compromise the stereo image). The only minor issue is that you have to match the FET pinch-off voltages, but other than that, it's plain sailing!
Laying out the PCB so that it's just one-sided is tricky, but can be achieved if you're prepared to accept a couple of jumper wires (or "Zero Ohm Resistors" like NRG used to supply in some of the kits).

Cheers Albert! And you are spot on with a number of points!

I get the feeling that i am gonna have to revisit this project at some point?

The layout of this PCB is the most complex design i have attempted to manufacture so far!

I have a rough idea of how it will perform? But i guess the "proof is in the pudding" as they say?

Once i get a feel of how this prototype behaves? Some extra features will certainly follow!

[Albert H]

However, I received an Email from CPC that the 1N5346 Zener Diodes expected delivery has been pushed back to December 2023!!

The 1N5346 is just a 9V1 zener diode. Any 9V1 zener will do the job! In fact, any combination of zener diodes with a chain of ordinary diodes that will give you around 9V1 will do.

[radium98]

nice infos , i would like to see how low volume will be increased and strong one will decrease as an agc .

[sinus trouble]

nice infos , i would like to see how low volume will be increased and strong one will decrease as an agc .

I have now completed the circuit and can confirm that the AGC works!

More of this to come!

[sinus trouble]

So as i mentioned the PCB is now working! Pics below!

[sinus trouble]

20230215_165721.jpg

[sinus trouble]

So i got to test the prototype today!

Everything powered up perfectly! Current consumption was less than 50mA @ 13.8V

I left the 15Khz low pass filter incomplete and run some music through it!

I have to say? This thing sounds PHENOMENAL!!!

Whilst the transition between volume changes were quite slow? I did not detect any "Pumping" or strange instrument sounds!

Anyways i hope to do some further tests by sweeping the band and finalising the LPF!

I made a short video to show operation too!

[sinus trouble]

[radium98]

wonderfull . How did you calibrate that to 0db ?
by the way Sinus i sent you a pm very long time .i want to ask what the big diode is for ?

I bought and did that in 2006 , but it was not good and lost them all , because when we went to another place , everything gone with the wind .

[sinus trouble]

wonderfull . How did you calibrate that to 0db ?
by the way Sinus i sent you a pm very long time .i want to ask what the big diode is for ?

I bought and did that in 2006 , but it was not good and lost them all , because when we went to another place , everything gone with the wind .

Excellent Pics Radium!

I have never seen that version before? The obvious difference is the 15Khz Filter modification! But also a voltage regulator is used too!

With regards to 0db setup, My DJ Mixer has VU display meters which makes the whole process easier!

There are two large diodes in the original design, The first is a simple rectifier diode (Removed from my design) which blows the fuse in the case of DC polarity fault! Nice protection for beginners who may wire up the circuit incorrectly? But not essential!

The second diode (Included in my design) is a 9.1V Zener! This is kind of old fashioned these days, but acts like a typical voltage regulator and sets a 9V DC supply for IC2!

[Albert H]

The 9V1 reference is also providing a stabilised voltage to bias the FET accurately.

[sinus trouble]

The 9V1 reference is also providing a stabilised voltage to bias the FET accurately.

Indeed!

Also provides a 4.5V DC reference for IC1 to allow voltage swing headroom! Via a potential divider!

[radium98]

do you want to deliver it to public in the forum after the final tests.

[sinus trouble]

do you want to deliver it to public in the forum after the final tests.

I will no doubt share everything you need to build this project! I could share it right now, But it is still in the testing phase!

[sinus trouble]

So I have noticed a problem with the design which i thought may be useful to discuss here!

During testing i found the source media volume had to be reduced to an acceptable level!

The source media seemed to be driving the limiter too hard and in turn the limiting was pretty harsh!

Whilst no distortion was present? I decided to see what was going on?

So i applied a 1Khz sine and monitored the input and output on the scope! Here is what i found!

[sinus trouble]

Limiter IN Versus OUT.PNG

[sinus trouble]

Above, We can see the two 1Khz signals!

RED is the input signal @ 1V peak to peak

Green is the output signal @ 16V peak to peak

This explains why the limiter is too loud to feed any sort of exciter! So at first glance, it would seem that the limiter is not functioning?

However this is not the case! The limiter maintains 16V peak to peak output even when the input amplitude is changed!

Infact, I can visually see the output signal correcting itself as changes are applied! (I will try to capture on video)

I believe the problem lies with the final OP AMP gain setting?

Measurements of the low pass section shows "Unity Gain" which is to be expected!

I cannot explain why?? Maybe the TL074CN has better gain over older types?? Maybe the TOKO filter was not Unity Gain?? Maybe the replacement JFET has an effect?? Who knows??

If we look back at the schematic, R11 sets the Gain for the final stage! I have found that reducing the value of this resistor gives much better results!

[LeeCavanagh]

Hi sinus

Could you use a side chain
Does this have a look ahead ?

Don’t ask me how.

Oh, with regards metering, I calibrate stuff using a really large led rack display which was cheap on eBay, I use it to monitor deviation of all the commercial stations to compare, signal1 need one (theirs is shocking)

I also use a 0db 1khz tone, and for multiband I use pink noise to max out the spectrum leds (when I remember),
But remember, I feel dumb when I read everyone else’s expert tech knowledge about components, I really wish I’d bothered to pay attention growing up but I learned to code software and stuff instead for my career.

I will be watching with interest, if I can build the end result then my gran could, although she did pass away so that may be difficult.

[sinus trouble]

Hi sinus

Could you use a side chain
Does this have a look ahead ?

Don’t ask me how.

Oh, with regards metering, I calibrate stuff using a really large led rack display which was cheap on eBay, I use it to monitor deviation of all the commercial stations to compare, signal1 need one (theirs is shocking)

I also use a 0db 1khz tone, and for multiband I use pink noise to max out the spectrum leds (when I remember),
But remember, I feel dumb when I read everyone else’s expert tech knowledge about components, I really wish I’d bothered to pay attention growing up but I learned to code software and stuff instead for my career.

I will be watching with interest, if I can build the end result then my gran could, although she did pass away so that may be difficult.

The thing i love about electronics is that there are often more questions than answers!

The versatility and dynamics allow you to create anything you want! Even if it does not work? You can investigate why that is the case!

Ofcourse there are parameters and component limitations to understand along the way! But you dont have to be an expert to experiment!

Whenever i release a project, I know that tweaks and modifications will follow!