Updated SSI2130 VCO Datasheet available...

[neil.johnson]

Here the phase relationships as I understand it (bottom for tri core)

Datasheet Figure 2 shows the actual relationships between the various waveforms.

Neil

[lemberski]

Thanks, had a peek on the updated datasheet last week. Scratching my head about fig. 10 (expo conv.), that needs a slow (re)read in order to get it. Thanks again for your effort, it's a dream of a datasheet!

[neil.johnson]

Thanks, had a peek on the updated datasheet last week. Scratching my head about fig. 10 (expo conv.), that needs a slow (re)read in order to get it. Thanks again for your effort, it's a dream of a datasheet!

Thanks
I think I went through about 20+ pages of A4 notes to get to understand it enough to describe it!

Cheers
Neil

[Ayeh]

Thank you for all your help, Neil,
I have a question regarding the SSI2130 FMTZ following the datasheet example: feeding sinewave and increasing the amplitude of the modulator I can see and hear when the sine reaches 2.5V "suddenly" through-zero FM happens it's not something progressive, is there a way to be more smooth and subtle in the modulation, I wan to use an attenuator in the input and slowly increase the modulator and the TZFM want it to be progressive, not like and instant switch when reaches 2.5V.
In the first video shows the SSI2130 slowly increasing the modulator.
In the second video I'm using the EN129 TZFM I did the same and it seems to react more smoothly from the beginning as soon as I´m increasing the amplitude of the modulator. Somehow it sounds rounder.





Thanks.

[neil.johnson]

I'll try recreate your test. What were the carrier and modulation frequencies?

Neil

[devinw1]

From the look of your first video, it looks very much like you are not modulating the signal at all (it wiggles ever so slightly for some reason but sounds dead even on pitch)... until the first zero crossing is detected.. You're just hearing when you cross zero and then it starts triggering reversals (like a sync would) but no modulation. Sure seems like that's exactly what's up. Also, Pause the video and see your wave shapes are hard reversals, not the typical "U" shape TZFM reversals under modulation.

[neil.johnson]

Yes it does look a bit wrong. Perhaps Ayeh could provide the schematic of the actual circuit that was built? Especially the pins on the SSI2130 that were used??

Neil

[Ayeh]

From the look of your first video, it looks very much like you are not modulating the signal at all (it wiggles ever so slightly for some reason but sounds dead even on pitch)... until the first zero crossing is detected.. You're just hearing when you cross zero and then it starts triggering reversals (like a sync would) but no modulation. Sure seems like that's exactly what's up. Also, Pause the video and see your wave shapes are hard reversals, not the typical "U" shape TZFM reversals under modulation.

Yes I totally agree it doesn't sound like a blending waveform but more like a hard sync

[Ayeh]

Yes it does look a bit wrong. Perhaps Ayeh could provide the schematic of the actual circuit that was built? Especially the pins on the SSI2130 that were used??

Neil

Everything else from the circuit is working as expected from the datasheet, here is a pic from the FMTZ part of the schematic

I´m just patching from the circuit the sine out and feeding to the FMTZ a 5vpp sine wave with external attenuation before

Thank you

[neil.johnson]

Hmmm... I've just tested this on the SSI2130 test board and it all looks fine, behaving similar to the EN129 circuit. Have you checked for shorts between pin 18 and either pin 17 or 19?

Neil

[Ayeh]

I´ve tested those pins and there are not shorts :( you can see in the pic below, is strange since everything else works as expected.
I guess I will need to solder a new PCB.
however is good to know you don´t have the same behavior as I
thank you for testing

[neil.johnson]

Can you put scope probes on pin 18 and on IC8B pin 7?

[Ayeh]

ok,
the first pic is pin7 IC7
the second pic is pin7 IC8B
the third pic is pin1 IC8A

[neil.johnson]

"the second pic is pin7 IC8B" -- looks wrong. I would look around there.

Neil

[Ayeh]

"the second pic is pin7 IC8B" -- looks wrong. I would look around there.

Neil

I found the problem! now is working

Thank you for your help!

[neil.johnson]

Yay! What was it?

Neil

[Ayeh]

I think, -12V wasn´t feeding correctly to IC8 I just reflowed all that area

[neil.johnson]

First things to always check are "CRAP"...
Clocks
Reset
and
Power



Neil

[Ayeh]

hahahah well noted!

Thanks!

[lickspittle]

Ayeh, can you put up another quick demo? I'd love to hear it working.

[bence]

Hello all!
I have some questions regarding the pwm comparator inputs:
What is the voltage handling range, should the inputs really stay between 0...2.5V as written in the datasheet?

The example hints that the 0...2.5V can be exceeded slightly, but it would be good to know the internal clamping levels and current capability - if there is any. Is it enough to protect the cv input with a series resistor (say 10k), and maybe a low voltage zener (~3v)?

I'd like to put a simple cv mixer before the pwm comparator and be able to overmodulate but would also like to avoid using active clamps if not absolutely necessary.

Thanks:)

[neil.johnson]

You definitely want to keep the pins within the supply voltage rails. I would aim to keep within +/- 5V to be on the safe side.
I'll find out the definitive answer!

Neil

[Ayeh]

Ayeh, can you put up another quick demo? I'd love to hear it working.

Sure here it is

[neil.johnson]

I have some questions regarding the pwm comparator inputs:
What is the voltage handling range, should the inputs really stay between 0...2.5V as written in the datasheet?

Ok, so best to keep them within the range of the power rails to the SSI2130. So best to add some clamps to limit the range.
Just follow the golden rule: sanitize your inputs

Neil

[bence]

I have some questions regarding the pwm comparator inputs:
What is the voltage handling range, should the inputs really stay between 0...2.5V as written in the datasheet?

Ok, so best to keep them within the range of the power rails to the SSI2130. So best to add some clamps to limit the range.
Just follow the golden rule: sanitize your inputs

Neil

hey!
thanks a lot, i was hoping for this answer

cheers!