Question about PT2399

[chenron7]

hello Im trying to understand how the pt2399 works, can anyone help me ?
attached: picture of pt2399 and application

[mth5044]

Perhaps Merlin's datasheet will help you?

http://www.valvewizard.co.uk/PT2399_Data_Notes.pdf

[chenron7]

Ill be more specific:
1. mod + demod : cant understand whats the purpose of this part.
2. there's an op amp that dont act like low pass (the one that goes into Din)- cant understand his purpose to.
3. I don't understand how these are low pass filters - cant analyse this circuit.

[Vlad Koen]

This is old type 1-bit delta modulation)) very simple and too annoying. For modern circuit it can be used as guitar - reverb; low bandpass ( approximately 4000 hz)
But it is very cheap one.

[chenron7]

still don't understand how the DEM and the MOD works and what is the purpose of each one of them.

[ElectricDruid]

still don't understand how the DEM and the MOD works and what is the purpose of each one of them.

The "MOD" MODulator converts the audio into a 1-bit bitstream, which is then clocked into the RAM. At the other end it is clocked out again and the "DEM" DEModulator turns it back into something vaguely resembling what went in. Look up "Delta modulator" and "1-bit audio bitstream" for some ideas.

The rest is details which I don't understand either because Princeton Technology won't tell us!

T.

[Vlad Koen]

good article about items:
https://en.wikipedia.org/wiki/Delta_modulation

That is it old shematic :