Electronics Geniuses only...

[bloodline]

I've been playing with this (http://www.falstad.com/circuit/) little Java app for a few days now, but I can't seem to get my designs to match the  behaviour I'm expecting... can anyone confirm that this program is giving accurate results...?

[bloodline]

metalman wrote:
Seems accurate.

What specific circuit are you questioning?

I was trying to make a low pass filter, that can average out a Pulse Density Modulation signal... to make a crude digital to analogue converter. I wanted to prototype it in software before I bought the components I need.

[bloodline]

Speelgoedmannetje wrote:

bloodline wrote:
I was trying to make a low pass filter

Not that I'm an electro genius, but I rather think that's quite a strange low pass filter.
Normally, a low pass filter is a capacitor serially connected to the thing you want to connect to the filter, and a resistor parallel connected to that.
And a high pass filter is a resistor serially connected to it and a capacitor parallel connected.
And eh, (or it might be vice versa)
-edit- Well, I think I saw it wrong

You are right (for a passive LP Filter), but the scope is not giving me the results I expect...

[bloodline]

Speelgoedmannetje wrote:
I used "crocodile clips" a couple of years ago to experiment with such, maybe you can download an evaluation version of that somewhere to check...
(I'm not going to calculate to check for errors in this whole thing atm)

That's a good idea, I hadn't though to compare the Falstad program with another!

[bloodline]

Karlos wrote:

bloodline wrote:

metalman wrote:
Seems accurate.

What specific circuit are you questioning?

I was trying to make a low pass filter, that can average out a Pulse Density Modulation signal... to make a crude digital to analogue converter. I wanted to prototype it in software before I bought the components I need.

You can buy loads of types of A/D converters with all the antialiasing filters etc you could ever want. The IC section of the maplin catalouge alone has loads of them :-D

Yeah, and I've used them before... back when I used to play with electronics as a kid.

But I was just playing with the idea of building everything from scratch rather than buying little "Black Boxes" and chaining them together.