Yes, there are digital glitch filters that will remove noise glitches and clean up a noisy digital signal.

Check this:
https://en.wikipedia.org/wiki/Glitch_removal

 

I'm only 15 so I don't have a job. I have $40 to my name lol. What's the cheapest scope I can get?

I've been using an app on my tablet but I don't think it's very accurate.

You need to find a maker space. They have all kinds of cool stuff you can use or borrow. I was 12 when I built my first 40M CW transmitter.

 

What's wrong with using something like this:

https://www.maximintegrated.com/en/...ters/digital-to-analog-converters/MX7248.html

It's about $8 in singles and contains, on chip, nearly everything you need -- including a voltage reference and output buffer.

The days of rolling your own high quality DACs/ADCs are long past, unless you are doing it as part of a learning experience.

I was planning on using an IC, but if all the IC is is a tiny resistor ladder, the inconsistent digital signal will still cause an inconsistent analog output , right? Unless the chip is designed to even out the signal, I'll have the same problem using an IC as if I built a discrete DAC.

Because of noise, digital "high" signals jitter, what should always be exactly 5 volts, jumps around near 5 volts; 4.82, 5.3, 5.22, 4.9. Constantly jittery, never a constant signal.

Like someone said, that's fine for digital logic, but not for analog waveform generation. If you're sending a jumpy digital signal in, you'll get a jumpy analog signal out, it's totally GIGO!

 

Yes, there are digital glitch filters that will remove noise glitches and clean up a noisy digital signal.

Check this:
https://en.wikipedia.org/wiki/Glitch_removal

This could be what I need, unless this type of thing is built into DAC chips.

 

I was planning on using an IC, but if all the IC is is a tiny resistor ladder, the inconsistent digital signal will still cause an inconsistent analog output , right? Unless the chip is designed to even out the signal, I'll have the same problem using an IC as if I built a discrete DAC.

Because of noise, digital "high" signals jitter, what should always be exactly 5 volts, jumps around near 5 volts; 4.82, 5.3, 5.22, 4.9. Constantly jittery, never a constant signal.

Like someone said, that's fine for digital logic, but not for analog waveform generation. If you're sending a jumpy digital signal in, you'll get a jumpy analog signal out, it's totally GIGO!

No. Your digital lines encode, digitally, the desired analog value.

This digital code drives switches that switch in/out parts of the ladder depending on code.

The reference decides what the actual magnitude of the analog output is going to be for each code, and also determines a great deal of the noise performance.

Finally, the output buffer insures a precise output regardless of load characteristics.

 

Anti-glitch filters:

http://digital.ni.com/public.nsf/allkb/09A669242FC5645286256D890081EC12

 

This digital code drives switches that switch in/out parts of the ladder depending on code.

Oh, I see. In that case, have any recommendations for 5 bit DACs?

 

Oh, I see. In that case, have any recommendations for 5 bit DACs?

I already provided you with a reasonably inexpensive candidate. It is 12 bits. You just set the extra seven low-order bits to zero.

I chose it because it already contains a reference and output buffer.

 

I want to send an oscillating signal out the joystick port of my Commodore 64, by writing 0 and 1 to the bits in the register that corresponds with the port. The problem is that the port is a little noisy, so it doesn't sound that great.

Is this what you are actually trying to do or is this just an example for the purpose of discussion.

The port is not noisy. It is sending 0s and 1s and does so quite well.
Of course, the sound is going to be lousy. That is because you are sending a digital signal and the loudspeaker wants an analog signal.
That is how a Class-D power amplifier works and they work very well. You just have to learn how to do it properly.

 

Is this what you are actually trying to do or is this just an example for the purpose of discussion.

It was just an example really, and in this case the noise must've just been my circuit or the oscilloscope app I was using, like I said it isn't very accurate. But there's always going to be some noise.

 

It was just an example really, and in this case the noise must've just been my circuit or the oscilloscope app I was using, like I said it isn't very accurate. But there's always going to be some noise.

Can you give us a specific problem that you are working on rather than just general discussion?

 

Can you give us a specific problem that you are working on rather than just general discussion?

Well, I'm just experimenting with stuff right now, trying to make different waveforms and sounds. I'm just messing around, I don't really have a real project in mind. It looks like I need a DAC to get anywhere with this stuff so I think I'll get one.

Anyway, thanks for the help. I'm going to see about finding a place with an oscilloscope.

 

Well, I'm just experimenting with stuff right now, trying to make different waveforms and sounds. I'm just messing around, I don't really have a real project in mind. It looks like I need a DAC to get anywhere with this stuff so I think I'll get one.

Anyway, thanks for the help. I'm going to see about finding a place with an oscilloscope.

Not a problem.
You don't have to find an oscilloscope to have fun with light and sound.

Here is a short list of items to get:

(2) 555 timer chip (NE555, LM555, LMC555, TLC555)
(10) assortment of resistors (100-1MΩ)
(10) assortment of capacitors (0.001 - 10μF)
(1) variable resistor (10k-100kΩ)
(1) 9V battery
(1) 9V battery clip
(5) LEDs
(1) loudspeaker
(1) solderless breadboard
bundle of hookup wire (or male-male jumpers)

There are lots of websites with fun 555-timer circuits you can build.
Here is the first hit from Google:

http://www.555-timer-circuits.com/

Have fun and good luck!

 

Many Active Filter's Are Designed Using A General Purpose Operational Amplifier. IF you know what Frequencies and Levels your Noise consists of, you have solved the most difficult part of Noise Reduction. You may then design a simple Low Pass, High pass, Bandstop, or Band Pass Filter.