I need a circuit diagram for a simple waveform monitor??

[Azhar]

I want to try to build a simple waveform monitor, something like an oscilloscope  but without all the fancy function, I just need the circuit to show the waveform by connecting it to a tv or LCD  .. etc
Is there anyone who built something similar? or maybe have a schematics?

[rs20]

I want to try to build a simple waveform monitor, something like an oscilloscope  but without all the fancy function, I just need the circuit to show the waveform by connecting it to a tv or LCD  .. etc
Is there anyone who built something similar? or maybe have a schematics?

What kind of frequencies are you interested in capturing? Do you want to be able to read off voltages, or are you happy with a completely uncalibrated display? Do you want to have a selection of different timebases, or are you happy with just having one fixed timebase?

Driving a TV or LCD is much more challenging than capturing a low-frequency waveform, so that's probably going to be your main concern if you want to build a device that just displays whatever kind of waveform.

I can imagine an interesting yet hacky approach which would be to drive a VGA monitor, and set up an internal sweep that sweeps along with the horizontal scan, and when the sweep matches the input voltage, it makes the current pixel white. That would produce a vertical waveform on the screen. Totally useless, it wouldn't have any sort of trigger functionality, but hey, it's theoretically doable with discrete components only. It could even have 3 channels easily  . I can't emphasise this enough, this is a crazy, curious kind of idea, it would be pretty terrible as an oscilloscope.

[Azhar]

What kind of frequencies are you interested in capturing? Do you want to be able to read off voltages, or are you happy with a completely uncalibrated display? Do you want to have a selection of different timebases, or are you happy with just having one fixed timebase?

Driving a TV or LCD is much more challenging than capturing a low-frequency waveform, so that's probably going to be your main concern if you want to build a device that just displays whatever kind of waveform.

I can imagine an interesting yet hacky approach which would be to drive a VGA monitor, and set up an internal sweep that sweeps along with the horizontal scan, and when the sweep matches the input voltage, it makes the current pixel white. That would produce a vertical waveform on the screen. Totally useless, it wouldn't have any sort of trigger functionality, but hey, it's theoretically doable with discrete components only. It could even have 3 channels easily  . I can't emphasise this enough, this is a crazy, curious kind of idea, it would be pretty terrible as an oscilloscope.

was thinking of something very simple and basic, not voltage read, uncalibrated display.
maybe you are right, it is not easy to build such a circuit, thanks anyways.

[Richard Crowley]

What does "waveform" mean here?  What frequency (or sweep-rate) are you looking for?
Is this for some fixed waveform, or do you want variable sensitivity and/or variable sweep/resolution?
Here in the 21st century, it may be easier to use a microprocessor and make a DIY DSO with a Raspberry Pi or something.

[tautech]

You might find enough to get you started here:
http://homediyelectronics.com/projects/howtomakeafreesoundcardpcoscilloscope/

[Azhar]

You might find enough to get you started here:
http://homediyelectronics.com/projects/howtomakeafreesoundcardpcoscilloscope/

Thanks a lot! that's exactly what I was looking for! A Sound Card Oscilloscope