Converting an Arduino PWM Output to a DAC Output 

You are welcome!

Yes you are correct, great catch!

@@ForceTronics I have made that one off error sooooo many times. I am not sure I will ever stop making the error completly LOL.

no, it's not. it's just the part of the code which generates a 50% PWM wave on the true PWM pin as shown by him on the oscilloscope the first time. you can delete all code related to pin 10 and the sine wave would still be generated on pin 4

EDIT: Know I know lmao

What you see in the video is what I used. If I recall ecg signals are fairly precise and low amplitude. I would not recommend using a PWM signal. I would recommend using a dedicated DAC I that is 14 but or better. If you need it to be low amplitude you probably need some type of divider circuit

انا بعرف كتب و احصل ع PWM

Hello, I am glad you like the video. You are asking about inverter design and that is an area I don't have direct experience with so I am not the right person to give a DC to AC inverter tutorial.

With this example circuit you should get a DC level with a low amplitude sinewave. The frequency of sinewave will match that of PWM signal. The phases of the signal should be about the same, but depends on specs of op amp you use

No dac's are low power devices and would not have enough current to drive a waveform through a load with that little resistance. You would need an amplifier between the dac and the low impedance load. If you're trying to drive a stepper motor you should look at an h bridge circuit not a dac.

What amplifier do you recommend between the dac and the low impedance load?

I don't have amplifier model numbers or specs memorized so you will need to do the research

thank you. I would be happy if you make such a clip in the future. the idea is to be able to listen to the signal from the dac in the speaker, but it should be the same signal and not distorted. I tried with lm386, with a transistor and I didn't succeed ....

Yes that is what a DAC is used for, vary a voltage level. Note that DACs are low current devices so they are meant to control high impedance devices.

Yeah sure. Just make the measurement after the filtering

@@ForceTronics thank you for answer man,i got it..

Two approaches comes to mind. You could use the method presented in this video but you would need to find a microcontroller or other IC that can generate a differential (positive and negative) PWM signal. You would then need to pass it through an active filter with an op amp that has a negative and positive power supply. Note that the filter needs to be designed to allow the frequency of the sinewave to pass but attenuates the frequency elements of the PWM signal. Or you can buy an off the shelf DAC chip with a differential output. Note that such a DAC IC will also require a negative and positive power supply.

@@ForceTronics thanks so much for the detailed reply! If I was to find an off the shelf differential DAC IC, but the only had one main power supply, what would be the easiest method to convert/split this into seperate positive and negative rails to use?

Here is a link that might help: www.newelectronics.co.uk/electronics-technology/the-best-way-to-generate-a-negative-voltage-for-your-system/167618/

You are asking about inverter design and that is an area I don't have direct experience with so I am not the right person to give a DC to AC inverter tutorial.

You can use a simple passive RC filter but they suck for two reasons. First they have a gradual rolloff so your AC ripple on the resulting DC level will be larger in amplitude. Active filters have less loss or the op amp compensates for loss so the resulting DC signal better matches the PWM value.

I have the same problem