PWM to analog 10v. What have I done wrong?

[Zero999]

Thank you again Zero! I've had a bit of fun playing with your .asc file. I haven't really used spice successfully before but your file helped me to understand it. I've spend the last few days running various simulations for circuits I use like I'm addicted to a video game. LOL but it's been quite the learning experience. I'm going to give this latest circuit a go. I modeled both and I can see that there is much less ripple on the output of this latest circuit. Thank you so much for your help! You've helped me learn a bunch.

Beware, simulators can lie. Some models aren't 100% accurate, especially things such as the power consumption and output stage of op-amps. It's often very easy to tweak a circuit so it works in the simulator, but fails in real life. It's always a good idea to build a prototype first.

[sofa-king]

Zero999, I just wanted to thank you again for your help! I ended up running into an issue with the last circuit you provided. It worked great but wouldn't go below .25v. My uneducated guess is there was some load causing it not to be able to go to the low rail. None the less, I basically removed some parts and added some jumpers so that it (almost) matched the circuit you gave before the last one and it works 100% perfectly. Let me know if there is some way I can buy you a beer my friend!

[Zero999]

Zero999, I just wanted to thank you again for your help! I ended up running into an issue with the last circuit you provided. It worked great but wouldn't go below .25v. My uneducated guess is there was some load causing it not to be able to go to the low rail. None the less, I basically removed some parts and added some jumpers so that it (almost) matched the circuit you gave before the last one and it works 100% perfectly. Let me know if there is some way I can buy you a beer my friend!

The LM358 can't really sink any current and stay near the negative rail, but none of the circuits I posted get the op-amp to sink and current, unless a load is connected between the output and +V

In what way did the circuit you build differ with the schematic I posted?

[sofa-king]

The op-amp I used was a MC33202DR2G.

From the last schematic you provided, I basically jumpered R1 and R2 and removed C1 and C2. So that the second amp is just a follower. It's exceeded my expectations. Though I figure I'd add in the 2nd and 3rd order filters in the next attempt.

[Zero999]

The op-amp I used was a MC33202DR2G.

From the last schematic you provided, I basically jumpered R1 and R2 and removed C1 and C2. So that the second amp is just a follower. It's exceeded my expectations. Though I figure I'd add in the 2nd and 3rd order filters in the next attempt.

The filter was probably oscillating. Fortunately a simple passive RC filter was good enough, in this case.