Timeline for High-voltage power source oscillations
Current License: CC BY-SA 4.0
11 events
| when toggle format | what | by | license | comment | |
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| Jan 17, 2023 at 9:13 | comment | added | Chupacabras | I have "inverted" that part around opto and opamp. And that did the trick. I was playing with values of R8 (in my schematic), changed it do 270 ohms, and now the oscillations are gone :) | |
| Jan 14, 2023 at 22:10 | comment | added | Antonio51 | As a result, changing my C1 (integrating capacitor), is now possible (1 pF -> 1000 pF or more). | |
| Jan 14, 2023 at 22:00 | comment | added | Antonio51 | I noted that your circuit was not "stable" with Opto wired as you did ("follower"). I change it to "inverter" and then it was "stable". So, I could add an effective and useful capacitor (my C1) wired with op-amp as an integrator and C7. Note that "rise on" time is not the same as "rise down" timing at output Vo. | |
| Jan 14, 2023 at 21:54 | comment | added | Antonio51 | M2 and Q2 is a "current" limiting circuit. I replaced it by my 10k resistor. Ok, it is or the "same" circuit but I used it for testing the regulator circuitry (right part of the design). As PC817 is not in my "library", I used "equivalent" 4N33 (?) which does not change really the behavior. Compensation is done simply: your R6 x C6 = R7 x C7. C6= ~ 5 pF. As R6= ~100 x R7 then C7 = ~ 100 x C6 = 500 pF. | |
| Jan 14, 2023 at 21:36 | comment | added | Chupacabras | I'm not sure what to take from your simplified circuit. It seems you used completely different opto, and no "main" transistor (M2). I understand you see problem in compensation, but I do not know how to compensate it. | |
| Jan 13, 2023 at 16:41 | history | edited | Antonio51 | CC BY-SA 4.0 |
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| Jan 13, 2023 at 8:24 | history | edited | Antonio51 | CC BY-SA 4.0 |
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| Jan 12, 2023 at 17:23 | history | edited | Antonio51 | CC BY-SA 4.0 |
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| Jan 12, 2023 at 13:13 | comment | added | Chupacabras | I put C7 parallel to R7. Any value higher than 0p makes ripple higher. | |
| Jan 12, 2023 at 13:00 | comment | added | Chupacabras | L1, L2, L3 are just parasitic inductances. | |
| Jan 12, 2023 at 12:53 | history | answered | Antonio51 | CC BY-SA 4.0 |