Timeline for Secondary voltage spike in flyback transformer
Current License: CC BY-SA 4.0
25 events
| when toggle format | what | by | license | comment | |
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| Jul 21 at 20:07 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Jun 20 at 17:08 | answer | added | Math Keeps Me Busy | timeline score: 2 | |
| Dec 25, 2020 at 20:13 | comment | added | Andy aka | Did you sort this out @FarvezFarook - if you did maybe you can leave your own answer explaining the fix/solution? | |
| Dec 18, 2020 at 6:10 | comment | added | Farvez Farook | Yes i did, i have not added that in the schematic | |
| S Dec 18, 2020 at 6:04 | history | bounty ended | CommunityBot | ||
| S Dec 18, 2020 at 6:04 | history | notice removed | CommunityBot | ||
| Dec 17, 2020 at 16:04 | comment | added | Andy aka | Did you use C3 @FarvezFarook | |
| Dec 15, 2020 at 12:12 | comment | added | Andy aka | C3 in the data sheet connected to BP. You don't have a C3. | |
| Dec 15, 2020 at 9:59 | comment | added | Farvez Farook | The diode could be the problem. Due to late turn on of the diode the snubber is not able to supress the leakage inductance induced spike. Are you reffering to the snubber capacitor or bypass capacitor of the ic as C3 | |
| Dec 14, 2020 at 12:28 | comment | added | Andy aka | The 1N4007 diode you have used is not really recommended because of potentially its high reverse recovery time. The data sheet recommends a 1N4937 - try that out. It's potentially a hundred times quicker than the 400x range of diodes. Also, the data sheet shows C3 being present but your circuit does not. Have you fitted this part? | |
| Dec 11, 2020 at 17:39 | comment | added | Bunyamin | I saw this problem at my flyback design. I add a capacitor in parallel to Vin and solved. You had better try this method in my opinion. | |
| Dec 10, 2020 at 9:00 | history | tweeted | twitter.com/StackElectronix/status/1336958883584204802 | ||
| Dec 10, 2020 at 4:41 | comment | added | Damien | Add a bunch of 10uF ceramic caps in parallel to C2. Electrolytic caps have a slow response and inductive effects. | |
| S Dec 10, 2020 at 4:24 | history | bounty started | Farvez Farook | ||
| S Dec 10, 2020 at 4:24 | history | notice added | Farvez Farook | Authoritative reference needed | |
| Dec 8, 2020 at 5:07 | comment | added | Farvez Farook | @Andy sorry i misunderstood your previous method. I did as you suggested i can see a the voltage spike of the wave form on the grounded probe and it is also slighlty leading the the actual output voltage.But the magnitude of the grounded probe is of 20-30 millivolts only.Also the peak of the spike of the output voltage is 14.1V | |
| Dec 7, 2020 at 16:06 | comment | added | glen_geek | You may be exceeding oscilloscope's dynamic range...zero volts is far, far below the screen bottom. Although display says "500mV/div" the means value is 13.2V DC. Try backing-off to a lower scale, and see if the waveshape persists. Or switch to AC coupling to block that large, potentially disturbing 13.2V. | |
| Dec 7, 2020 at 15:25 | comment | added | Andy aka | Were you connecting to 0 volts on the target circuit when you did that i.e. did you simultaneously short the probe to the earth wire whilst the earth wire is connected to 0 volts on the secondary? | |
| Dec 7, 2020 at 15:17 | comment | added | Farvez Farook | I shorted the probe ground and tip as you suggested there is only an steady DC offset voltage of about 10mV. I think the probing is not the issue. | |
| Dec 7, 2020 at 15:11 | comment | added | Andy aka | See this for correct probing to avoid false readings. You can check how good your present probing is by shorting the probe tip to your ground clip and see what the scope voltage looks like. I bet it looks pretty similar to your pictures above. Put some numbers on the spike voltage - do I have to repeat myself???? | |
| Dec 7, 2020 at 15:07 | history | edited | JRE | CC BY-SA 4.0 | added 1 character in body |
| Dec 7, 2020 at 15:05 | history | edited | Farvez Farook | CC BY-SA 4.0 | edited body |
| Dec 7, 2020 at 15:00 | comment | added | Andy aka | How good is your oscilloscope probing method? And, can you put some numbers on the spike you see (presumably the yellow trace where light blue is primary?). Also 200,000 farads is not an acceptable clamp capacitor value. | |
| Dec 7, 2020 at 14:59 | history | edited | JRE | CC BY-SA 4.0 | added 19 characters in body; edited title |
| Dec 7, 2020 at 14:56 | history | asked | Farvez Farook | CC BY-SA 4.0 |