Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Q&A

Post History

77%
+5 −0
Q&A Unexpected impedance spike when paralleling capacitors

I was watching a video from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes: ...

3 answers  ·  posted 2y ago by Elleanor Lopez‭  ·  last activity 2y ago by Andy aka‭

#5: Post edited by user avatar Elleanor Lopez‭ · 2022-06-01T07:18:49Z (over 2 years ago)
  • I was watching a [video](https://youtu.be/BcJ6UdDx1vg?t=1611) from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes:
  • ![Image alt text](https://electrical.codidact.com/uploads/m8XSJk2V8U2fM3Q46NSKtc7V)
  • However, he did not explain why the spike is there. Thinking about it some more, I could not come up with an explanation other than bad test setup. Resistance and inductance go down as more values are added in parallel. Although total capacitance goes up, which would lower the total resonance frequency, 110nF in relation to 10uF cannot cause such a drastic shift.
  • This was his test setup:
  • ![Image alt text](https://electrical.codidact.com/uploads/4Un9mAuiYW6xFzZmxe3xXMQX)
  • To inspect the picture, right click and open in new tab, the scales are then visible. Regardless:
  • The frequency scale is logarithmic, impedance scale is linear. Both graphs have 100kHz-40MHz frequency range, and the spike on the left side is located at 8Mhz point, reaching ~800mOhm impedance.
  • I assume that the solder blobs between capacitors introduced a series inductance that in turn caused the spike in impedance at 8MHz.
  • Could that be the case, or is there something else that could cause the spike?
  • I was watching a [video](https://youtu.be/BcJ6UdDx1vg?t=1611) from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes:
  • ![Image alt text](https://electrical.codidact.com/uploads/m8XSJk2V8U2fM3Q46NSKtc7V)
  • To inspect the picture, right click and open in new tab, the scales are then visible. Regardless:
  • The frequency scale is logarithmic, impedance scale is linear. Both graphs have 100kHz-40MHz frequency range, and the spike on the left side is located at 8Mhz point, reaching ~800mOhm impedance.
  • However, he did not explain why the spike is there. Thinking about it some more, I could not come up with an explanation other than bad test setup. Resistance and inductance go down as more values are added in parallel. Although total capacitance goes up, which would lower the total resonance frequency, 110nF in relation to 10uF cannot cause such a drastic shift.
  • This was his test setup:
  • ![Image alt text](https://electrical.codidact.com/uploads/4Un9mAuiYW6xFzZmxe3xXMQX)
  • I assume that the solder blobs between capacitors introduced a series inductance that in turn caused the spike in impedance at 8MHz.
  • Could that be the case, or is there something else that could cause the spike?
#4: Post edited by user avatar Elleanor Lopez‭ · 2022-06-01T07:18:30Z (over 2 years ago)
Described the axis
  • I was watching a [video](https://youtu.be/BcJ6UdDx1vg?t=1611) from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes:
  • ![Image alt text](https://electrical.codidact.com/uploads/m8XSJk2V8U2fM3Q46NSKtc7V)
  • However, he did not explain why the spike is there. Thinking about it some more, I could not come up with an explanation other than bad test setup. Resistance and inductance go down as more values are added in parallel. Although total capacitance goes up, which would lower the total resonance frequency, 110nF in relation to 10uF cannot cause such a drastic shift.
  • This was his test setup:
  • ![Image alt text](https://electrical.codidact.com/uploads/4Un9mAuiYW6xFzZmxe3xXMQX)
  • I assume that the solder blobs between capacitors introduced a series inductance that in turn caused the spike in impedance at 8MHz.
  • Could that be the case, or is there something else that could cause the spike?
  • I was watching a [video](https://youtu.be/BcJ6UdDx1vg?t=1611) from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes:
  • ![Image alt text](https://electrical.codidact.com/uploads/m8XSJk2V8U2fM3Q46NSKtc7V)
  • However, he did not explain why the spike is there. Thinking about it some more, I could not come up with an explanation other than bad test setup. Resistance and inductance go down as more values are added in parallel. Although total capacitance goes up, which would lower the total resonance frequency, 110nF in relation to 10uF cannot cause such a drastic shift.
  • This was his test setup:
  • ![Image alt text](https://electrical.codidact.com/uploads/4Un9mAuiYW6xFzZmxe3xXMQX)
  • To inspect the picture, right click and open in new tab, the scales are then visible. Regardless:
  • The frequency scale is logarithmic, impedance scale is linear. Both graphs have 100kHz-40MHz frequency range, and the spike on the left side is located at 8Mhz point, reaching ~800mOhm impedance.
  • I assume that the solder blobs between capacitors introduced a series inductance that in turn caused the spike in impedance at 8MHz.
  • Could that be the case, or is there something else that could cause the spike?
#3: Post edited by user avatar Lundin‭ · 2022-06-01T06:46:26Z (over 2 years ago)
#2: Post edited by user avatar Elleanor Lopez‭ · 2022-05-31T08:43:47Z (over 2 years ago)
  • I was watching a [video](https://youtu.be/BcJ6UdDx1vg?t=1611) from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes:
  • ![Image alt text](https://electrical.codidact.com/uploads/m8XSJk2V8U2fM3Q46NSKtc7V)
  • However, he did not explain why the spike is there. Thinking about it some more, I could not come up with an explanation other than bad test setup. Resistance and inductance go down as more values are added in parallel. Although total capacitance goes up, which would lower the total resonance frequency, 110nF in relation to 10uF cannot cause such a drastic shift.
  • This was his test setup:
  • ![Image alt text](https://electrical.codidact.com/uploads/4Un9mAuiYW6xFzZmxe3xXMQX)
  • I assume that the solder blobs between capacitors introduced a series impedance that in turn caused the spike in impedance at 8MHz.
  • Could that be the case, or is there something else that could cause the spike?
  • I was watching a [video](https://youtu.be/BcJ6UdDx1vg?t=1611) from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes:
  • ![Image alt text](https://electrical.codidact.com/uploads/m8XSJk2V8U2fM3Q46NSKtc7V)
  • However, he did not explain why the spike is there. Thinking about it some more, I could not come up with an explanation other than bad test setup. Resistance and inductance go down as more values are added in parallel. Although total capacitance goes up, which would lower the total resonance frequency, 110nF in relation to 10uF cannot cause such a drastic shift.
  • This was his test setup:
  • ![Image alt text](https://electrical.codidact.com/uploads/4Un9mAuiYW6xFzZmxe3xXMQX)
  • I assume that the solder blobs between capacitors introduced a series inductance that in turn caused the spike in impedance at 8MHz.
  • Could that be the case, or is there something else that could cause the spike?
#1: Initial revision by user avatar Elleanor Lopez‭ · 2022-05-31T08:42:40Z (over 2 years ago)
Unexpected impedance spike when paralleling capacitors
I was watching a [video](https://youtu.be/BcJ6UdDx1vg?t=1611) from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes:
![Image alt text](https://electrical.codidact.com/uploads/m8XSJk2V8U2fM3Q46NSKtc7V)

However, he did not explain why the spike is there. Thinking about it some more, I could not come up with an explanation other than bad test setup. Resistance and inductance go down as more values are added in parallel. Although total capacitance goes up, which would lower the total resonance frequency, 110nF in relation to 10uF cannot cause such a drastic shift.

This was his test setup:
![Image alt text](https://electrical.codidact.com/uploads/4Un9mAuiYW6xFzZmxe3xXMQX)

I assume that the solder blobs between capacitors introduced a series impedance that in turn caused the spike in impedance at 8MHz.

Could that be the case, or is there something else that could cause the spike?