Spikes on Zener Clamp Circuit

[rich]

I am using a zener clamp to regulate a messy signal down to a level
that will cause an interrupt in a microcontroller. The circuit works
fine but I am seeing some troubling spikes on the output, both
negative and positive.
The input signal is a reoccurring ~150Vpp ringing signal.

I would appreciate any ideas....

See details at:

http://members.dsl-only.net/~rsoennichsen/zener_clamp.htm

Rich

 

[Andrew Holme]

I am using a zener clamp to regulate a messy signal down to a level
that will cause an interrupt in a microcontroller. The circuit works
fine but I am seeing some troubling spikes on the output, both
negative and positive.
The input signal is a reoccurring ~150Vpp ringing signal.

I would appreciate any ideas....

See details at:

http://members.dsl-only.net/~rsoennichsen/zener_clamp.htm

Rich

Those spikes look uncorrelated with your CH2 input signal. Do you still get
them even if you touch the CH1 'scope probe to ground at the diode anodes?
In electrically noisy environments, you can pickup huge impulses on a
single-turn loop formed by connecting the probe ground lead to the tip.

You could add a little filtering to your input circuit using series
inductance (e.g. ferrite beads) and/or shunt capacitance.

 

[whit3rd]

I am using a zener clamp to regulate a messy signal down to a level
that will cause an interrupt in a microcontroller. The circuit works
fine but I am seeing some troubling spikes on the output

High slew rate signals might result from inductive coupling of wiring
near the clamp. The Zener clamps the conducted signal, but the
wire in series with that signal can couple, as a transformer winding,
to the input.

 

[BobW]

I am using a zener clamp to regulate a messy signal down to a level
that will cause an interrupt in a microcontroller. The circuit works
fine but I am seeing some troubling spikes on the output, both
negative and positive.
The input signal is a reoccurring ~150Vpp ringing signal.

I would appreciate any ideas....

See details at:

http://members.dsl-only.net/~rsoennichsen/zener_clamp.htm

Rich

What is it you've captured? That signal has a period of 100us (10kHz), but a
standard ringing signal is usually 20Hz.

Bob

 

[rich]

Those spikes look uncorrelated with your CH2 input signal. Do you still get
them even if you touch the CH1 'scope probe to ground at the diode anodes?
In electrically noisy environments, you can pickup huge impulses on a
single-turn loop formed by connecting the probe ground lead to the tip.

You could add a little filtering to your input circuit using series
inductance (e.g. ferrite beads) and/or shunt capacitance.

I think you may be on to something. I will ground the scope probe
right next to the tip and see what it looks like. The ferrites are a
good idea too.

thanks

rich

 

[Jan Panteltje]

I am using a zener clamp to regulate a messy signal down to a level
that will cause an interrupt in a microcontroller. The circuit works
fine but I am seeing some troubling spikes on the output, both
negative and positive.
The input signal is a reoccurring ~150Vpp ringing signal.

I would appreciate any ideas....

See details at:

http://members.dsl-only.net/~rsoennichsen/zener_clamp.htm

Rich

Why use a diode? A zener is a diode the other way around.

 

[Fred Bloggs]

What is it you've captured? That signal has a period of 100us
(10kHz), but a standard ringing signal is usually 20Hz.

Bob

LOL- subtle...

 

[Fred Bloggs]

I am using a zener clamp to regulate a messy signal down to a level
that will cause an interrupt in a microcontroller. The circuit works
fine but I am seeing some troubling spikes on the output, both
negative and positive.
The input signal is a reoccurring ~150Vpp ringing signal.

I would appreciate any ideas....

See details at:

http://members.dsl-only.net/~rsoennichsen/zener_clamp.htm

Is it really necessary to dissipate a full Watt to drive a micropower input?
This circuit has a fairly huge working input range of amplitudes it will
handle at your frequency:
View in a fixed-width font such as Courier.

 

[Fred Bloggs]

View in a fixed-width font such as Courier.

.
.
.
.
. .-------------------> to INT
. |
. |
. |
. | Vdd (5V)
. | D1 D2 |
. sig >-[470k]--+---|>|---+----|<|---'
. |
. |
. [10k]
. |
. D3 | D4
. sig >-------------|<|---+----|>|---.
. com |
. ---
. dgnd
. D1,2,3,4 1N4148
.
.

Scratch the above. It should be:
View in a fixed-width font such as Courier.

 

[Jamie]

I am using a zener clamp to regulate a messy signal down to a level
that will cause an interrupt in a microcontroller. The circuit works
fine but I am seeing some troubling spikes on the output, both
negative and positive.
The input signal is a reoccurring ~150Vpp ringing signal.

I would appreciate any ideas....

See details at:

http://members.dsl-only.net/~rsoennichsen/zener_clamp.htm

Rich

Hmm, I guess my first question would be:
1.
Are you using a 10:1 probe to measure that?

2. Do you have near by R.F. and maybe the diodes or
uC input is rectifying depending on what side you check?

3. Did you account for parasitic conditions with the construction
of the traces, components etc... ?

----------------
P.S.
Zeners are know to be slightly slow. Don't know if this is an
issue on your end but it might be worth looking into?


--
"I'd rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:

SOME PEOPLE ARE LIKE SLINKIES. NOT REALLY GOOD FOR ANYTHING BUT
THEY BRING A SMILE TO YOUR FACE WHEN PUSHED DOWN THE STAIRS.
http://webpages.charter.net/jamie_5"

 

[Joe G \(Home\)]

I am using a zener clamp to regulate a messy signal down to a level
that will cause an interrupt in a microcontroller. The circuit works
fine but I am seeing some troubling spikes on the output, both
negative and positive.
The input signal is a reoccurring ~150Vpp ringing signal.

I would appreciate any ideas....

See details at:

http://members.dsl-only.net/~rsoennichsen/zener_clamp.htm

Rich

How about an analog scope - could the digital sampling be playing tricks?

joe