Reply by Fred McKenzie●December 23, 20142014-12-23
In article <5f2d847a-2a0a-4a06-8782-fb33ecc103fa@googlegroups.com>,
captoro <lerameur101@gmail.com> wrote:
> Hello All,
> Making a project where I need to turn on a led when there is a glitch on my
> RF C.B.
> Most often the noise I receive is on the negative side (-100mv to -2v) as
> seen on the oscilloscope. I am using an opamp to amplify the voltage to
> usable level. What I need to do is to invert the negative noise so I get the
> positive and negative voltage so I do do not 'miss' any spikes.
> I only use a 9v battery to power the opamp. I do not have a negative supply.
> Can someone give me an idea or direction to get what I am seeking
Ken-
Consider a peak-to-peak detector circuit. (This has the same
configuration as a voltage doubler circuit.) Series capacitor feeds the
junction of two stacked diodes. Output of top diode has a capacitor to
ground. Choice of capacitors and load resistance determines the decay
time of the output pulse.
One problem may be the forward bias voltage of the diodes. Germanium is
lower than silicon, schotky may be better, but may still not be low
enough for the -100mv signal. To get around the single supply, you
might AC couple to an Op Amp input, and put the detector circuit on its
output.
Fred
Reply by Phil Hobbs●December 23, 20142014-12-23
On 12/23/2014 09:10 AM, captoro wrote:
> On Tuesday, 23 December 2014 03:38:55 UTC-5, miso wrote:
>> captoro wrote:
>>
>>> Hello All, Making a project where I need to turn on a led when
>>> there is a glitch on my RF C.B. Most often the noise I receive is
>>> on the negative side (-100mv to -2v) as seen on the oscilloscope.
>>> I am using an opamp to amplify the voltage to usable level. What
>>> I need to do is to invert the negative noise so I get the
>>> positive and negative voltage so I do do not 'miss' any spikes. I
>>> only use a 9v battery to power the opamp. I do not have a
>>> negative supply. Can someone give me an idea or direction to get
>>> what I am seeking
>>>
>>> regards, Ken
>>
>> Is a glitch different from someone talking?
>
> Just a push on the CB will create a packet of noise, thats all I
> need. The problem is , most of these packets are below zero !
>
> K
>
AC couple it into a window comparator. Then you don't care about
the polarity.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
Reply by captoro●December 23, 20142014-12-23
On Tuesday, 23 December 2014 03:38:55 UTC-5, miso wrote:
> captoro wrote:
>
> > Hello All,
> > Making a project where I need to turn on a led when there is a glitch on
> > my RF C.B. Most often the noise I receive is on the negative side (-100mv
> > to -2v) as seen on the oscilloscope. I am using an opamp to amplify the
> > voltage to usable level. What I need to do is to invert the negative noise
> > so I get the positive and negative voltage so I do do not 'miss' any
> > spikes. I only use a 9v battery to power the opamp. I do not have a
> > negative supply. Can someone give me an idea or direction to get what I am
> > seeking
> >
> > regards,
> > Ken
>
> Is a glitch different from someone talking?
Just a push on the CB will create a packet of noise, thats all I need. The problem is , most of these packets are below zero !
K
Reply by miso●December 23, 20142014-12-23
captoro wrote:
> Hello All,
> Making a project where I need to turn on a led when there is a glitch on
> my RF C.B. Most often the noise I receive is on the negative side (-100mv
> to -2v) as seen on the oscilloscope. I am using an opamp to amplify the
> voltage to usable level. What I need to do is to invert the negative noise
> so I get the positive and negative voltage so I do do not 'miss' any
> spikes. I only use a 9v battery to power the opamp. I do not have a
> negative supply. Can someone give me an idea or direction to get what I am
> seeking
>
> regards,
> Ken
Is a glitch different from someone talking?
Reply by captoro●December 22, 20142014-12-22
Hello All,
Making a project where I need to turn on a led when there is a glitch on my=
RF C.B.
Most often the noise I receive is on the negative side (-100mv to -2v) as s=
een on the oscilloscope. I am using an opamp to amplify the voltage to usab=
le level. What I need to do is to invert the negative noise so I get the po=
sitive and negative voltage so I do do not 'miss' any spikes.
I only use a 9v battery to power the opamp. I do not have a negative supply=
. Can someone give me an idea or direction to get what I am seeking
regards,
Ken