1. Home
  2. Electronics Design
  3. positive response from noise input

positive response from noise input

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

Reply to
captoro
Loading thread data ...

Is a glitch different from someone talking?

Reply to
miso

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 to
captoro

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 to
Phil Hobbs

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 to
Fred McKenzie

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.