Hello,
I'm trying to make a speedometer with a Doppler HB100 sensor and an LM358. Currently, I'm reading data at very close distances to the HB100, but as soon as I move away a bit, I lose the signal. Is it correct to use the LM358? Should I use a different circuit or amplifier?
Thank you,
Roger.
Please post a schematic
Your topic has been moved to the Project Guidance category of the forum
Hi, @pericosmith
Have you Googled;
Doppler HB100 arduino
HB100_RADAR.pdf (513.6 KB)
What range are you looking for?
How big a target?
Tom.. 
Hello Tom,
Right now I can only read up to about 30 centimeters. I would like to reach around 5 to 10 meters. I have the 10GHz and 24GHz Doppler sensors, both of which behave similarly, and their theoretical ranges are from 5 to 15 meters.
Thank you.
Hi,
If you read the pdf I posted, it will show you a sample circuit and code that may help.
I agree with @jim-p, not enough gain in your circuit.
Thanks.. Tom... 
You have to develop them
Thank you Tom and Jim. I'm going to try it.
If you are not sure how to do it, you could try putting two or three of the LM358 modules in series.
Connect the output of the first one to the input of the second and so on. Set the gain of the first one to it's max level
I had thought about doing it, but I understand that the first one already amplifies the signal to the maximum using the potentiometer it has, so would the others replicate the same 12V signal? Or not?
This is what I have:
My first attempt was to build below amplifier from antique stuff out of the analog components bin, but that did pick up some noise.
HB100_radar_with_2x8x8_matrixdisplay.pdf (165.8 KB)
The second attempt worked much better and provided me with a wireless radar speed meter.
The trick is that the first stage is a old fashioned BC549, which seems to have a lot less noise than the LM358 that is used for the subsequent amplification stages.
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