Digital radar speedometer

[Ted1]

I

 

[ante1]

Hi Ted,

Interesting circuit this one. I have tried to analyse it but couldn

 

[Ted1]

There shoud be someone out there who knows how the timebase are calculated . I urgently require these theory analysis for my project.

 

[MP1]

Just a quick look, but it looks like two sets of 7404 setup as oscillators. One is flashing the laser diode and the other is "anded" with the return signal, then this is processed and a calculation is made of the difference.
Not much, but hope it helps.

MP

 

[ante1]

MP,

Thanks for your input I see what you mean. Could this be an accurate instrument do you think?

Ante :

 

[Ted1]

Thanks for your input, do you know of the formula to calculate the frequency , when using two not gates.

 

[MP1]

ante,
Radar is a bit out of my area of knowledge, but it seems like any reflection of the laser would cause you to lose accuracy when the signal bounces back. From the description in the project, it will only be accurate if you are directly in front of the object and it is moving toward you.
Ted,
I found an application note on oscillators here:
http://www.fairchildsemi.com/an/AN/AN-118.pdf
Lots of info and the formula is also there. Hope it is helpful.
MP

 

[Ted1]

Thanks MP.
It was very helpful.
I can now move a step forward with my analysis.
Do you happen to have a good source of info on D flip flops . I want to use one as a start and stop gate.

 

[MP1]

Actually, I do. I have attached it in PDF format. Good luck with the project! Let us know how you did on it.

MP

flip_flops_and_momentaries.pdf

 

[ahmedlac]

Thanks for your input, do you know of the formula to calculate the frequency , when using two not gates.

 

[audioguru2]

Here's the other one:
View attachment 38210

 

[hazanohazizul]

hai.... can someone help me, i was during the digital radar speedometer project but i don't know what kind of Laser Diode and Laser LED that been used, can someone give me a part number PLEASE.....

 

[hazanohazizul]

Hi....
Do you know what kind of Laser Diode and Laser LED that been used in this project....
Can you give me the part number please.....

 

[audioguru2]

The laser receiving diode is wired so that it is forward biased and is conducting all the time.
I don't see how it can give an output.

 

[hazanohazizul]

laser diode it is not for transmitted but it for receiving a spot of light or a FC frequency

 

[audioguru2]

laser diode it is not for transmitted but it for receiving a spot of light or a FC frequency

There is no such thing as "a laser receiving diode". It is just an ordinary photodiode that is sensitive to visible light.

 

[MNA]

Then Audioguru, how can the crkt work..... Is there any way to make it work?

 

[audioguru2]

I don't think that the circuit works with its photodiode backwards and without an amplifier.

 

[MNA]

So, can't it be corrected easily.....
can 74LS be used instead of 74AS ?