Digital radar speedometer

[MNA]

the previous rar was page 1 ...this is page 2

about_Digitar_Radar_Speedometer.rar

[MNA]

for me all the links are working......
http://books.google.com/books?vid=ISBN0070112762&id=e_X2-LqfKaMC&pg=PA1&lpg=PA1&dq=the+encyclopedia+of+electronic+circuits,volume+6&sig=byxvoWKy4EWH_zpzUnrIxQwk4Zs

the keyworks for getting onto the right page is "2.6-GHz Oscillator for radar speed gun"

[audioguru]

Radar? Radar uses radio waves.
I thought you want to use a laser diode transmitter and a photodiode receiver.

[MNA]

Which one will be better? Were u able to open the files?
After doing a lot of searching ,I only found two speedometers one here at electronics lab(laser) and the other one in this book(radar) ....... There seems to have no other option.......
what will be the effect if 74LS is used in this crkt?.....

[audioguru]

74LS is too slow for this circuit.

[MNA]

Audioguru, what about the radar gun crkt? ..... haven't u been able to open the attached files?

About Digital Radar Speedometer:-
I want to know why a high speed ttl is required?  Why to amplify the signal?

can 74LS be used instead of 74AS?

I guess you didn't compare the datasheets: The AS is 5 times to 9 times faster than the LS.

No,I didn't get to any such datasheet ...... only found 74LS.....
I've read that 74HC series is fast but don't know the comparison b/w HC and AC....

[audioguru]

Audioguru, what about the radar gun crkt? ..... haven't u been able to open the attached files?

You attached the PDF file for the Ramsey radar display unit, but it doesn't have the receiver's schematic.
I am waiting for you to attach the schematic for the stuff you linked to. I can't open the link.

Why to amplify the signal?

The output level from a dimmly lighted photodiode is extremely low.

No,I didn't get to any such datasheet.

I get most datasheets from datasheetarchive.com . No login and no password are needed.

[MNA]

http://books.google.com/books?vid=ISBN0070112762&id=e_X2-LqfKaMC&pg=PA1&lpg=PA1&dq=the+encyclopedia+of+electronic+circuits,volume+6&sig=byxvoWKy4EWH_zpzUnrIxQwk4Zs
keyword:- radar detector

2:-
http://books.google.com/books?vid=ISBN0070112754&id=pv5F15t6B7QC&pg=PA528&lpg=PA527&printsec=8&dq=radar+gun+circuits&sig=RqFYZvotoF7AhPnG486L67pog3o

Are these links asking u a username and password ? and anything else??

[audioguru]

Why don't you attach the schematic for the laser receiver circuit?
Your 1st link has Google Book Search asking for me to login. Then it says I have the wrong password!
Your 2nd link shows a display schematic without a receiver schematic.
Attached is the display's schematic that I saved:

[MNA]

How!!!!!!!!!!!!!!
how did u save it? I can't......I checked in google about google book search and it says that the ages can't be saved nor printed.....then how did u do it.....

there r only two circuits.....One is the same as u find in the ramsey(microwave transmitter) and the other is the display crkt .........

Receiver crkt??????

[MNA]

this is the transmitter :-
http://books.google.com/books?vid=ISBN0070112754&id=pv5F15t6B7QC&pg=PA529&lpg=PA527&printsec=8&dq=radar+gun+circuits&sig=tKeGbNSf6ejD587lzpbxT3Av3ck

this crkt consists of 2.6 GHz oscillator Q2,a coupling microstripline to ant.1,a 1.1" wave probe,

[MNA]

Google says:- :o
Your books are protected

Your books are hosted on our secure servers and users can only see a limited number of pages from your books. In addition, copy, save and print functions are disabled. And you can remove any of your books from Google Book Search at any time.

:D
tell me how did u do it.....

[audioguru]

You can save anything on your monitor's screen by pressing the "Prt Scrn" button on the keyboard's upper row.
I paste it into MS Paint and crop it and save it as a PNG file. Like this one:

I didn't know that the radar receiver is just a diode and an audio transistor inside the transmitter circuit. Then the display circuit amplifies the beat note even more and counts its frequency.

[MNA]

:D great!!Thanx Audioguru.....
I read that laser speedometers are better than radar.......About that particular circuit what's your opinion.....

[audioguru]

I read that laser speedometers are better than radar.......About that particular circuit what's your opinion.....?

Our "Digital Radar Speedometer" project is titled wrong. It doesn't use radar, it uses a laser.
I don't think it works because its photodiode is backwards and doesn't have an amplifier.

The radar circuits might work. Try them.

[MNA]

Have a look on this site(about ramsey radar):-
http://www.rcgroups.com/forums/showthread.php?t=205460&page=2&pp=15

Audioguru,what is microstripline?

[oldgrandpainmi]

2 quick things-

A great source of d-Flip flops-  DigiKey.  Order their free catalog on cd or paperback (almost 2"thick).  They also have most or all of your laser diode needs.

Also, I use ScreenHunter to screen capture.  It is free, saves everything as a .bmp file (which you can save as something else) and works great!

oldgrandpainmi

[audioguru]

Audioguru,what is microstripline?

A micro-stripline is a way of wiring microwave RF parts so that the plumbing forms tuned circuits and impedance matching devices. I have never played with frequencies as high as microwaves so I don't know anything about it.
A search in Google might find a description about how it works.

[MNA]

Have a look on this site(about ramsey radar):-
http://www.rcgroups.com/forums/showthread.php?t=205460&page=2&pp=15

[audioguru]

The Ramsey radar gun kit is only good enough for a kid's science fair demo?

[MNA]

The Ramsey radar gun kit is only good enough for a kid's science fair demo?

I know that these crkts can't match with the costly made.......
But why....

2

[MNA]

7  what's the function of LM324(amplification or comparator or else) and 4093 here ?

[audioguru]

I know that these crkts can't match with the costly made.......
But why....?

They are cheap and crude. A free-running oscillator is used in the display circuit and its frequency is adjusted for calibration. A real speedometer uses a very accurate quartz cryatal oscillator.

2

[MNA]

(free running oscillator in the display circuit) Can u point me where?
the laser diode is receiving only the reflected frequency???? Doesn't it get mix with the transmitted frequency in air?
If we have two inputs with different frequncies,is there any way that we get their difference????
how can we divide by 7.76 Hz using logic ics?
Why LM324 is used?I mean what is it doing?
Thanx

[audioguru]

(free running oscillator in the display circuit) Can u point me where?

It is a Cmos Schmitt-trigger oscillator whose frequency changes with supply voltage changes and temperature changes. See my attachment.

the laser diode is receiving only the reflected frequency???? Doesn't it get mix with the transmitted frequency in air?

The laser doesn't shine on the photodiode. Maybe the laser is modulated with a tone and the doppler shift changes the tone's frequency, then the two tones are mixed in the receiver.

If we have two inputs with different frequncies,is there any way that we get their difference????

An RF mixer circuit (detector diode) gives their sum and their difference as a beat tone.

how can we divide by 7.76 Hz using logic ics?

A logic divider divides a frequency by a whole number.

Why LM324 is used?I mean what is it doing?

The beat tone is weak so is amplified. The weak beat tone has noise so is filtered. See my attachment.