help on DIY radar project???

**DAmp** · 04-16-2011, 08:33 PM

Ok i need some help i think this is my first post. I've lurked around for a while before but now i just need some help on doing a brute radar detector.

I already own a whistler pro 78 for ~3yrs and a passport 9500IX (if thats right) for about 6months.... but i need to make a project on a radar detector.

Basically i am using multisim 10 and have only found one schematic that looks like it might work. here's the link: http://www.high-voltage-lab.com/105/...radar-detector

The problem here is in multisim i can't find an antenna simulation so i would have to use a) a ferrite bar component, b) an inductor coil or c) make my own.

I am barely learning this so the radio thing is still not completely there. The schematic assumes that a regular antenna is used inside the radar, but i do not know specifically how the radar detectors antenna works.

My second problem is arranging the circuit so that it works with a 12V i.e car battery since its set up to a 9v which would not work.

I need to set my circuit so that it can detect atleast one band but i was shooting for x, k, ka. I think by swithching the potentiometer one can change the frequency it picks up.

Problem is im not completely sure how to simulate a radar gun wave going to a radar detector?

i was hooking up an oscillator to the would be antenna and going from there but i realize that i was getting to high a voltage. The ocillator is set at 100Vpeak (amplitude) and the freq. to say 34ghz(ka) but the last amplifier produces an output of KILOvolts which im guessing would fry my speaker which alarms of a band.

here's what i have right now. attached any help would be much appreciated. I am trying to look at all the math that goes into each op amp setting and try to solve these problems.

A very important question i had is: when the wave of the gun is in the air say Ka at what amplitude would that reach the antenna? the amplitude would be vpeak and im guessing it has to be something very small perhaps around 50mV ?

i am still doing research but i just want some input on this thanks for the help.

projectcapture.jpg

**North Alabama** · 04-17-2011, 04:21 AM

A 1458 is just 2 -741 op amps that are usually seen around +/- 2-18 vdc (depending on what it is used for). A 12 vdc will not hurt, may decrease/increase the Av slightly so R5 maybe have to be adjusted slighty different for the back ground. Use your basic electronics, Vcc/R5//R3+R4= Ima for a general ideal. This circuit is so crude and 25 years ago, I do not think it will work with modern low power pluse radar unless saturated. I would look else where for a more modern drawing. Maybe a fellow member has a better one....

**Swamp** · 04-17-2011, 10:50 AM

Here are several links that other forum members have posted here over the years that may or may not give you some useful information. The first one is the website for a very respected forum member, Jimbonzz.

http://www.kc8unj.com/radar/
http://www.antennadesignassociates.com/

http://home.comcast.net/~ronk7rj/gunplexer/Document.pdf
http://www.edparadis.com/radar/
http://servv89pn0aj.sn.sourcedns.com...mil/index.html
http://www.engr.sjsu.edu/rkwok/projects/horn_B.PDF
http://servv89pn0aj.sn.sourcedns.com...eed/index.html
http://www.powerpulse.net/
http://www.ladyada.net/make/wavebubble/index.html

**DAmp** · 04-18-2011, 09:43 PM

Thanks guys this is MUCH appreciated i will review all the info you guys suggest. I'll post back and report just not able to all the time because i'm getting everything done for finals.

M

**DAmp** · 04-19-2011, 02:57 AM

got a brute jammer going for now just need to get the right frequency for the pulses of the leds.

Do you guys know how i could use a comparator so that it could compare frequencies such as if input = 33.4ghz to 36.0ghz then use a differnt buzzer for the radar circuit?

and also how what could i the laser jammer one to pick up laser pulses coming in so it doesn't have to be constantly on? I think its a IR-diode? but not sure how the circuit would look any help is appreciated.

wont let me upload the schematic capture for some reason but its using the LM555.

**DAmp** · 04-19-2011, 11:58 AM

brute laser jammer schematic.jpg RD&LJ_test1.jpg

I'm having trouble seeing were the Laser part would be grounded once attached to the radar circuit. Also the 500K of R5 is just a test value, i still need to work out the correct value. I changed the op-amps to LM741 but now the circuit blows C1 within milliseconds of the simulation running and makes everything go haywire. I think the voltage amplification of the 741 might be too high.

I also used the suggested value for the antenna in the original schematic on the site, and i think the ground to the RD circuit should be at the antenna.

**DAmp** · 04-19-2011, 12:03 PM

do you know how i would be able to saturate it??? i did look for more shcematics but its hard to find. I found some on freepatentsonline.com but they are very complex and would take a lot of time for me to completely analyze them which i don't have. I was just hoping on using a logic gate to filter out signals if that is possible. Its an end of the semester project, i don't think i have to show a modern RD. Just use basic circuits and electronics to show what they are capable of doing. Thanks.

**North Alabama** · 04-21-2011, 01:15 AM

I was looking for the schematics for a old fuzz buster or maybe a simple fox but did find what you found, a sentry drawing. If you had a old simple cheap RD to draw and steal parts from would be nice (antenna, crystal, tuned oscillator, etc). Not knowing your resources and what you can use, it is hard to help one over the internet, your instructor should be of great value. The simple RD detector drawing above is using 1.5vdc batteries to get Vcc the way it is drawn. When altering or testing circuits, figure values and use a variable PX (variac in AC) to slowly increase the V in small amounts watching V (across caps not to blow them), I meter on the px, V points of interest and anything that has resistance will cause heat if to much I is running through it, something is wrong then stop and refigure and sub another value, use the tech spec sheets on trans or ops to note the min and max values, great building and troubleshooting tools way not to burn up things for heat and the smell will give away trouble that is fixing or has happened to repair something, just don't burn the tip of the finger (or an AC shock). You maybe doing something that is unsafe trying to sub a input source by exceeding limits, if something gets hot, stop. Does your school have a base ball team with a radar gun? I thought that you were going to use this home made RD in your auto because you wanted it to be 12v. There are many circuits on the net and in your electonic class books to draw from, it just takes time to figure values and resources to stick in the circuit to design and build something, esp a working RD which will be costly getting the parts. I am still looking...

**DAmp** · 04-21-2011, 03:36 AM

hi thanks i did not know that it was meant to run on 1.5v batterries. Was it supposed to be a total of 9v ? i was just thinking of leaving it as 5 or 9vdc and using a voltage divider to show the 12v of the car. Its just a simulation nothing being put together just a report i need to turn in for the semester.

The 741's seemed to give to much gain but its difficult to know what gain is the necessary since the antenna is not really being simulated with a signal.

I was able to come up with this after 2 days of some hard work and also had a computer crash in the middle stayed up all night.

This is a rough laser jammer if this is possible. Would go at 200hz for the 200pps and also has photosensitive transistors to trigger it.

made the pulse generator, converted 2 dual amps in another schematic and put together a 5vdc to 12vdc to drive the leds again. Of course this is all theoretical because i'm not sure there would be enough current to run the leds at the necessary power.

Could also throw some type of logic chip there to have brute force jamming just nanoseconds before the laser does full blast and then a pulsing shceme and also a timer to shut off after say 5 secs to slow down...

But i'm too tired for now ill leave this for another time. Still need to work on trying to get the LED's to actually trigger on a pulse signal.

**North Alabama** · 04-23-2011, 12:45 AM

The drawing shows a battery with a dash line and another battery symbol. That is saying that more than 2 batteries are used in series to get 9v. If it was a solid line between the 2 battery symbols, then it would be 2- 4.5v batteries in series. Keep up the good work.... PS- the drawing is very crude and can be misleading..