Sorry...

[2FastCobalt]

I'm gonna apologize ahead of time because I'm sure that you guys have gotten this more than once and if I REALLY did some digging I could probably find a topic on it, but the looking that I have done has turned up nothing, here or on the internet, so I'm gonna cross my fingers and hope that one of you guys has some info for me...

I've got a 2006 Cobalt SS Supercharged ( non-essential information ) with some cheesy k-mart radar detector in it right now. It sucks. I figured I would have a problem with it when I paid $70 for it, but I needed something to hold me over until I could afford to do something else. The question is this: how would I go about making my own? I'd like to construct a circuit and install diodes or transistors or whatever I need to, at specific points on my car ( A Pillars, External Light Fixtures, etc ) that will communicate with the circuit ( probably located in my dash ). As I'm not INCREDIBLY well oriented in designing a circuit from scratch, I wonder if someone could let me know what all I am going to need and/or possibly how it works? It's probably more information than anyone wants to type up but I appreciate it...

Basically, I need to know what component will recieve a radar/laser signal and send power over the wire to my circuit to light up a set of LEDs, I wouldnt expect that it is too hard but I dont know where to start and I can't find a single useful schematic anywhere online ( I'm probably just stupid, but who knows ). If anyone has anywhere where I can find a schematic for just a basic radar detector I'm sure I could put it to use. If anyone has any suggestions for where I can get the essential parts? I know that radio crap offers photodiodes/phototransistors and from what I've read I think that that is probably where I need to be, but I'd appreciate a bit of guidance.

Thanks much guys, any help is appreciated.

[JDS]

Um.

I haven't seen that question before.

There is no way you can build your own radar detector and get performance even CLOSE to what you could buy commercially.

A good radar detector has extremely complex programming, a precisely calculated radar horn design, dedicated microprocessors and all of this is patented. There's really no way you'd build one one your own and get decent results.

[jimbonzzz]

Not to discourage you or anything, but what you ask is not practical. There's no way to build your own radar detector that would be cheap enough to "hold you over until you can afford something else". Modern radar detectors are complex superhetrodyne receivers.

Sure, it's possible to build some rudimentary designs at home, such as this one:
http://www.circuit-diagrams.com/dg50...r-detector.php

But in general, any simple home-built design would offer abysmal performance, and would definitely not be something to actually depend on for protection against a ticket. In order to make your own detector from scratch that would even come close to the performance of low-end commercial detectors (like your $70 K-Mart detector), it would would take a large amount of time and a significant investment, likely several thousand dollars.

[JDS]

Jim, if you built one of those with a big enough radar horn, could you theoretically get similar reception to commercial radar detectors? Obviously you would lose all false alarm filtering and POP detection, but could you just brute-force it and pick up weak signals at long range with a foot-long radar horn?

[jimbonzzz]

Jim, if you built one of those with a big enough radar horn, could you theoretically get similar reception to commercial radar detectors? Obviously you would lose all false alarm filtering and POP detection, but could you just brute-force it and pick up weak signals at long range with a foot-long radar horn?

I don't think so. You would have more gain, but I don't think you could obtain that level of performance with a high-gain horn fronting a crappy receiver that can't separate the signal from the noise well.

[MEM-TEK]

I am going to guess that this simple circuit has around 2,000 to 4,000 times less sensitivity compared to the best radar detectors. You could probably detect a microwave door opener once you got within 10 feet of it though!