gbell@pnet12.cts.com (Greg Bell) (01/17/89)
Has anyone ever heard of building a simple radar detector using just one
op-amp? Radio Electronics had an interesting circuit a while ago that was
basically an op-amp with a capacitor connected across the inverting and
non-inverting inputs of the amp. Aparently, this arrangement allows
detection of various RF energies...
Greg Bell_________________________________________________________
Hardware hacker |
Electronics hobbyist | UUCP: uunet!serene!pnet12!gbell
EE major at UC San Diego |brian@ucsd.EDU (Brian Kantor) (01/18/89)
A while ago it was popular to make a radar detector out of a simple high-pass/antenna (horn/waveguide or small dipole array), a detector diode, and some DC amplification. The idea was that there wasn't much else on the road that would provide RF energy at those microwave frequencies, so it had to be radar. It worked, sort of. The problem was that these were so numb that Le Flic would be writing you the ticket before the detector triggered. Nice toy, but not very useful. Buy an Escort. - Brian
dleigh@hplabsz.HPL.HP.COM (Darren Leigh) (01/19/89)
In article <311@serene.UUCP> gbell@pnet12.cts.com (Greg Bell) writes: > Has anyone ever heard of building a simple radar detector using just one >op-amp? Radio Electronics had an interesting circuit a while ago that was >basically an op-amp with a capacitor connected across the inverting and >non-inverting inputs of the amp. Aparently, this arrangement allows >detection of various RF energies... Wasn't that for detecting "scalar gravity waves"? They used that to detect black holes and supernovae, etc. I don't even think it was in an April issue. ======== Darren Leigh Internet: dleigh@hplabs.hp.com UUCP: hplabs!dleigh
gbell@pnet12.cts.com (Greg Bell) (01/19/89)
Right... they talked about being able to detect all sorts of space
generated energy. As a side note, they claimed the circuit could be used as a
radar detector.
Greg Bell_________________________________________________________
Hardware hacker |
Electronics hobbyist | UUCP: uunet!serene!pnet12!gbell
EE major at UC San Diego |wwg@brambo.UUCP (Warren W. Gay) (01/24/89)
>In article <311@serene.UUCP> gbell@pnet12.cts.com (Greg Bell) writes: >> Has anyone ever heard of building a simple radar detector using just one >>op-amp? Radio Electronics had an interesting circuit a while ago that was >>basically an op-amp with a capacitor connected across the inverting and >>non-inverting inputs of the amp. Aparently, this arrangement allows >>detection of various RF energies... > >Wasn't that for detecting "scalar gravity waves"? They used that to >detect black holes and supernovae, etc.... >Darren Leigh >Internet: dleigh@hplabs.hp.com >UUCP: hplabs!dleigh The gravity wave detector was a more recent (I think). I recall the radar detector worked simply because the capacitor was required for coupling or DC blocking or something, but the leads were carefully cut to a particular length to match the frequence of the radar involved. The capacitor leads was thus the "antenna" for the microwaves. The gravity detector I built on a bench one night. Its rather interesting to watch, but I had no chart recorder and didn't feel like spending time on a data capture interface & software for the VIC 20. I used LM3900 op amps, of which I have a whole box of, instead of the suggested circuits. 73s de VE3WWG (Warren)..............LSI represents Large Scale Investment, .................transistors are "discrete", but tubes are just plain fun. ................Bramalea Software Systems Inc...!utgpu!telly \ !brambo!wwg ...................!{uunet!mnetor, watmath!utai}!lsuc!ncrcan /
strong@tc.fluke.COM (Norm Strong) (01/27/89)
In article <1400@ucsd.EDU> brian@ucsd.edu (Brian Kantor) writes: }A while ago it was popular to make a radar detector out of a simple }high-pass/antenna (horn/waveguide or small dipole array), a detector }diode, and some DC amplification. The idea was that there wasn't much }else on the road that would provide RF energy at those microwave }frequencies, so it had to be radar. It worked, sort of. } }The problem was that these were so numb that Le Flic would be writing }you the ticket before the detector triggered. Nice toy, but not very }useful. Another solution, which I have used with great success for about 10 years, is to drive no more than 9 mph over the speed limit. The beauty of it is that it's absolutely free, and it works everywhere but Illinois. Commence firing! -- Norm (strong@tc.fluke.com)
myers@hpfcdj.HP.COM (Bob Myers) (01/28/89)
>The gravity wave detector was a more recent (I think). I recall the
Gee, I've got a *great* gravity detector here. See, I hold it in the region
to be tested, and let go - if it falls, I assume that gravity is still
functional in that region.
Plans available for a "nominal" fee.
;-)
Bob Myers | "Man will occasionally stumble over the truth, but
{the known universe} | most of the time he will pick himself up and continue."
!hplabs!hpfcla!myers | - Winston Churchill A-N-Onymouse@cup.portal.com (John - DeBert) (01/28/89)
> >Another solution, which I have used with great success for about 10 years, is >to drive no more than 9 mph over the speed limit. The beauty of it is that >it's absolutely free, and it works everywhere but Illinois. > >Commence firing! >-- > >Norm (strong@tc.fluke.com) Not in California. Mostly. Generally speaking, on the freeways and unincorporated highways, where the Calif. Highway Patrol has jursidiction, you are likely to get stopped if you exceed the speed limit by five mph or if you are going faster than the flow of traffic by five mph. Sometimes, they'll let you slide at up to ten mph faster, but don't count on it! There was a general rule followed by the CHP at one time - recently. I don't know ifthey still do this: "up to five over (speed limit), may stop, may cite; five to ten over, may stop, must cite; ten over and up, must stop, must cite." In the big cities, it's easier to get away with speeding, especially when everyone else is too. They are more interested in keeping traffic going than catching anyone doing more than 55. In city jurisdictions, though, that's completely different. It depends on the city policy and the idividual cop. You can get a ticket for going only two mph over the limit. In Pacific Grove, CA, you can be stopped for doing the limit! A-N-Onymouse@cup.portal.com (and a few other places.)
leres@ace.ee.lbl.gov (Craig Leres) (01/30/89)
A-N-Onymouse at cup.portal.com writes: > "up to five over > (speed limit), may stop, may cite; five to ten over, may stop, must cite; > ten over and up, must stop, must cite." I think you meant, "five to ten over, must stop, may cite." With that correction, your observations match mine. Craig
A-N-Onymouse@cup.portal.com (John - DeBert) (01/31/89)
Just heard a news story on KUSW that said that some police departments were testing laser speedd "radars." No details were provided about how they work but it did say that the laser had to be aimed very carefully to work correctly. Also mentioned, laser detectors for cars to detect the speed traps. A-N-Onymouse@cup.portal.com
A-N-Onymouse@cup.portal.com (John - DeBert) (02/01/89)
>A-N-Onymouse at cup.portal.com writes: >> "up to five over >> (speed limit), may stop, may cite; five to ten over, may stop, must cite; >> ten over and up, must stop, must cite." > >I think you meant, "five to ten over, must stop, may cite." With that >correction, your observations match mine. > > Craig I heard it from a CHP officer and I am sure that is what he said. I have noted some inconsistency in practice also. During aircraft patrols, they tend to let people go at up to fifteen over, except multiple vehicles, coaches and big rigs. At least they do between Salinas and San Jose. JJD A-N-Onymouse@cup.portal.com
depolo@eniac.seas.upenn.edu (Jeff DePolo) (02/01/89)
In article <14101@cup.portal.com> A-N-Onymouse@cup.portal.com (John - DeBert) writes: >Just heard a news story on KUSW that said that some police departments were >testing laser speedd "radars." No details were provided about how they work >but it did say that the laser had to be aimed very carefully to work >correctly. > >Also mentioned, laser detectors for cars to detect the speed traps. > >A-N-Onymouse@cup.portal.com There is a laser speed measuring device currently being tested. It's made by a company in Littleton, Colorado (don't remember the name). According to the specifications, the beam width is only 6' at 250 feet, making it VERY hard to detect. Since it will be switched on only when a car is within range, detection is almost impossible. Add to that the coherent effects of a laser beam and you're chance of picking up even some of the reflected signal are next to nil. The unit is supposed to seel for about $3,500. This is more than twice as much as the best radar unit on the market today which is only $1,500. One of the most popular radar units these days (a favorite of my home state, Colorado, and of many others) sells for UNDER $400. I don't see much of a market for the laser-radar units. However, with such a narrow beam width, they would be very effective in high-volume situations where normal radar is useless because of is wide beam width. Most normal radar units range anywhere from a beam width of 12 degrees to 25 degrees. By the way, the beam width is measured from the half-power points off the center of the axis of the beam. So the beam is actually wider than 15 degrees (or whatever the horn on the antenna is rated at). This makes radar useless when there is more than 1 car in or near the beam. I guess the laser radar would be nice in that respect, but it probably won't make the state any richer since any officer can fill his ticketbook given just a normal radar unit and any decent stretch of highway. $3,500 dollars of your tax dollars may go toward buying a laser radar unit, just for the purpose of taking even more money from you in the form of speeding tickets. Ain't America great? --- Jeff +----------------------------------------------+------------------------------+ | Jeff DePolo [depolo@eniac.seas.upenn.edu] | o The best things in life | | => The University of Pennsylvania <= | come in six-packs. | | Class of 1991 - Computer Science Engineering | o Life begins at 85 MPH. | +----------------------------------------------+ o It's not illegal if they | | DISCLAIMER: Someone else used my account. | don't catch you. | +----------------------------------------------+------------------------------+
leres@ace.ee.lbl.gov (Craig Leres) (02/02/89)
A-N-Onymouse at cup.portal.com wrote: > "up to five over > (speed limit), may stop, may cite; five to ten over, may stop, must cite; ^^^ ^^^^ > ten over and up, must stop, must cite." I hate to nitpick or be overly dense, but I have difficultly seeing how the Chippie expects to cite you if stopping you is optional. Craig