Search found 82 matches

by jimmy101
Tue Dec 25, 2012 9:57 am
Forum: General Discussion
Topic: Would the US electrical code allow this ?
Replies: 9
Views: 2652

Re: Would the US electrical code allow this ?

If you want more light than what a typical lighted switch provides you can just use a standard wall mounted "three-way" (Single-Pole, Double-Throw SPDT) switch. Three-way switches are typically used to control a circuit (like lights) from more than one location. Here though you are controlling two l...
by jimmy101
Mon Dec 03, 2012 3:03 pm
Forum: General Discussion
Topic: Light dependent resistors...
Replies: 7
Views: 1624

Re: Light dependent resistors...

never mind
by jimmy101
Sat Jun 23, 2012 12:04 pm
Forum: Projects & Kits
Topic: Bat Detector
Replies: 2
Views: 3076

Re: Bat Detector

A few more comments on the circuit. 1. The quoted opamp gains are way off. At say 50KHz the maximium gain for the particular opamp is only 20x since the Gain Bandwidth product for that opamp is 1MHz. For the pair of opamps the maximum gain is therefore ~400. At DC the gain is unity. 2. The feedback ...
by jimmy101
Sat Jun 23, 2012 11:46 am
Forum: General Discussion
Topic: Bat Detector
Replies: 6
Views: 2207

Re: Bat Detector

It should be pretty easy to make a detector that is both heterodyne and digital. For the heterodyne circuit in the 2011 N&V you would just need to add a digital divide chip (e.g., CD4024B) and perhaps a single resistor to limit the output to the ear piece. Put a DPST switch in that shunts the amplif...
by jimmy101
Sun Sep 18, 2011 8:56 am
Forum: General Discussion
Topic: Generator Question
Replies: 20
Views: 3077

Re: Generator Question

For any small engine I would assume that the general replaceables need to be replaced. (Always go with the simplest and cheapest fixes first.) New plug(s), new air filter, and in particular, a new fuel filter. If the fuel filter is starting to plug up the engine will run lean but may still seem to o...
by jimmy101
Thu Sep 15, 2011 12:49 pm
Forum: General Discussion
Topic: Color scanners and copiers...
Replies: 4
Views: 1070

Re: Color scanners and copiers...

Illuminate with white and detect with three sensors, ones for red, blue and green. Not that hard (and the detectors don't have to be looking at the same spot at the same time). Or, if the detector responds well to all colors, just use three sensors with different color filters. Black and white scann...
by jimmy101
Mon Jul 25, 2011 3:23 pm
Forum: General Discussion
Topic: Carbon Monoxide?
Replies: 9
Views: 1516

Re: Carbon Monoxide?

1. I would think that air supply is one big difference. A gas range has an exposed flame with lots of access to air (adequate air is needed to reduce CO2 production). A hot water heater places the flame inside an enclosure which increases the chances of an inadequate air supply. 2. Visibility probab...
by jimmy101
Mon May 30, 2011 8:04 am
Forum: Projects & Kits
Topic: Bat Detector
Replies: 2
Views: 3076

Bat Detector

Very interesting article, one that I might give a try. Two points / questions though. In Figure 5 (Board Layout) it looks like there should be a cut in the Vero board trace underneath capacitor C4. Also, there is no connection to the battery negative. There should be a connection between the trace i...
by jimmy101
Sun May 29, 2011 2:02 pm
Forum: General Discussion
Topic: Commenting on article in Nuts & Volts
Replies: 6
Views: 1353

Commenting on article in Nuts & Volts

Does Nut & Volts have a place where you can comment on articles? Some years back there was an article on measuring the speed of light that I always wanted to comment on. There were typos in the data table and the technique spent a lot of time dealing with gate delays when it wasn't necessary. In the...
by jimmy101
Sun May 29, 2011 1:57 pm
Forum: General Discussion
Topic: FREE Phone number lookup,.... PHONY
Replies: 2
Views: 953

Re: FREE Phone number lookup,.... PHONY

Basically there is nothing illegal about lying. "Truth in advertising" laws often don't apply to online content, and even for traditional advertising venues, lying is common.
by jimmy101
Fri May 27, 2011 1:25 pm
Forum: General Discussion
Topic: The "Great' lawnmower legal settlement
Replies: 15
Views: 3199

Re: The "Great' lawnmower legal settlement

It is not like the tech writers from the 60's, 70's etc weren't above wildly exaggerating claims either. Over claiming car engine horsepower is a decades old 'trick" of car makers. Extravagant claims of audio power ratings have been around since the 50's. Is that watt rating "peak" or "RMS" or ...? ...
by jimmy101
Wed May 04, 2011 3:17 pm
Forum: General Discussion
Topic: Flipping video
Replies: 12
Views: 2421

Re: Flipping video

jimmy- The cameras are actually looking through portholes, and lighting becomes a problem with using a mirror. Why? A mirror reflects better than 95% of the light that hits it so there isn't enough attenuation to be a problem. The mirror can be within an inch or two of the camera's lens, and the mi...
by jimmy101
Tue May 03, 2011 5:15 pm
Forum: General Discussion
Topic: Flipping video
Replies: 12
Views: 2421

Re: Flipping video

You said a mirror won't work. Why not? Just point the camera at a small mirror and point the mirror at the line.

Usually the obvious solution is the best solution.
by jimmy101
Sun May 01, 2011 9:47 am
Forum: General Discussion
Topic: Moisture vs Resistance
Replies: 11
Views: 2696

Re: Moisture vs Resistance

I would suspect that the meter they are using is similar, if not identical, to a wood moisture meter like http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&productId=100651808&langId=-1&catalogId=10053&ci_src=14110944&ci_sku=100651808&cm_mmc=shopping-_-googlebase-_-D25X...
by jimmy101
Sun Apr 24, 2011 9:22 am
Forum: General Discussion
Topic: low fuel alert
Replies: 26
Views: 3482

Re: low fuel alert

Perhaps just a low pass filter? Resistor in series followed by a cap to ground. Pick the values so that RC is say 10 seconds. 10Meg resistor and a 1uF cap seems about right. Take the input to the alarm's comparator from between the resistor to cap connection. This won't give any hysteresis but it wi...