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Recent Questions

2019 Issue-5


Dish Projects Wanted

I have a couple of small satellite dishes (Direct TV I think) with receivers that have been sitting in the garage for a while. I hate to throw out technology that could be repurposed. Anyone have an idea for a cool DIY project I could reuse them for?

#05191
Devin Martel
Durham, NC


Guitar Tuner

I’m trying to build an electronic guitar tuner. Is there an IC available to generate the proper tones?

#05192
Hamish Morisset
Norcross, GA


Triangle Waves

I need a circuit to generate a triangle wave from zero to five volts.

#05193
Charles A. Parham
Galveston, TX


Car Detection

I’m looking for help designing a circuit to detect cars driving up my private road. I have in mind something like the wire loop embedded in roads to sense cars at a traffic light. Can you explain the principle behind this method and how a basic DIY version might be implemented?

#05194
Ulrike Krüger
Laconia, NH


Diesel Computer Mods

There are several entities that will modify the settings on the engine control computer for a diesel Chevy pickup to increase power. I assume they are adjusting the timing curves and other parameters. Is there an adapter and software available for me to experiment with this myself?

#05195
Karel Dostál
Covina, CA


2019 Issue-4


PA system to POTS interface

I need to put the speaker-level output from a PA system on a POTS telephone line. I don’t need dialing capability, as I can connect a POTS phone to make the call, but once the call is established, I need a circuit that will:

  1. Hold the phone line open, as I’ll hang up the phone I used to make the call.
  2. Put the PA output onto the phone line, preferably with adjustable volume. I can attenuate the speaker-level PA output to line level if necessary.

If a reasonably-priced product with good sound quality (i.e., no hum, etc) is already available to do this, suggestions are welcome. I’ve found many products for recording phone conversations or putting them into a PA, but only quite expensive ones with way more features than I need that will do the simple job I want.

Thanks for any help/suggestions.

#04191
Gary Rathbun
Placerville, CA


NFL Magic Lines

Can someone explain how the first down and scrimage lines are generated on screen in televised NFL games? Obviously, it's done by computer, but I can't figure out how the angle and aspect is able to change and keep up with the constantly changing camera angles. Also, the lines are seemingly underneath the players, as if they were actually drawn on the ground.

#04192
Ryan Johnson
Jackson, MS


Solar Panels And Lightning

Are solar panels suceptable to damage by nearby lightning strikes and would they provide any margin of safety to electronic equipment in a grid-tied or off-grid system?

#04193
Alex Freeleagus
Tigard, OR


2019 Issue-3


Reset System For Cable From Both Computer And Cell Phone

My cable system needs frequent resets. That means turn the power off to the cable box (router) and to my own WiFi router, wait 30 seconds, and turn the power back on. This is really aggravating when I am in the bedroom or the garage shop trying to watch streaming video on my TVs there and the routers are at the other end of the house.

I want to build a WiFi based system so I can activate a control to cycle the AC or DC power from anywhere in the house either via one of my computers or my cell phone. Now, my phone is a smart phone, but not a name brand like Apple. It’s a Nokia and uses the Windows operating system, so the available apps are somewhat limited.

So, I’ll need an app that will work there and one that will work on my desktop computer running Windows 10. I would like some ideas on how to proceed. I would think that I could base this on an Ardunio or other single board computer which could easily handle a 30 second time-out.

I can figure out the interface to the power relay, some local PB controls, and a display. But how do I handle the controls through the WiFi? I need advise on a WiFi interface and the apps that are needed to activate it.

#03191
Edward Alciatore
Beaumont


Image Reverse

I’m building a rear facing camera system for my car that displays the image on a 7” screen mounted on the dash. However, the image appears reversed horizontally. Is there a circuit to flip the image left to right so it would be correct from the perspective of the driver? Any ideas are appreciated.

#03192
Krystian Czarnecki
Lombard, IL



Answers

Your best bet is to buy a backup camera that reverses the image for you. Many models let you select which way you want the image displayed. Depending on the resolution and night vision features you want, the backup camera can be purchased for under $20 online.

Bruce

You don't need any electronics. Instead of having the camera face backwards out your rear mirror, place it so it "looks" left or right. Then use a mirror at 45 degrees to the camera's optical axis (top view) and you'll get a left-to-right reversal of what your display shows. You could mount the camera and mirror on a plastic or plywood base and support the mirror with a small angle bracket that lets you adjust the angle so it suits your purpose. And you can move the base as necessary.

Jon Titus
Herriman, UT


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