I want to build a backup proximity detector like many newer cars have, as a fun, useful project. The type that beeps in reverse when something is behind my car; faster beeping means the object is closer. I'm new to electronics, and I need help designing the circuit. I thought of using the PING))) sensors available from Parallax to sense the distance to objects. Any help with the circuit is welcome. It would be preferred to have it auto-activate when in reverse, but I could just as easily flip a switch mounted next to the shifter to activate if it becomes too complex.
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We have a Smart Meter installed for our home electric utility billing. Is there a way to read data from it to log usage data to a computer? I want to analyze my power usage by day of the week, time of day, devices and appliances in use, etc. Does the meter itself keep a log of this info that can be read or would I have to have a spreadsheet or other program to track it?
I'm not looking to interface any hardware to it. It would appear to have an RF link with the power company that might allow access. Any information about these meters would be helpful.
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I have in my junkbox what I believe to be ceramic resonators. What is the best way to test them to determine their frequency?
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Certain techs and engineers still have a need to sample and view composite/NTSC video in its three axes form, that is: X axis (horizontal), Y axis (vertical), and Z axis (intensity).
In the past, this was accomplished using a CRT o’scope: horiz sweep to H input; vert sweep to V input; and video to Z, or intensity modulation input. Since CRT scopes are bulky, heavy, and, in most cases, not battery powered, a PC/digital scope with capture capability would be very handy for field use.
None of the scope ads I’ve seen list these features. Can anyone make some recommendations?
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I'm looking for a circuit to homebrew an AVR for a 25 KVA (20 KW), 60 Hz, 1,800 RPM, three-phase, 240/480 volts Star with a neutral synchronous generator that is wired up as a single phase zig-zag 240/120V output.
I'm trying to help out a brother Vet who uses this generator to supply power to his off-grid site. I'm a Seabee Vet that was a CE in the Navy. I used to work on this type of generator when they used relays to control the voltage output.
I have some experience in using the PIC and the Arduino Uno/AVR microcontroller. I would appreciate any help and offer my thank you in advance. The cost of a replacement of this hybrid analog-digital voltage regulator is way beyond his means at this time.
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This is my first project using all digital Hitec servos. My question is: Are these new digital servos stable if I switch the input signal into the servo — between sources — while keeping power connected? I know old analog servos would have a nervous breakdown if I switched sources while the servo was under power. I know the new digital ones have a safe position. Should I program this, cut the signal from the primary source, wait for the servo to go to a safe position, then switch on source B?
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I’m trying to emulate the chasing lights that used to be popular under the awnings at the cinema. I have a chasing LED circuit that works well, but I want to turn the LEDs off slowly to leave the comet trail effect. I’ve tried putting a 2,200µF cap in parallel with each LED with limited success.
There must be a simple way to have the LEDs turn on quickly and then fade out.
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To provide a good answer your question, more information is needed. With the configuration of a LED and limiting resistor in series, with a capacitor in parallel, a time constant can be calculated. with a 2200μF capacitor and a 100Ω resistor, the time constant would be 0.22 sec. This would light the LED for about 1 second. I don’t know what your problem could be.
LEDs are pretty much digital (binary) devices, meaning they turn on and they turn off. They do not fade out when the voltage gets too low - they turn off.
The only way to make them fade out is to use an oscillating circuit to change/increase the time the LED is off vs the time it is on.
A joule thief voltage increasing circuit can be used to do this but so can a digital circuit.
The joule thief circuit could be made to do this if you use another circuit to control the voltage going to the joule thief circuit. Start with 1.0V for full brightness then decrease the voltage down slowly to ~ 0.20 V to dim & then turn it off.
The turn-off voltage will be higher (than 0.20V) if you use a simple joule thief where the number of windings/loops is the same for both sections. The efficient joule thief where the # of windings/loops is on a ratio of 2:5 and the 2-loop section goes to the base of the NPN transistor should have a lower shut-off voltage. I’ve had this circuit, with loops of 8:20 (8 to 20, 8 going to the base of the NPN transistor) still giving light down to 0.25 volts, so I don’t really know when it will turn off but you can simply turn off the voltage to the circuit when it gets to ~ 0.2V and that should look pretty good.
See my web site article on the Joule Thief Information Page at: http://cs.yrex.com/ke3fl/htm/JouleThief/JouleThief.htm - for all the experiments I did to find the best (efficient) joule thief circuit.
I have an old guitar “echo” pedal that is dead. After some troubleshooting, it appears the SAD1024 chip in the unit has given up the ghost and I have been unable to find a replacement chip.
Is there a substitute for it or a source for replacing it?
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I have a generator and some old but useable communications gear that I’d like to donate to the hurricane victims in Puerto Rico. Since it's somewaht specialized gear, how does one go about getting it into the right hands so it will do some good? Is there some sort of national clearing house or maybe ham volunteer groups?
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With high powered laser prices dropping like crazy, I decided to pick up a 3W blue laser from eBay for $50 to experiment with.
I’m concerned about eye damage and would like some advice on eye protection. What makes a pair of laser goggles good and what should I stay away from?
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