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Unanswered Questions





Tuning The Music November/December 2018

Is there a way to vary the speed of a music CD player? I play my instruments along with the recordings and need to vary the pitch slightly to match the tuning of my instrument. We used to do this easily with vinyl by varying the speed of the turntable.

#11188
Klaus Herman
Raleigh, NC


About Resistors November/December 2018

Could someone explain what pull-up and pull-down resistors are, when and how they’re used, and how to calculate their values?

#11187
Andy Dietrich
Dallas, TX


Good Timing November/December 2018

I have an old model automotive timing light that attaches between the #1 spark plug and wire. How can I make an inductive pickup to sense the signal so I don't have to detatch the wire? Is it even worth trying to

#11186
Ricardo Stewart
Hanover, MD


Proximity Detector November/December 2018

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.

#11185
Gregory O'Rourke
Newark, NJ


Audio Replay Device November/December 2018

Is there a device that will continuously "listen" to audio (via a mic or an earphone jack) and allow the user to push a button so that the device will repeat the last 20 seconds of what it just heard? I listen to scanners and ham radios, and often miss what was just said, and would like to get a repeat for clarity. I prefer a stand-alone device to an app or computer software.

#11184
John C
Montague, MI


Reflow Oven Opinions Needed November/December 2018

Anybody doing SMT reflow soldering at home? Trying to make the switch from TH to SMT. I was wondering what homebrew oven setups people are using and any tips and advice for a newbie.

#11183
Joey Dampier
Reston, VA


Logging Power Data November/December 2018

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.

#11182
Lisa Miller
Cleburne, TX


PC Joystick Interfacing November/December 2018

Is it possible to connect a joystick to a microcontroller? PIC, PICAXE, etc. I don't want to have to take apart and hack the joystick. If so, what is required?

#11181
Nick Hulst
Cedar Rapids, IA


Wireless Data To PC September/October 2018

I have a number of wireless temperature/humidity sensors made by Oregon Scientific for use as weather station sensors. I would like to use them for a data acquisition and monitoring application. Does anyone know what frequency and mode they operate on and how I might use them to send data to a PC to record seasonal trends? Would I need a microcontroller to interpret the output or could it be read directly by the PC and then logged and displayed using software such as MakerPlot?

#9184
Jai Hooley
Edmonton, AB


Something Strange With The Range September/October 2018

The effective range of the key FOB for my Ford F150 seems to have decreased over recent months. While it used to work from distances of 75-100 yards easy, now I need to be nearly right in front (10-20 yards) of my vehicle to operate the systems. I changed to a fresh battery, but no difference. Is it likely there is an antenna problem? If so, where is it located and is there a test procedure?

#9183
Les Waldroup
Charlotte, NC

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