I’m looking for some pointers on winding coils. On a second layer of winding, should the direction reverse when reaching the end of the core, or return to the starting side and wind in the same direction? It seems like winding in the reverse direction would cancel out the field. Does it matter which direction?
#1194
Jordan Bracegirdle
Toronto, CN
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Is it possible to replicate tubular bell tones with a microcontroller? I’m needing realistic, deep, resonating tones. If so, are there any micro requirements that would make one device more suited over others and how do I create the tones? I want to program short 10-15 sec jingles of my own composition.
#1193
Sara Hanchett
Forest Grove, OR
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I have a bunch of old optical disks that have data archived from about 20 years ago that I would like to access. I found the stand-alone drive in a box of old computer junk, complete with the big SCSI cable. Problem is that I don’t have the computer anymore that has the SCSI card to plug it into, and don’t even know where to begin to look for one.
Is there something comparable that will work with a modern computer? An SCSI to USB adapter maybe? What about drivers? The old machine was probably Windows 98.
#1192
Mark Cisneros
Columbia, TN
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I have a 100 amp 110 volt DC generator. I want to convert the output to 60-cycle AC. Does anyone have a schematic or info to build a converter? How much power loss can I expect in the final converted output? Thanks for any info.
#1191
Lucio Saunders
Indianapolis, IN
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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
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Answers
CD players for professional/DJ market have variable pitch built in.
Erik von Seggern
Escondido, CA
I would be surprised. CD players are designed to KEEP their speed. I would convert the song to one of the usual audio file formats (mp3, wav) and run it on a computer with the free audacity tool. That lets you change the speed and even allows you keep the pitch! (Effect -> Change Tempo; Effect -> Change Speed). I use audacity constantly.
Werner G
via email
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
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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
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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
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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
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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
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