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Unanswered Questions





Arduino Remote March 2015

My Sony BluRay/DVD player came with a very complicated remote control. I don't need half the buttons! Is it possible to make a simplified replacement remote using an Arduino and simple buttons with an IR-LED?

#3151
Terence Rodriquez
Raleigh, NC


Obsolete IC Hunt February 2015

I ran across an old issue of a hobby magazine which had an article “Time On Your Hands” November-December issue circa 1973. I am trying to find a source for the Mostek MK5017A BB which is used in this article. Does anyone know where I might purchase a couple of these chips at a reasonable price?

I have spent several hours on the Internet and have not been able to locate a supply from any other place. Maybe one of your readers would have some of these they might be willing to part with for such a good cause.

#2151
Ed Edmondson, PhD
via email


HD44780-based LED Display: Scrolling Text False Start January 2015

I have been experimenting with scrolling text on some HD44780-based LED displays of various sizes. The commands I talk about below are those for that device, not any particular PIC code.

I first clear the display and home the cursor sending a 01 command to the display. Then, I change to One Line mode with a 48 command. A long text message is then sent to the display using the data mode in a loop to send all the characters. This message is 72 bytes long and should be going into LCD RAM locations 128 through 199.

At this point, I have tried a number of commands to reliably reset the active window to the start of my message, but none of them seem to work for all the different displays I have tried this on.

On some of the displays, nothing works. Then, the text is scrolled using the Pan Right command: 24 in a loop that repeats it 136 times to display the complete message two times. The scrolling does work, but sometimes it starts at the beginning of the message and other times it starts at the 41st character. This action seems to be random.

As I stated, I have tried inserting several different commands just before the scrolling routine but none of them have worked. These commands include repositioning the cursor to position 128, the start of the first line, homing the cursor (2), and adding a cursor right and a cursor left command after that. None of these measures seems to have any effect.

Does anybody know of a reliable way to have this scrolling message always start at its beginning? If possible, I need a solution that works on all HD44780-based displays. I know this is a tall task and may need to use different approaches for different displays.

#1153
Paul Alciatore
Beaumont, TX


PointSource/Qioptiq Pin-Out January 2015

I purchased a model P1600- Gemini PC-4 mfg. by PointSource which is now called Qioptiq. It is a three laser diode device, 660-680 nm. It has three fiber steel shielded optic cables. It has two input ports, 26-pin and nine-pin. I think the 26-pin port is for control and monitoring. The nine-pin I think is for power in. I cannot find the pin-out specifications to be able to power up. Emailed Qioptiq ... no reply.

This device will be used in a quantum entanglement project if I can get the pin-outs. Any information would be extremely helpful.

#1152
Michael Duc
Vancouver, WA


What’s Up With 3V Sensors? December 2014

I'm working with MEMS devices — especially the new 3V sensors.  Compared with older 5V sensors, they seem more susceptible to noise. It seems as though dynamic range would naturally be lower, given the lower operating voltage. Are 3V sensors really a compromise?

#12144
Seymour Holland
Peoria, IL


Commodore Troubleshooting October 2014

I recently inherited a 1980's era Commodore SX-64 computer. Though it looks cosmetically perfect, it doesn't power up (i.e., the little monitor lights up with a plain gray color, but there is no sound or picture). Anyone have any pointers on where to begin troubleshooting this unit?

#10142
Dani Sanders
Salt Lake City, UT


Antenna Preamp September 2014

Is there a CMOS op-amp with low noise, good common-mode isolation, and unbalanced output available? I would like to use it in a loop antenna preamp in a location that has an extremely high power-line noise level. 

E-mode whips with a preamp are definitely unusable. This antenna would be untuned and intended for use below 30 MHz.

#9141
John R. Seeley KI4LTB
Palm Bay, FL


Renewing Permanent Magnets June 2014

I have an old style hand crank telephone generator. It works, but output voltage is low due to the four horseshoe magnets it uses being weak. What is the best way to revitalize these magnets to bring the generator back to like-new operating condition?

Also, how can I tell when — as a result of the revitalization process — the magnets have achieved maximum strength and won't get any stronger?

#6145
David LeFevre
Ontario, NY


FM Instead of Wi-Fi June 2014

I would like to use a device such as a Pi or Arduino to connect to an Ethernet. I want to send/receive data wirelessly via digital FM instead of Wi-Fi to communicate with devices where the Wi-Fi/internet connection is unavailable, but still relatively close (suitable for low power FM where FCC regulations would not be an issue).

High speed data transfer such as for streaming video is not a must, but 100-200 kps would be ideal. This would, of course, vary depending on the strength of my signal.

Can I buy a board with Ethernet and simply I/O data to an FM transceiver? Any suggestions to help me get started would be great.

#6141
Gary McPherson
Wyoming, MI


3D Printer Materials Reference May 2014

I’m designing an RC dune buggy using a 3D printer, but I can't decide which material to use. I want it to be as light and strong as possible, but I need a reference that shows (for example) the strength of an I-beam made of ABS vs PLA. Does anyone know of such an engineering reference?

#5141
Peter Murphy
Pensacola, FL

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