Nuts & Volts - September 2004

Tech Forum

QUESTIONS

We have a 2001 VW Eurovan that had three keys, two of which are the remote control key fob type, and one smaller "valet" key. My wife has lost both of the remote keys, somewhere here in our house. The dealer wants over $200.00 per key to replace them. I tried to copy the remaining key at our local home center. They were able to grind a new key blank, but a tester showed that the original had an RF chip that prevents the copied key from being used.

Can a device be made or purchased that will emulate the signal the car sends to excite the RF chip and detect if a key is nearby? I could use that to search our house for the key. If it can tell me if a key is close

by, that would enable me to narrow our search and find it without tearing the whole house apart.

#9041 Jim Balderrama

San Diego, CA

from the charging of the output coupling capacitor of a bass guitar amp that uses a single 90-volt supply? Manual switching is not adequate because it does not protect against someone messing with the power cord wall plug.

#9043 Dennis Green via Internet

I am trying to find info on a kit that was offered back in Radio Electronics magazine, called the HyperClock. It was offered by an outfit named Ski Tronix, around 1991. I built one back in high school, and it has just now failed. I cannot locate the schematics or magazine issue that featured it. Searching the web has not yielded anything.

#9042

We use a Barcus Berry model Model 4000N piano mic at our church. Remembering to change batteries every couple of months before we are in the middle of a service is a pain. I want to convert our mic to be phantom powered from our audio mixer. Has anyone done this and can offer some advice?

#9044 Steven Morgan

Cumming, GA

Rich White via Internet

Does anyone have a simple circuit for taming the turn-on thump

I do quite a lot of 35mm motion picture projection work, and wonder how close to 24 frames per second the projector is actually operating. Is there a circuit for some sort of sensor that I can hold in front of the lens and measure the FPS count?

#9045 Edward Vanoverschelde

Buhl, ID

I have two questions. First, what happens when an EXE file is run on a PC? I would like to know where the contents of an EXE file will be loaded, and so on. Second, I am confused with partitions on the hard disk drive. I would like to know how the partitions (i.e., C, D, etc.) are represented on the disk.

#9046

Aditya via Internet

ANSWERS

F o r

E l e c t r o n i c s

NUTS & VOLTS E v e r y t h i n g

This is a READER-TO-READER Column. All questions AND answers will be provided by Nuts & Volts readers and are intended to promote the exchange of ideas and provide assistance for solving problems of a technical nature. All questions submitted are subject to editing and will be published on a space available basis if deemed suitable to the publisher. All answers are submitted by readers and NO GUARANTEES WHATSOEVER are made by the publisher. The implementation of any answer printed in this column may require varying degrees of technical experience and should only be attempted by qualified individuals. Always use common sense and good judgement!

Send all material to Nuts & Volts Magazine, 430 Princeland Court, Corona, CA 92879, OR fax to (951) 371-3052, OR email to forum@nutsvolts.com

ANSWER INFO

• Include the question number that appears directly below the question you are responding to.

• Payment of $25.00 will be sent if your answer is printed. Be sure to include your mailing address if responding by email or we can not send payment.

• Your name, city, and state, will be printed in the magazine, unless you notify us otherwise. If you want your email address printed also,

indicate to that effect.

• Comments regarding answers printed in this column may be printed in the Reader Feedback section if space allows.

QUESTION INFO

To be considered

All questions should relate to one or more of the following:

1) Circuit Design

2) Electronic Theory

3) Problem Solving

4) Other Similar Topics

Information/Restrictions

• No questions will be accepted that offer equipment for sale or equipment wanted to buy.

• Selected questions will be printed one time on a space available basis.

• Questions may be subject to editing.

Helpful Hints

• Be brief but include all pertinent information. If no one knows what you’re asking, you won’t get any response (and we probably won’t print it either).

• Write legibly (or type). If we can’t read it, we’ll throw it away.

• Include your Name, Address, Phone Number, and Email. Only your name, city, and state will be published with the question, but we may need to contact you.

[6041 - June 2004]

Does anyone know how I might construct a relatively simple field strength meter to orient a UHF antenna while I’m perched on a ladder? The circuit would be tuned to one specific frequency — say 500 MHz.