Nuts & Volts - September 2004

Q&A

then run inside a fan, based on a self-timer. Yet again, you ignored my request!

Now, I have this audio frequency amplifier (Please, don’t ask me what it’s for!) with all the parts for it, but I’ve forgotten which part goes where. Can you please help me find the accurate values for caps and resistors from the parts list given. My JPEG image doesn’t contain viruses!

you the answer or flip it over to the Tech Forum. Be aware, though, I can’t answer a question that takes all of my time or uses up my month’s allotment of ink. For that, we have feature articles. So, don’t expect me to build your science project or write your thesis.

Hopefully, I will soon have a Nuts & Volts “Q & A” web page for those spill-over questions that didn’t make the cut for the magazine, but need answering. Stay tuned.

this site for Heath Robot owners (I have a Hero Jr.): http://hero.dsav age.net

Richard Ober Baton Rouge, LA

Also try http://ww_heco. home.mindspring.com/ It keeps better track of the moving Heath websites than I can.

— TJ

D. Zillbermann via Internet

MAILBAG

A. I never ignored your requests and even responded to at least one via Email. The problem is that your questions either require more page space than this column affords or that they are too ambiguous or application specific. As for the Linx Technologies question, did you ever check their website? It has your answers.

If other readers feel like Mr. Zillbermann — in that I’m ignoring you — please realize that I receive more questions per month than I can possibly publish. I have to select those questions that appeal to the greater audience. If your question has to be bumped, I do my best to Email

Dear TJ,

I have been rummaging through my back copies of Nuts & Volts, looking for a schematic that you might have been a part of. In doing so, I noted a Mailbag entry in the October 2003 issue from Joseph Wilson suggesting that a particular Heath site did not exist.

Being old enough to have built these kits, I looked for the site and found it at www.circuitarchive. fsnet.co.uk/heath.htm (It may take a few tries to access the site; it is available intermittently.) The URL in the magazine left out FSNET.

Plus, in surfing around, I hit upon

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Dear TJ,

Regarding the February 2004 issue, the concept of a 42 volt system (actually 36 volts) is not really new. Back in the 1920s and 1930s, 36 volt lighting systems were used in many railway passenger cars and in rural America where there were, as yet, no commercial power lines. The lamps were designed to operate at 32 volts and looked like ordinary household lamps with the standard Edison screw base and fitted ordinary 110 volt-type sockets. This concept was wonderful for its time.

While it’s true that a higher voltage system in an automobile will allow smaller and lighter wiring to be used, there is a potential problem. The wire used on a 36 volt system may need only 1/3 the cross-sectional area of the equivalent 12 volt system, but — in Canada and the northern US — this thinner wire can be susceptible to disruptive corrosion caused by road salt used in the winter to clear the roads.

The problem with corrosion usually is not along the length of the wire, which is insulated, but at the point the wire terminates, where the copper is exposed. Unless the auto makers take much greater care in design and installation to protect these smaller wires than they currently do, there will be a rash of various kinds of automotive electrical system failures long before their time.