From: David Lesher
Subject: Re: (Avionics) How can this circuit produce an "inductive surge"?
Date: Sat, 28 Sep 2002 14:45:07 +0000 (UTC)
Organization: NRK Clinic for habitual NetNews Abusers - Beltway Annex
References: <firstname.lastname@example.org> <email@example.com>
Reply-To: firstname.lastname@example.org (David Lesher)
NNTP-Posting-Date: Sat, 28 Sep 2002 14:45:07 +0000 (UTC)
Iwo Mergler writes:
>The one which annoys me, is the bit about cellphones in petrol
>stations. Why aren't you supposed to *talk* on them? There is
>no difference in radiation between talking and having a call
>comming in. Yet having them switched on is allowed, talking is
History. In days long past, the 2000 VDC for the plates of the tubes
in the final amp  of the 2-way radio in the police car trunk...
that HV came from a "dynamotor" -- a 12v^H^H 6V DC motor not much
smaller than a starter & a 2000 VDC generator, all on one shaft.
Push the XMIT button, a large relay closed and a whinNNNNE... came
from the trunk.... as the engine slows down under the sudden 100amp
load. Then and only then you talk into the mike. Please be brief.
Your battery thanks you.
Now, as you might imagine, that dynamotor makes lots of sparks.
If your trunk has any fumes from the gas you just pumped, oops.
I recall a picture of a 50's Mopar Police Special lacking a trunk
lid, as it had ...departed... the vehicle suddenly.
BTW, WWII ARC-5's, BC-453's and other aircraft radios also had
dynamotors. If you ever wondered why a B-17 was so heavy before you
Now, we don't have dynamotors anymore. So that's not an issue. But
memory lingers. And I suppose there's a new reason; if you are
babbling on your yuppiephone, you are not noticing that the pump
shutoff didn't, and 91 Octane is spilling all over the ground.
"2150 to Headquarters..."
[1: see a history book if you don't know those terms...]