DC cigarette lighter adapter power surges when running engine
oldfarmer
Can anyone tell me how much danger of power surge there would be using a
DC car cigarette lighter adapter running at 9volts/900milliamps but capable
of 12volts/3amps when starting the car engine? The item is from Radio Shack
and has a fuse in it so I assume it has some surge protection, I'll have to
check the fuse. Anyway I'm going to be using this item with a Drake SW8 and
I will periodically need to start the car and drive around a little and I'm
wondering if I should pull the adapter out of the socket while
starting/running/driving the car or whether it's safe to leave it in. Thanks
for the help.
Speaker to Animals
oldf...@earthlink.net says...
overload. But I doubt is such a cheap device has any real "surge protection".
I use an over-voltage (AKA Crowbar) on ALL my automotive applications.
On the +12 (+13.6 to +15 engine running) the "crowbar (SCR and active zenar)
is set to calmp at 15.2V. I also have an inductor series, with a fairly large
capacitor (10,000uf +1uF tant) in parallel to snub out real narrow pulses.
With a diode to clamp all reverse pulses. Running automobiles are nasty
elctrical systems. Very dirty. Especially when starting. Imagine what spikes
you get from a 100Amp 12V motor!
The simple, and safest solution is to disconnect the adaptor wehn running the
engine. The military, as part of normal operating procedure, turns off all
radio when starting vehicals. Look in any ARRL handbook for ideas on a crowbar
style clamp. ASCII is not up to posting such a diagram.
Good listening!
oldfarmer
say this crowbar is some homebrew surge protector for use while the car is
running?
"Speaker to Animals" <Dante'@inferno.net> wrote in message
news:9fefat$7dv$3...@news.uky.edu...
Speaker to Animals
oldf...@earthlink.net says...
>
> As I suspected, yea that's what I've been doing for the time being. You
>say this crowbar is some homebrew surge protector for use while the car is
>running?
>
the SCR conducts and shorts the +12 to ground, like a "crowbar".
A freind lost the voltage regulator on the way home from a camping trip. It
fried all of the stock auto electroincs. Ignition, lights, and fuel pump.
But his addon radio gear was ok. Which was very nice becasue he could shout
for help on his ham 2mtr. Made a beleiver out of me, and I have always
protected my gear since his smoking experience.
Radio quit working when you let the smoke out!(G)
callin fer ice cream
"oldfarmer" <oldf...@earthlink.net> wrote in message
news:7XvS6.17342$651.1...@newsread1.prod.itd.earthlink.net...
> Hello,
>
> Can anyone tell me how much danger of power surge there would be using a
> DC car cigarette lighter adapter running at 9volts/900milliamps but capable
> of 12volts/3amps when starting the car engine?
Switch the radio OFF when starting or shutting off the engine.
Older cars were worse, but I've seen nasty spikes on a scope
from even newer (98 Toyota) cars. Until the alternator is up to
speed and the starter motor is out of the circuit, inductive spikes
and regulator indeterminate states are very possible. Most stock
auto car radios have a crowbar or other sense circuit to catch this
and cut power to the radio whenever the start is engaged.
Hondas have a nifty circuit that does not restore power to their stock
radios until 1-2 seconds after starting the car. (turn on the auto
broadcast radio with the key in acc, when it's playing, start the motor
and you should see the auto radio cut out just before you start the
engine and come up a second or two after releasing the key. A nifty
circuit to reproduce for use with mobile swl accessories Check the
auto schematics)
oldfarmer
adapter while the engine is not running right?
"oldfarmer" <oldf...@earthlink.net> wrote in message
news:7XvS6.17342$651.1...@newsread1.prod.itd.earthlink.net...
Speaker to Animals
oldf...@earthlink.net says...
>
>Well for the time being then it's at least safe to run the radio off the
>adapter while the engine is not running right?
>
>
devices, but a step down voltage regulatro is hardly rocket science.
Be sure to feel the converter after it has been on for several minutes. If it
gets too hot to comfortably touch, you might want to reconsider using it.
Bullheaded
so all should be well. On the other hand, this is from Radio Shack so they might have
left out a zener diode because they are so cheap.
"oldfarmer" <oldf...@earthlink.net> wrote in message news:YtbT6.8608$bZ6.1...@newsread1.prod.itd.earthlink.net...
w_tom
www.aaeon.com .