It used to cut out immediately when I would turn the key back...I put in a CB radio, wired to the fuse block on the same fuse as the radio, but today my radio stayed on for a good 30 seconds after the key was removed...why is this? Doesn't make any sense...thanks!

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'89 RS LO3- 140,000 miles
14x3 K&N Open Element
Ram Heavy Duty clutch
Edelbrock TES (Jet-hot coated)
Catco cat
Edelbrock 3" Cat-back
Pioneer DEH-P77
Dual .50 caliber machine guns just under ground effects

Coming:
KYB shocks
Edelbrock Strut Tower Brace
South Side Machine subframe connectors

When your buddy reaches for a 10-pound sledge and says "I think we're gonna have to modify the floor pan, okay?" the answer is NO.

 

Anybody?

 

Is this the first and only time or is it doing again and again, if it's a one time deal don't worry about it, check your wiring, did you wire your CB up and mix up the "Always hot" and "Ignition On" wires.

 

Definitely didn't mess up the wiring...this is the first time...it's like there was juice left in the system, but lately it's been behaving, so I won't complain...but I'll keep you posted. Thanks for the reply.

 

Hmmm. One would suspect back-EMF from a motor shutting down somewhere. I have that problem, because of the way I wired my secondary electric fan, if it's on when I shut the car off the blower motor will run on for a few seconds.

 

I guess I committed the ultimate sin by giving the wrong advice, seeing as how my post was picked apart to prove me wrong, so I deleted what I wrote. This better?
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DR Stevens
1984 Trans Am 305HO L69
1991 Firebird 305 L03

[This message has been edited by eightTfourTA (edited June 09, 2001).]

 

A 30 second back EMF?

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-Jason M. 1991 Camaro Z28

[This message has been edited by Jason M 91Z (edited June 09, 2001).]

 

Perhaps we've come stumbled across an alternate energy source.............

 

HAHA, aww damn. Maybe all you CA residents should get power inverters, plug them into the cig. lighter, and back feed the panel in your house. If you just start your car, leave your CB on, and then shut it off, you can watch TV for 30 seconds!

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-Jason M. 1991 Camaro Z28

 

.

[This message has been edited by eightTfourTA (edited June 09, 2001).]

 

OK, I will contribute my veritable answer.

Assuming the cause is back EMF, which may in fact be, diode isolate your CB using some 3A bridge rectifier diodes available from RatShak. That will prevent your CB from backfeeding other accessories. If you switch to a different accessory circuit, you will only be backfeeding the devices on that circuit, i.e. wipers or heater controls. Even worse is it could backfeed your ignition circuit.

P.S., Is that better Doc?

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-Jason M. 1991 Camaro Z28

[This message has been edited by Jason M 91Z (edited June 09, 2001).]

 

Hey, those guys on the "left coast" will surely appreciate it. I think someone is gonna get awfully rich on this one!

(I'm still laughing...)

Hey, in all seriousness (and I can't believe that you're still going to maintain your position), there is no way in .... uuuuh, I mean no way that a CB radio or any other device commonly used in an automotive environment is going to be capable of powering a radio "for a good 30 seconds" just based on a residual charge from its internal electronics. UNLESS, of course, you've got a capacitor about the size of a 55 gallon barrell inside that CB!!!!!

What you are failing to understand is that the stored energy (more than likely in a capacitor(s)) IS NOT UNDER LOAD. The "load" in this case is the radio which continues to be powered for a GOOD 30 seconds!

I would agree that stored energy (from capacitance or a DC motor continuing to rotate) could continue to power the radio after power is removed, but anything longer than one second (and one second is being very generous) would just not be in the realm of reality.

For example, when I turn a radiator fan off, it will continue to rotate for ~5 seconds. Since it's a DC motor, it will act like a generator, and generate electricity until it stops rotating. I have a L.E.D. connected to the power wire of this motor (so I know when the fans are operating). When I remove power to the fan, this L.E.D. will continue to illuminate for ~3 seconds (maybe 4 or 5), initially at an intensity of ~75%, but toward the end of this time period, the intensity will be EXTREMELY dim. The L.E.D. will present a 25mA (0.025 ampere) load to this "generator", and although I've never actually measured the current being produced by the fan continuing to rotate, I'd estimate it to be ~10mA (0.010 ampere) at ~7 volts, rapidly tapering off to zero volts in <4 seconds just based upon the intensity of the L.E.D. during the time the fan continues to rotate.

Now, lets see, how much current will a radio require? One ampere is typical. That's 1000mA.


And remember, Baron's radio continued to be powered for a good 30 seconds.

I disagree.

Guilty as charged. But, but, but, but, it was soooo funny, especially the California part.... I'm sorry, I just couldn't help myself. I'm still chuckling.

[This message has been edited by Stuart Moss (edited June 09, 2001).]

 

Stuart, is the patent office still open? Maybe we can go find 20-30 old tube driven CB's and make a power cell. We can run car radios all day!

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-Jason M. 1991 Camaro Z28

 

Jason,

That's funny. But actually, I've got all the business I can handle with the hugh demand for all of the ocean front property I'm selling in Kansas.

 

Haha, what a night! From CS130D's to the next generation power cell to Kansas's oceanfront property! :-)

BTW, he's right, 9-12VDC can really give you a good jolt. I've been an electrician for 6 years and thought 277VAC hurt, but now that he mentions it, DC tends to hold you while AC tends to throw you. Watch out for those intense square waves present in your CB radio!

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-Jason M. 1991 Camaro Z28

 

Well, touching both the positive and negative battery terminals of an automotive battery (12 volts at several hundred amperes) generally will not do anything. But I wonder what will happen when you repeat the same procedure with an open wound (preferably with blood) on both left and right hands.

Less voltage? Ok, touch both terminals of a 9 volt battery. Nothing? Ok fine. Try touching your tongue to both terminals of a 9 volt battery. This I've done (may explain a lot things about me). While I didn't get a "shock", I did get a "tingle". And that's sort'a-kind'a like a shock.

I used to fool kids when I was in Central America by asking them to touch the secondary wire of the HEI ignition transformer (AKA coil) when I had it out on a test bench with only a 1.5 volt battery. I'd say "...see, how can you get a shock from only a 1.5 volt battery....no way...". And so they'd touch the secondary wire while making and breaking contact with the primary side of this coil to the 1.5 volt battery. I used to have great fun playing with high voltage.

I guess I've got an evil streak, uh?

CYA

 

Stuart Moss, I beg to differ on your comment about a small cap being able to run a head unit for no more than 1 second. I installed an inline noise supressor and it's basically just a cap the size of 2 golf ***** lined up, no bigger and no heavier. The head unit stays on for a good 10 to 15 seconds then turns off. This was with my older panasonic head units (one broke and other 2 were stolen). I did have a relay on the remote turn on lead to the amps but I can bet right now $50 that I can do it again. Anybody want to take me up on this?

 

I have seen quite a few old panasonic cd players that were designed to stay on for a little while after the car was shut off.