Pro-96 External Power

[baybum]

The book says 9VDC. Has anyone used direct 12VDC fron the vehicle to power/charge this radio?
Is there an internal voltage/current regulator to protect against overcharging/overheating?

I have a 9VDC cigarette lighter adapter from Radio Shack and there's alot of humming and whining in the radio. And when I connect an external computer speaker, running off 12VDC, it
whines even louder and is un-readable.

I'd like to come straight off the battery to the radio.

Thanks,

Mike

 

[bwhite]

This discussion has occurred on a few other threads a way back, Uniden threads I believe.
Their 235 & 245s use 4 AA batts yet you can plug direct into the lighter, there is no apparent inductor to reduce voltage and all seems OK. Sounds like you may be in a similar situation except for the audio mess, I don't know what to say about that. Question though, does it whine like this in other vehicles? I'm thinking you might have an alternator or other device on the one vehicle that is putting off alot of RF and messing up the scanner.

 

[baybum]

Thanks, but I don't think I want to experiment with my Pro-96 based on Uniden data.
The whining noise occurs in two different vehicles.

But the noise aside, I'd still like to get rid of the cigarette lighter option and come right off the battery if possible.

 

[bwhite]

The cig lighter is direct 12v but I think you are saying that you want to put a plug right from one of the car's 12v systems to the radio's ext pwr plug. I'm guessing that it runs quiet with the motor off and then kicks in when the engine is on ? Does it change pitch when the motor speed changes?
It may just be that the radio has poor shielding, I don't know. I think I saw you with a similar post in the RS threads, you'll probably get better advice there from other owners.

 

[baybum]

The cig lighter is 12VDC but the adapter is switchable, 6, 9, 12VDC. I have it set for 9.
The volume on the radio, throught the external speaker is rduced 80% when using the adapter and the 12VDC external speaker. Weather the motor is running or not.
I thought I'd post it here because I wasn't getting any response on the national RS thread.
I can always count on my local scannists for some advice.

My basic question remains...can you put 12VDC directly into the scanner without fear of overcharging?

Mike

 

[bwhite]

In my experience whine if from the motor, that's why I asked about the sound when the motor is off.
Get out your volt-ohm meter and check the voltage coming directly out of your power supply that came with the radio (if it is the wall-wart kind) and see what the voltage is, it may surprisingly be up near 12 meaning you can try the same in the car.

 

[turbo77577]

Car battery voltage

car's voltage with key off is 12.5 or a little lower. running could be 13.4 to 14.9 verys on battery & rpm. of motor.

 

[Llwellyn]

This noise can be fixed by something like this:

http://www.crutchfield.com/S-baTLSfkvjEe/cgi-bin/ProdView.asp?g=890&I=127ANS80

Usually, the alternator is the offender.

Also, it could be caused by the cigarette lighter being improperly grounded; you may need to find a DC9V power supply that is shielded against noise. Usually, the adapters that come with scanners have the proper shielding, but a scanner that didn't come with a DC adapter leaves you with problems if you get an unshielded adapter.

EDIT: You might also want to look for a ground loop isolator (which is what I was referring to being built into some adapters above, I just didn't have the right name). The more stuff you have hooked into the 12V line the worse it gets across all the equipment.

 

[kc4jgc]

The cig lighter is 12VDC but the adapter is switchable, 6, 9, 12VDC. I have it set for 9.
The volume on the radio, throught the external speaker is rduced 80% when using the adapter and the 12VDC external speaker. Weather the motor is running or not.
I thought I'd post it here because I wasn't getting any response on the national RS thread.
I can always count on my local scannists for some advice.

My basic question remains...can you put 12VDC directly into the scanner without fear of overcharging?

Mike

Wiring directly into the car battery won't charge the scanner battery pack at all because you will FRY the scanner seconds after plugging it in. If you can step the voltage down to 9v before entering the scanner then yes.

I have a cigarette lighter plug from RS thar steps the car voltage down to 9v. I have no problem with alternator whine. It is not voltage adjustable. If your problem is not alternator whine (you haven't ruled it out yet), perhaps there's aproblem with your multi-voltage adapter (grasping at straws here)?

 

[trimmerj]

Get a lighter plug and build a 9volt regulator box. Find a 7809 voltage regulator, put a 1000uF capacitor across the 12vdc input and ground and 100uF across the 9 Volt output and ground. Put it all in a small project box from rat shack. Use a multimeter to make sure you have the right polarity on each end. Will eliminate any alternator whine.

 

[bwhite]

Going way back in these discussions on the 1 of the 2 topics he inquires about,
Many radios will take significantly higher voltages (like the 235/245 from uniden that
have 4 AA batteries but run fine off a cig lighter). He is correct to be concerned about the
welfare of his radio though, I'd step it down to whatever normally comes out of his wall wart
(which may be significantly higher than 9v)

 

[baybum]

Many thanks

To all for your replies. We can put this one to bed now.
I think Lou nailed it. If this radio has no voltage/current regulator, or protection circuit, there's no way I'll connect 12VDC up to it from my truck.

Mike

 

[RyanXTS]

I run my pro-95 off of 6vdc cd-player adaptors. Works great!