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12V DC mobile power supply (battery pack)
I have been looking on google and can't find anything on this subject.
I want to take a mobile CB radio, designed to run off of a 12 volt power line in an automotive vehicle, and convert it to run on 9V, C, or D cell batteries so I can put it in a backpack and take it with me when I go on long hikes away from home and the like, and talk back to a base station in the house. Would it be as simple as connecting a bunch of batteries together in circuit and using a resistor (or series of resistors) to lower the current (if too high), or using an amplifier to raise it? I have some basic electronics books on these subjects (basic, basic digital, and basic communications electronics books from radio shack), but I wanted to get some input before I went and tried to do something and blew up my radio. :-) Would this be possible using the methods I described? Would I need other methods? Or would I just need to give it up and try something else? (Also, does anyone know where I might find information about changing the frequencies the radio runs on? If I could find a way to make it run on the same frequencies as some smaller GMRS radios I have, that'd be awesome... but from what I understand it would probably require changing the entire guts of the radio... so if that's not feasible don't worry too much about it. :-) Thanks alot in advance |
#2
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12V DC mobile power supply (battery pack)
On Sun, 18 Apr 2004 13:48:26 -0500, Andrew Kesterson wrote:
I have been looking on google and can't find anything on this subject. I want to take a mobile CB radio, designed to run off of a 12 volt power line in an automotive vehicle, and convert it to run on 9V, C, or D cell batteries so I can put it in a backpack and take it with me when I go on long hikes away from home and the like, and talk back to a base station in the house. If you really must.... ;-) Would it be as simple as connecting a bunch of batteries together in circuit and using a resistor (or series of resistors) to lower the current (if too high), or using an amplifier to raise it? You can use NiCd or NiMH cells wired in series to give the required voltage. Both of these are 1.2v per cell, so a 12v supply would need 10 cells. The portable CB radios tend to use the AA size, but Cs or even Ds are ok if you don't mind the extra weight and cost! Whatever you do, *please* fit a little fuse adjacent to the battery pack - especially if using NiMH cells as these can easily give enough current on a short circuit to be dangerous. Don't attempt to modify the internals of the CB at all. Just provide 12v. You could also use a sealed lead-acid battery of course. You will probably have a high/low power switch on the CB. Use low power whenever possible. It will lengthen your talk time appreciably. It is also rather unwise to use high power when you are using a little rubber aerial a few inches from your head! I have some basic electronics books on these subjects (basic, basic digital, and basic communications electronics books from radio shack), but I wanted to get some input before I went and tried to do something and blew up my radio. :-) Would this be possible using the methods I described? Would I need other methods? Or would I just need to give it up and try something else? (Also, does anyone know where I might find information about changing the frequencies the radio runs on? If I could find a way to make it run on the same frequencies as some smaller GMRS radios I have, that'd be awesome... but from what I understand it would probably require changing the entire guts of the radio... so if that's not feasible don't worry too much about it. :-) No - two reasons. First, its illegal. Second, it needs careful setting up with specialised test gear just to move the frequency a little. They just won't go into the GMRS band - and wouldn't communicate with them even they did! If the range of a GMRS is sufficient you would be better using one of those anyway. Follow-ups set to alt.electronics -- Cheers... Mick Gave up on viruses & trojans - moved to Linux... :-) Nascom & Gemini info at http://www.nascom.info |
#3
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12V DC mobile power supply (battery pack)
"Andrew Kesterson" wrote in message
news I have been looking on google and can't find anything on this subject. I want to take a mobile CB radio, designed to run off of a 12 volt power line in an automotive vehicle, and convert it to run on 9V, C, or D cell batteries so I can put it in a backpack and take it with me when I go on long hikes away from home and the like, and talk back to a base station in the house. Would it be as simple as connecting a bunch of batteries together in circuit and using a resistor (or series of resistors) to lower the current (if too high), or using an amplifier to raise it? I have some basic electronics books on these subjects (basic, basic digital, and basic communications electronics books from radio shack), but I wanted to get some input before I went and tried to do something and blew up my radio. :-) Would this be possible using the methods I described? Would I need other methods? Or would I just need to give it up and try something else? (Also, does anyone know where I might find information about changing the frequencies the radio runs on? If I could find a way to make it run on the same frequencies as some smaller GMRS radios I have, that'd be awesome... but from what I understand it would probably require changing the entire guts of the radio... so if that's not feasible don't worry too much about it. :-) Thanks alot in advance About 20 years ago, I was doing the same thing with UK CB radios. If I remember correctly, I was modding the tiny (and crappy) Maxon 21E with 10 x AA NiCads in a holder on its back.. Gave around 13 Volts and lasted quite well. I used and external telescopic aerial with either a center or base loaded coil (depended on what was available). I think Midland also made a similar commercial set to this. You could also try a small 12Volt Gel Cell. Cheers. Mark. |
#4
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12V DC mobile power supply (battery pack)
"Andrew Kesterson" wrote in message .. .
I have been looking on google and can't find anything on this subject. I want to take a mobile CB radio, designed to run off of a 12 volt power line in an automotive vehicle, and convert it to run on 9V, C, or D cell batteries so I can put it in a backpack and take it with me when I go on long hikes away from home and the like, and talk back to a base station in the house. Would it be as simple as connecting a bunch of batteries together in circuit and using a resistor (or series of resistors) to lower the current (if too high), or using an amplifier to raise it? You could not get a voltage higher than what you have from the batteries, so the amplifier cannot be used. You need 12 volts or higher from the batteries, because there's probally a good reason the radio runs on 12 volts. If you had a voltage higher than 12 volts, you could use a 12 volt regulator, but not resistors. The radio is non-linear, and changes resistance based on whether or not it's being used, so a regulator is needed. You might want to see how much current the radio draws, and buy a 12 volt regulator higher than your maximum current rating. If you are using a source slightly higher than 12 volts, than you need a minimum voltage dropoff rating on the regulator of the difference between the battery voltage and 12 volts. I have some basic electronics books on these subjects (basic, basic digital, and basic communications electronics books from radio shack), but I wanted to get some input before I went and tried to do something and blew up my radio. :-) Would this be possible using the methods I described? Would I need other methods? Or would I just need to give it up and try something else? (Also, does anyone know where I might find information about changing the frequencies the radio runs on? If I could find a way to make it run on the same frequencies as some smaller GMRS radios I have, that'd be awesome... but from what I understand it would probably require changing the entire guts of the radio... so if that's not feasible don't worry too much about it. :-) I believe this is possible, and inexpensive, but I'm not sure how you would do this. You would have to desolder either a crystal or a capacitor, then solder on another one. Both componants are under a dollar. Thanks alot in advance |
#5
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12V DC mobile power supply (battery pack)
"Andrew Kesterson" wrote in message .. .
I have been looking on google and can't find anything on this subject. I want to take a mobile CB radio, designed to run off of a 12 volt power line in an automotive vehicle, and convert it to run on 9V, C, or D cell batteries so I can put it in a backpack and take it with me when I go on long hikes away from home and the like, and talk back to a base station in the house. Would it be as simple as connecting a bunch of batteries together in circuit and using a resistor (or series of resistors) to lower the current (if too high), or using an amplifier to raise it? 8 1.5V batteries will give you 12V (C or D), the circuit will draw the amperage it needs (probably more than you want, considering battery life). You might consider buying one of those handy talky type radios which are designed to run on batteries. I have some basic electronics books on these subjects (basic, basic digital, and basic communications electronics books from radio shack), but I wanted to get some input before I went and tried to do something and blew up my radio. :-) Would this be possible using the methods I described? Would I need other methods? Or would I just need to give it up and try something else? (Also, does anyone know where I might find information about changing the frequencies the radio runs on? If I could find a way to make it run on the same frequencies as some smaller GMRS radios I have, that'd be awesome... but from what I understand it would probably require changing the entire guts of the radio... so if that's not feasible don't worry too much about it. :-) Sure its possible, its also illegal and harder than just getting a ham radio license and then getting a lot more range by applying good antenna designs to a good ham band radio. |
#6
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12V DC mobile power supply (battery pack)
IS it illegal?? Both FRS and CB bands are open....no license required!
It's the transmit power that's the regulated portion of each (5W for CB and not sure for FRS). If he's thinking of FRS then dump the CB idea....traffic seems to be getting less and less all the time (just the odd trucker looking for a good place to chow!). "Form@C" wrote in message news On Sun, 18 Apr 2004 13:48:26 -0500, Andrew Kesterson wrote: I have been looking on google and can't find anything on this subject. I want to take a mobile CB radio, designed to run off of a 12 volt power line in an automotive vehicle, and convert it to run on 9V, C, or D cell batteries so I can put it in a backpack and take it with me when I go on long hikes away from home and the like, and talk back to a base station in the house. If you really must.... ;-) Would it be as simple as connecting a bunch of batteries together in circuit and using a resistor (or series of resistors) to lower the current (if too high), or using an amplifier to raise it? You can use NiCd or NiMH cells wired in series to give the required voltage. Both of these are 1.2v per cell, so a 12v supply would need 10 cells. The portable CB radios tend to use the AA size, but Cs or even Ds are ok if you don't mind the extra weight and cost! Whatever you do, *please* fit a little fuse adjacent to the battery pack - especially if using NiMH cells as these can easily give enough current on a short circuit to be dangerous. Don't attempt to modify the internals of the CB at all. Just provide 12v. You could also use a sealed lead-acid battery of course. You will probably have a high/low power switch on the CB. Use low power whenever possible. It will lengthen your talk time appreciably. It is also rather unwise to use high power when you are using a little rubber aerial a few inches from your head! I have some basic electronics books on these subjects (basic, basic digital, and basic communications electronics books from radio shack), but I wanted to get some input before I went and tried to do something and blew up my radio. :-) Would this be possible using the methods I described? Would I need other methods? Or would I just need to give it up and try something else? (Also, does anyone know where I might find information about changing the frequencies the radio runs on? If I could find a way to make it run on the same frequencies as some smaller GMRS radios I have, that'd be awesome... but from what I understand it would probably require changing the entire guts of the radio... so if that's not feasible don't worry too much about it. :-) No - two reasons. First, its illegal. Second, it needs careful setting up with specialised test gear just to move the frequency a little. They just won't go into the GMRS band - and wouldn't communicate with them even they did! If the range of a GMRS is sufficient you would be better using one of those anyway. Follow-ups set to alt.electronics -- Cheers... Mick Gave up on viruses & trojans - moved to Linux... :-) Nascom & Gemini info at http://www.nascom.info |
#7
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12V DC mobile power supply (battery pack)
On Tue, 20 Apr 2004 00:23:34 +0000, SB wrote:
IS it illegal?? Both FRS and CB bands are open....no license required! It's the transmit power that's the regulated portion of each (5W for CB and not sure for FRS). Yep, the restrictions are on the radiated power, frequency band and modulation modes. OK, so may be *possible* to change any or all of these but you arn't going to do it and keep the equipment legal unless you can set it up correctly. You arn't going to do that without the proper test equipment! It is one thing to change a crystal but something else to *prove* that the new one or the coil tweaks needed to make it work arn't introducing harmonic signals all over the band. Whether it is economically feasible to make the mods is something else... :-) I haven't looked at the radio regs for a long time, but at one time I think it atually *was* illegal to make modifications to a CB rig. They were type-tested and certified - carrying the CB/27 symbol. Any mods meant that the certification was automatically lost, making them illegal. There are probably still clauses like this as well as those limiting the type of aerial that can be connected (restricting the erp). If he's thinking of FRS then dump the CB idea....traffic seems to be getting less and less all the time (just the odd trucker looking for a good place to chow!). Dunno. I gave up on CB many years ago - before I took my RAE. Sounds like the OP only wants a radio link back to base so it probably doesn't matter which he uses providing he can get enough range. -- Cheers... Mick Gave up on viruses & trojans - moved to Linux... :-) Nascom & Gemini info at http://www.nascom.info |
#8
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12V DC mobile power supply (battery pack)
Well, you don't often hear about guys being pulled over at CB checkpoints!
It's one of those things that isn't enforced until it HAS to be. So basically, if mods made to a radio DON'T interfere with someone then I doubt you'll hear otherwise. There's plenty of Ham radio guys that build their own radio that don't have to get it certified....however, those bands are all based on etiquette. As far as poor mods....well, I wouldn't call it a mod if nobody else can hear you cuz your mod is killing your signal (bad quality/etc.). I have an old airband radio (ex SAR guy gave it to me) and he had it "opened" up. This didn't let me transmit on any extra bands, but it did let me listen to a lot more...basically turned it in to a scanner.... At work, we're expecting some issues with US wireless LANs interfereing with our transmitters. The Canadian made LAN equipment has provisions to keep out of our band, but being so close to the US allows easy importing of equipment that will drop on us in the band. We're lucky at the moment that we're out in the boonies but will have issues in our suburban equipment. We've made our complaints and the FCC/Industry Canada are checking things....but if nobody complains it's not a big deal. "Form@C" wrote in message news On Tue, 20 Apr 2004 00:23:34 +0000, SB wrote: IS it illegal?? Both FRS and CB bands are open....no license required! It's the transmit power that's the regulated portion of each (5W for CB and not sure for FRS). Yep, the restrictions are on the radiated power, frequency band and modulation modes. OK, so may be *possible* to change any or all of these but you arn't going to do it and keep the equipment legal unless you can set it up correctly. You arn't going to do that without the proper test equipment! It is one thing to change a crystal but something else to *prove* that the new one or the coil tweaks needed to make it work arn't introducing harmonic signals all over the band. Whether it is economically feasible to make the mods is something else... :-) I haven't looked at the radio regs for a long time, but at one time I think it atually *was* illegal to make modifications to a CB rig. They were type-tested and certified - carrying the CB/27 symbol. Any mods meant that the certification was automatically lost, making them illegal. There are probably still clauses like this as well as those limiting the type of aerial that can be connected (restricting the erp). If he's thinking of FRS then dump the CB idea....traffic seems to be getting less and less all the time (just the odd trucker looking for a good place to chow!). Dunno. I gave up on CB many years ago - before I took my RAE. Sounds like the OP only wants a radio link back to base so it probably doesn't matter which he uses providing he can get enough range. -- Cheers... Mick Gave up on viruses & trojans - moved to Linux... :-) Nascom & Gemini info at http://www.nascom.info |
#9
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12V DC mobile power supply (battery pack)
On Tue, 20 Apr 2004 22:08:50 +0000, SB wrote:
Well, you don't often hear about guys being pulled over at CB checkpoints! It's one of those things that isn't enforced until it HAS to be. So basically, if mods made to a radio DON'T interfere with someone then I doubt you'll hear otherwise. ....probably 'cos you have either got it set right or are running such low power that no-one can hear you. :-) There's plenty of Ham radio guys that build their own radio that don't have to get it certified....however, those bands are all based on etiquette. They are also based on learning how to set the gear up, and what to test for. It isn't all that easy to build a transmitter that is legal. Even the amateurs get into a lot of trouble if they don't set their gear up properly! Many years ago we used to get away with all sorts of lash-up valve transmitters, but with increasing demands on bandwidth - and a lot of commercial people that begrudge the amateurs *any* space at all - it has become far more important to keep the transmitters as "clean" as possible. As far as poor mods....well, I wouldn't call it a mod if nobody else can hear you cuz your mod is killing your signal (bad quality/etc.). LOL! - not a very effective mod either... I once did a mod on an old CB rig to move it into the 28MHz band. It worked, but as I was never able to check it properly for transmitted harmonics, it has spent almost all it's modded life disconnected! It wasn't helped that my licence didn't cover 28MHz at the time anyway... ;-) I have an old airband radio (ex SAR guy gave it to me) and he had it "opened" up. This didn't let me transmit on any extra bands, but it did let me listen to a lot more...basically turned it in to a scanner.... That should be ok. The receiver section doesn't cause problems (in most cases - before someone mentions TRFs!) At work, we're expecting some issues with US wireless LANs interfereing with our transmitters. The Canadian made LAN equipment has provisions to keep out of our band, but being so close to the US allows easy importing of equipment that will drop on us in the band. We're lucky at the moment that we're out in the boonies but will have issues in our suburban equipment. We've made our complaints and the FCC/Industry Canada are checking things....but if nobody complains it's not a big deal. Looks like you could be having some fun there... I bet there will be some complaints of corrupted or insecure data before long. -- Cheers... Mick Gave up on viruses & trojans - moved to Linux... :-) Nascom & Gemini info at http://www.nascom.info |
#10
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12V DC mobile power supply (battery pack)
js_530 wrote:
"Andrew Kesterson" wrote in message .. . I have been looking on google and can't find anything on this subject. I want to take a mobile CB radio, designed to run off of a 12 volt power line in an automotive vehicle, and convert it to run on 9V, C, or D cell batteries so I can put it in a backpack and take it with me when I go on long hikes away from home and the like, and talk back to a base station in the house. Would it be as simple as connecting a bunch of batteries together in circuit and using a resistor (or series of resistors) to lower the current (if too high), or using an amplifier to raise it? You could not get a voltage higher than what you have from the batteries, so the amplifier cannot be used. You need 12 volts or higher from the batteries, because there's probally a good reason the radio runs on 12 volts. If you had a voltage higher than 12 volts, you could use a 12 volt regulator, but not resistors. The radio is non-linear, and changes resistance based on whether or not it's being used, so a regulator is needed. You might want to see how much current the radio draws, and buy a 12 volt regulator higher than your maximum current rating. If you are using a source slightly higher than 12 volts, than you need a minimum voltage dropoff rating on the regulator of the difference between the battery voltage and 12 volts. ´ "12V" in a car ís at least 13.6V, and the CB will probably survive 15 v or so at least. Leif |
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