As long as you are going down in voltage, there are relatively simple analog circuits that can drop the voltage to anything you might want. While you can use a simple dropping resistor, this only works if there is a known steady current draw and you design for that draw and you have some risk under no load where the voltage could damage the device.
You could use a standard 78xx series three terminal regulator design. This would only require a couple of capacitors and a resistor or two. For example, when HT's first became popular, they often did not work directly on 13.8 VDC and had to have some kind of controller. The ICOM IC-2AT actually used a slide on pack, which looked like a small battery pack, but was a simple controller to drop the voltage down to a safe 9.6 VDC for proper operation of the HT. You are probably aware that you will have to dissipate the current from the voltage drop that you don't want. This would mean some substantial inefficiencies when you have to drop quite low as you would with 1.5 or 3 volts. The only reason that I would do this is so that I could operate on battery power. It might be better to run those devices on a separate battery pack at their native voltage requirement. Needless to say, we have to be very careful with these kinds of devices so that we don't accidentally plug the wrong power level into the device. I converted everything in my shack, vehicles, and portable equipment to Anderson Powerpoles and I attempt to run most things on 13.8 VDC. I won't buy any rigs that can not run directly on this voltage. I see some late model HT's that can not run on 13.8 VDC such as the ICOM D-Star HT's and I won't buy that kind of equipment anymore. 73, Rick, KV9U James Wilson wrote: >Is there a noise free 12 volt to lower volt circuit that can be built? Maybe >one that would handle 9,5,3 and 1.5 volts. I would be willing to build cords >to remove all ac/dc converters from my radio area. > >
