stuee Posted November 13, 2004 Report Share Posted November 13, 2004 Ok this might be a stupid question but we all start somewhere.Im making a power supply for my car to power my uniden cb. details belowUniden UH040XR/UH042XR/UH044 handheld UHF CB radios 24/12 Volt Output voltage: 7.0 VDC Output current: 70mA ok, the unit only needs 70mA, i was going to use the lm2675 stepdown regulator. The question is, its 1A so will that make any difference. or will the CB only draw what it needs ie 70mA.Its to run the internal battery charger for it.Another question is, i have a few things for the car i want to make a multi power supply for, Is there anything i can use that will go from roughly 1v to 24v and about 10A. my idea is to make a small box with a rotory switch on it, then put it to what i select. ie laptop, bettery charger, bla, blaThanks Quote Link to comment Share on other sites More sharing options...
ante Posted November 13, 2004 Report Share Posted November 13, 2004 Stuee,As long as the voltage is correct and the available current is higher than what you need it Quote Link to comment Share on other sites More sharing options...
audioguru Posted November 13, 2004 Report Share Posted November 13, 2004 Hi Stuee,If the radio has charging circuitry built-in, it will draw only what it needs, 70mA. But the current could triple or more if the radio is in operation while charging its battery.You don't need an expensive, complicated switching regulator for only 70mA. An inexpensive LM317T linear adjustable regulator will work fine from a car battery and won't even need a heatsink, unless you operate the radio while charging.You must make certain if your radios have charging circuitry built-in. Usually that circuitry is in the charger. If you connect 7V directly to the radio's battery, it might blow-up! If the battery is Lithium, it might catch fire!To get 1V to 24V at 10A from a car battery, you need a complicated and expensive buck-boost switching converter circuit. Quote Link to comment Share on other sites More sharing options...
ante Posted November 13, 2004 Report Share Posted November 13, 2004 Stuee, Audioguru,Many handhelds both scanners and two way radios have there charger circuit built in but some of them also have different input connectors for power and charge. There is another inexpensive regulator the LM7807 that should be considered here as an alternative. Quote Link to comment Share on other sites More sharing options...
audioguru Posted November 13, 2004 Report Share Posted November 13, 2004 Yes Ante,I agree that separate chargers are best. Murphy's Law says, Ka-boom, oops the switch was in the wrong position!7807? I've read about them, never seen one. [move];D ;D ;D[/move]My first happy face had too much to drink. Quote Link to comment Share on other sites More sharing options...
ante Posted November 13, 2004 Report Share Posted November 13, 2004 Hi Audioguru,There is not always a switch just two sockets on the side of the apparatus, it all comes down to the human factor here. 8) So, you are looking down the barrel of a bottle today? Well I hope your face is still happy anyway. ;D ;D Since you haven't seen any, I can tell you the 7807 looks just like the rest of the family. ;D ;D Quote Link to comment Share on other sites More sharing options...
login
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.