Hello People, I Have A Small Dc Power Supply That Is Rated At 6 vdc and 600 ma. I Am Using It To Power My 1980 Old Toshiba Am/fm/ Rec/play Cassette Recorder, Using The Auxillary 6 vdc Jack. What I Need To Know Is What SIZE Resistor [ in Ohms ] Do I Need In Series To Drop 2 volts; To Power My Sony Cd/mp3 Player Which Also Has An External Power Jack Rated At 4 vdc. This second power lead, runs off the 6 vdc lead in parallel. The CURRENT requirement For the Cd/mp3 Player is apx. 250 ma / 300 ma. However, It's Not Indicated In The Specs. I Don't Believe This Requires Building A Voltage Divider. Again, I only need a 2 VOLT DROP, and I am good to go here.
Thank's All For Your Help. Jim

HELLO-ALL, I FOUND A WEB SITE [ www.play-hookey.com ] THAT SOLVED MY DELIMMA. AS I SUSPECTED, I DON'T NEED A VOLTAGE DIVIDER. JUST, A SINGLE RESISTOR IN SERIES TO DROP THE VOLTAGE 2 VOLTS. TO THE 77 PEOPLE, WHO READ MAY POST TRYING TO SOLVE THE PROBLEM, CHECK-OUT THE WEB SITE ABOVE ! THANKS AGAIN FOR TRYING TO HELP, SINCERELY, JIM

Thanks for the update and link.

I think the single resistor solution will only work if you have a constant current draw. But a cassette recorder / radio will draw different amounts of current depending on what you're doing--playing tape, rewinding, radio, etc.

Not that it seems to matter anymore, but I would have suggested 3 diodes, serial, that would be a 2.1 V drop, no matter the current. I would use 1N4007, for up to 1 A.

Greets

Tom

Hello GhostKnight, and others:
I have a new, and different problem to tackle with my auto jump starter charging system. I have used it very little in the past 6 yrs, and most reciently it won't re-charge the battery before shutting itself off. This auto-shut off is similiar to a "Float charger system." Where it turns on when low, and shuts off when charged, and then just keeps repeating the cycle over, and over again.
The Problem with it, Is that before the battery is Fully charged it shuts off premature, and the cycle don't repeat, resulting in a very low battery. I am in the yellow/caution area when the charger turns off ... NO Good !
What I need to know is the Function process of the charger, and/or what senses the battery voltage, and when to turn it off ? I believe they all work on the same principle. Thanks-To-All, for your help. Nitrojc.