| The
very essence of Amateur Radio is building and testing your own
equipment. You don't have to be a rocket scientist to build your own
equipment. Many publications are devoted to do it yourself projects. The
American Radio Relay League publishes
many books and magazines devoted to the hobby.
|
 |
Laptop on board, when the 12 Volt battery is just not enough
My laptop
on board just does not work on the 12 Volt supply from the batteries. To solve
this problem I needed to make a DC-to-DC converter (shown on the right) that
could generate 15 - 18 Volts DC with a current of about 2 - 3 Amps.
As a solution I used an LT-1070 from Linear Technology, which can have a peak, switch current of 5 Amps and the maximum voltage supplied can be as high as 40 Volts. For most Notebooks this will be sufficient. (My IBM Thinkpad 600 draws about 1.8 amps at 16 Volts) The efficiency of the circuit is high; with no load the current is neglect able. (only 6mA quiescent current)
When in operation (at about 1.8 Amps constant) the LT-1070 becomes only hand warm. I have for security reasons made a small alominium plate to cool the LT-1070. The Diode D1 should be a fast trurn-off diode. Schottky diodes are best in this regard and offer better efficiency in the forward mode. Even when the supply battery power drops to about 5 Volts, the converter still operates perfect (not pleasant for the batteries and should be avoided). The circuit should be fused with a fuse of about 5 Amps (Slow blow)
Information on the LT1070 can be found here
Click here for another dc boost converter project. pdf file