Originally Posted by herk7769
Diodes will drop voltage even for DC (wired forward bias).
Reaching into the "Way Back" machine I believe it is .5 volts drop per diode. You could wire several in series to get the DC voltage drop you need without hardly any heat generated.
OR you could just buy a voltage regulator solid state device for 5 volts and plunk it into the circuit. 5 Volt 5V DC Voltage Regulator 1 Amp L7805CV 7805 | eBay
Just a buck each.
Someone more "current" on solid state devices should chime in here.
Those voltage regulators are available in several different
voltages, including the 6v ( 1/2 12vdc) model. Like the 7806
for example. Available in several cases depending on power
dissipation required. TO-220, TO-3, etc.... I "think" that I
remember the 7806 is available in 2.2amp version as well
as lower current versions.
[Remember to use the HIGHEST "12v" your system produces
when calculating power dissipation in the regulator!]
As you say, you can probably find 'em on ebay. If not, places
like mouser.com, digikey.com, allied.com and other electronic
parts suppliers will have them. Three pin, fixed voltage regulators
are ...old... technology and available in surplus electronic stores
PS remember that when using diodes in the supply side (+), they
do *NOT* regulate voltage, only "drop" it. So as your 12v
supply goes up and down, the voltage to the load will