On 26/04/14 06:37, Uncle Peter wrote:
On Fri, 25 Apr 2014 10:57:47 +0100, Daniel
wrote:

Snip

Now, reduce the resistance to, say, 30 ohms to try to draw more current
from the supply (from Ohm's Law I = V/R so 12V/30 gives 0.4A. Does this
happen??

18 ohms, 8.55 volts. 0.475Amps
27 ohms, 12.45 volts. 0.4611Amps
36 ohms, 12 volts. 0.333Amps
47 ohms, 10.8 volts. 0.2298Amps
56 ohms, 10.7 volts. 0.191Amps
Open circuit, 12.73 volts. 0.000Amps

Not very "Constant Current"ish!! Mind you, not very "Constant Voltage",
either!!

I'd just guess a poorly regulated Voltage, Power Supply.

Daniel