Multi AC adapter -Enoki

Multi AC adapter

The right photo shows AD-8723D of DC powr suppy. I was surprised at the price. The price of the specifications was twice or three times a few yeas ago.

Method ; dropper
Variable voltage ; 0 to 30V
Variable current ; 0 to 1.5A
Dimensions ; 95(W)x150(H)x235(D) mm
Mass ; 3.5kg
Price ; ¥13,000

Tbl.1 Ripple
Nominal	Average	ΔV/V
3V	3.3-3.4V	13%
4.5V	4.89V	6.5%
6V	6.58V	9.7%
7.5V	8.14V	8.9%
9V	9.49V	5.4%
12V	12.1V	1.1%

I will adopt cheaper a multi AC adapter with the charger board using IC723. The specifications of EAC-2000 are,

Method ; switching
Output ; 3/4.5V(2A), 6/7.5V(1.5A), 9/12V(1A)
Plug attachment ; 5.5, 5, 4.75, 4, 3.5, 2.4 mmOD
Dimensions ; 86x56x33 mm

I have 6V batteries. I designed charging two batteries by series. But the dissipation was very big because of 24VDC power supply. EAC-2000 is enought to charge the batteries, though switching supply is much noisy than dropper. I examined fluctuation or ripple of the output of EAC-2000 with no load by DSO.