ผมสั่ง วงจรนี้มา 2ชุด แบบ high performance and Extend use มีภาคอัดไฟในตัว มีคำอธิบายด้วย ลองดูรายละเอียดได้ที่
http://www.amb.org/audio/mini3/ กำลังรอของที่เหลือจาก Digikey ครับ
Versatile power supply/battery charging circuit
* Both 7-cell ("8.4V") and 8-cell ("9.6V") rechargeable NiMH battery types are supported. A battery capacity of 230mAH or greater is recommended for long run times.
* A 7812 voltage regulator allows the use of an AC-to-DC adapter ("wallwart") that outputs anywhere between 15V DC to 24V DC (actual voltage) with a minimum current rating of 300mA for battery charging and for running the amplifier. Onboard voltage regulation allows a low cost unregulated linear AC-to-DC adapter to be used, while protecting the opamps from being damaged by over-voltage.
* The charging circuit, utilizing a LM317L voltage regulator wired as a constant current source, safely charges the battery at 16mA without risk of damage. A depleted battery can be charged back to capacity overnight.
* A zener diode protects the amplifier from damage if the battery becomes disconnected while the AC-to-DC adapter is plugged in.
* A power-on indicator LED is on the front panel, and a battery charging LED is on the rear panel.
* Ni-Cd batteries are not recommended due to the poorer charge capacity and memory effect. Li-Po, Li-Ion, or any non-rechargeable battery should not be used to avoid an explosion hazard.
* Two 470µF reservoir capacitors (for a total of 940µF) provide ample charge to feed the current demands from the amplifier. These capacitors are before the power switch, so they are always charged as long as the battery is connected. This avoids a large surge current during power-on, preserving the integrity of the switch contacts. It also ensures that the opamps' supply rails turn on and off instantaneously, eliminating noise.
ตอนนี้มีเจ้าตัวนี้ใช้อยู่ครับ อัดไฟได้เสียงดีมากๆ แข็งแรง และราคาถูก ใช้ MAXIM MAX9724 amplifier chip ชาร์จด้วยถ่าน 3.7V Lithium-ion battery ราคารวมค่าส่ง 1680 บาทเองครับ ตามรูป
