LY-1型晶体音响器/电铃计数器

用 途：是配各种（转子）流速仪测量转数用的听音计数.
电 源：直流电压3V（注意：请选用直径大小合适的两节5号电池）.
 
Power supply: DC3V
Application: It is an acoustic for various rotating current meter.