| 摘要 |
PURPOSE:To make it possible to economize many parts and mounting space by switching a constant current electronically in a wide range by a simple circuit constitution. CONSTITUTION:Timing resistances R1 to R8 are connected to the collector of switching transistors TrQ11 to Q18, and the other end is connected to constant current driving TrQ51. When any of terminals P11 to P18 is made high-level, any of TrQ11 to Q18 becomes conductive to flow a current to one of resistances R1 to R8. This current is made into a constant current by TrQ51 and is flowed to resistance R52, and a voltage is generated at both ends. The same voltage as this voltage appears in R51 having the same resistance value as resistance R52 and passes through constant current driving TrQ1 and is flowed to one of timing capacitors C1 to C8 which is connected to one of TrQ21 to Q28 turned on by the input given to terminals P21 to P28. As a result, the constant current according to resistances R1 to R8 can be flowed to TrQ1 by a current mirror circuit constituted by operational amplifier A1 and TrQ1. |
