Title:
DIRECT CURRENT POLARITY SWITCHING CIRCUIT
Document Type and Number:
Japanese Patent JPS5897957
Kind Code:
A
Abstract:
PURPOSE: To use the titled circuit for the calling device system of an exchange, by controlling turn on and off of a PNPN transistor (TR) from external.
CONSTITUTION: A PNP TR9 and an NPN TR10 constitute a PNPN switch. When "1" is inputted to a terminal 41, TRs 38, 15 and 24 turn on to absorb a constant current from the base of the TR9. Therefore, the PNPN switch turns on. When "0" is inputted to the terminal 41, TRs for driving the PNPN switch turn off. The input level is inverted by a gate 39 and a TR36 turns on. Then, the constant current flows to the base of an NPN TR25, which turns on. The NPN TR10 is cut off and the PNPN switch is turned off.
Inventors:
YOSHINO HARUYUKI
HASEGAWA KENZOU
INABE YASUNOBU
UEHARA HIROYASU
MUKAI KANJI
OKUHARA SHINJI
HASEGAWA KENZOU
INABE YASUNOBU
UEHARA HIROYASU
MUKAI KANJI
OKUHARA SHINJI
Application Number:
JP19706981A
Publication Date:
June 10, 1983
Filing Date:
December 08, 1981
Export Citation:
Assignee:
FUJITSU LTD
NIPPON TELEGRAPH & TELEPHONE
OKI ELECTRIC IND CO LTD
NIPPON ELECTRIC CO
HITACHI LTD
NIPPON TELEGRAPH & TELEPHONE
OKI ELECTRIC IND CO LTD
NIPPON ELECTRIC CO
HITACHI LTD
International Classes:
H04Q3/42; H03K17/73; H03K17/732; H04M19/00; H04Q1/38; (IPC1-7): H04M19/00; H04Q3/42
Attorney, Agent or Firm:
Sadaichi Igita
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