Hello, gentlemen! I would appreciate, if someone could advice, what is wrong with my diy relay driver. I built it according to this scheme: http://www.cutting.lv/fileadmin/user_upload/bd140_scheme.gif
Relay is PE014005: http://www.te.com/catalog/pn/en/1393219-3 The transistor is BD140-16 http://www.datasheetcatalog.org/datasheet/stmicroelectronics/4186.pdf The diode is 1n4007 R1 is 220 ohm. M is output pin on Mesa card, set for current sinking. Base current should be 22mA, minimum HFE should be slightly below 40, so current on collector should be several hundreds of mA, while the datasheet says that relay coil is rated at 200mW, so it needs 40 mA. Output pin on Mesa card is working - it swings from +5,07 VDC to 0,60 VDC as I switch it on and off. But it seems that the transistor is not working - the voltage on collector does not rise above 0,00 VDC regardless of the state of Mesa output pin. I have tried: 1) shortcircuit base of transistor to GND (disconnected from Mesa card): relay not clicking; 2) shortcircuit collector of transistor to +5V: relay is clicking; So I know that relay is ok, but there is something about the transistor. I have exchanged 3 transistors already without any luck. What could I be missing here? Thanks in advance! Viesturs ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
