Measure the base voltage in the two states relative to +5 Dave Caroline
On Fri, Apr 20, 2012 at 4:18 PM, Viesturs Lācis <[email protected]> wrote: > 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 ------------------------------------------------------------------------------ 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
