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Title: Convert (invert) a pulse Post by: firewalker on November 07, 2007, 10:48:34 22:48 I have the following logic:
When a switch is not pressed the output is 24 volts. When the switch is pressed the voltage is 0. It is the output of a motor sending this pulse on every cycle. It sends continuously 24 volts and a 0 pulse when it completes a cycle. I want to invert this Logic. I want 0 volts and a 24 volts pulse on every cycle of the motor. I started to design a circuit with a transistor but I am stubbed for the moment… The circuit should be fast enough to “read” frequencies up to 50 kHz. Title: Re: Convert (invert) a pulse Post by: nacho1 on November 08, 2007, 01:51:00 01:51 if You want to drive a relay this schematic might help you:
http://www.wam.umd.edu/~toh/ElectroSim/Relay.GIF if you only want to have an inverted signal, then this are the calcs: condition to saturate the transistor ic>>ib, do ic>=10 x ib. so: rc = Vcc-Vce(sat) --------------------------- ic rb = VCC-Vbe --------- ib so choose your Ic, calc rc, then ib=ic/10 and then calc rb whis is an example with 5v & 12v for vcc http://www.mayothi.com/images/transistor3.gif you shuld take the signal from the colector I hope it helps greetings Title: Re: Convert (invert) a pulse Post by: ppa88 on November 08, 2007, 10:15:21 10:15 Here is a simple proteus simulation to illustrate it.
http://rapidshare.com/files/68256398/invert.rar.html Title: Re: Convert (invert) a pulse Post by: pl4tonas on November 08, 2007, 10:49:16 10:49 I suggest to use the transistor circuit proposed by the posts above but with an extra resistor connected between base-emmiter.
This should have a value between 2K2 to 10K (recomment the 2K2 or 3K3 value) and is used to ensure that any voltages near 0v i.e. 0.5 or 1V, would be treated as 0 level. |