# When I run the schemetic in LTSPICE,waves don't change direction.Why aren't waves changing direction here?

What pulse should I set to produce a waveform like in the graph?

u can always try something like this:

PWL(0 0 1.0000ms 5V 1.0001ms 0V 2ms -5V 2.0001ms 0)

basically 0.0001ms rise and fall time

Break the shape into simpler more realizable sub shapes. Apply the simpler sub shape to a generator. Apply the 2nd sub shape to a 2nd generator. Connect generators in series.

• By generators you mean voltages?
– ema
Mar 22, 2015 at 15:04
• Can you tell me the values in ltspice to insert?
– ema
Mar 22, 2015 at 15:36
• Not off the top of my head but one generator (yes, voltage) starts at t=0 and has a rising pulse voltage up to t1 then returns to zero at t1 until t2. The second generator is zero until t1 then has a negative rising pulse voltage until it reaches t2 then returns to zero. Mar 22, 2015 at 16:19
• But doing this only add the voltage
– ema
Mar 22, 2015 at 17:21
• Yes, the voltages add but at different points in time thus you can produce a complex waveform from several voltage sources; each source has its own time slot contributing to the final waveform. Mar 22, 2015 at 18:27