linear ramp generator

[shanky25]

i have given the output pulse train of an astable multivibrator to IC 555( operated in monostable mode)..My aim is to generate a linear ramp signal. I had connected a pnp transistor whose collector is given to pin6 which is further connected to pin 7.. then i connected it to ground with a capacitor of 22 micro in between.. now from the output pin 3.. i am getting a step output with very high delay time.. where did i go wrong?

 

[Roff]

i have given the output pulse train of an astable multivibrator to IC 555( operated in monostable mode)..My aim is to generate a linear ramp signal. I had connected a pnp transistor whose collector is given to pin6 which is further connected to pin 7.. then i connected it to ground with a capacitor of 22 micro in between.. now from the output pin 3.. i am getting a step output with very high delay time.. where did i go wrong?

Post a schematic, including all the parts connected to the PNP.
But be aware that the pin 3 output will always be a pulse waveform, with fast rise and fall times. The ramp will be on the capacitor.
Study the datasheet.

 

[Boncuk]

Try this circuit. It generates a ramp of 16 equal steps. Toggling SW1 the output wave form changes to something like a bowl. (sorry, don't know the exact term).

Use your NE555 for clocking. The duty cycle should be about 50%.

Hans

 

[Hero999]

You might as well use a PIC plus R2R converter if you want to do that.