That would be anywhere from 100hz to 1.25Khz. The output frequency is going to be varied by a pot but the falling edge should be constant ~545uS +/-125uS long.hi 48,
What are the details of frequency and fall times you have in mind.?
Need a little more information, but it does sound feasible.
E
hi,Is there a simple way to adjust fall time of a simple ne555 square wave oscillator? Preferably with a pot.
The pot was for fine adjustment.hi,
You said in your opening post that the falling edge would adjusted by using pot. but now you say it should be constant at ~545uS +/-125uS long.
If an exponential fall time was acceptable, you could use a diode on the 555 output that charges a capacitor, which is discharged by a parallel resistor.
E
Need it to slope from max to base line.hi,
Linear could be done by using a Constant Current discharge of the cap.?
Do you want the slope to be from Vmax to 0V.?
E
Its only 2n3904 in SMT but was a constant current source what you meant by linear falling edge?OK, please post a datasheet for MMBT3904 and I can look thru it.
What load (resistance, capacitance, inductance) must Vout drive while maintaining the rise/fall times you spec? For example, in your schematic, Vout will fall more slowly as the load capacitance rises.There is no distortion on the output. Is it just a spice artifact?
@AudioguruThe 100 ohms input resistor quickly charges the 220nF capacitor but the 7mA current source slowly discharges it producing a falling ramp voltage.