Soft start on a 555 timer

[MrHeckles]

Can a soft-start being implemented on a 555 timer through the control voltage pin (number 5).

What I am after is to start the 555 up at a low frequency and have it ramp up to a higher frequency slowly.

This is what I have in mind so far



My question is  - will this circuit addition mean that the boost converter slowly ramps up (due to the slowed frequency increase) or do I need another method?

[audioguru]

Hi Mr. Heckles,
Your transistor doesn't have base current so it won't do anything.
Sorry, but I think your idea is backwards. If you look on the datasheet for the 555, its frequency increases when the voltage at its pin5 control pin is low. You might be able to do it with a PNP transistor as long as you provide base current to it at 1st then let the base current decrease to allow the frequency to rise to normal. ;D

[Anotherforummember]

Inductors consume more current at low frequency that at high frequency.  This idea is better termed "hard turn-on"  Noise is what triggers SCRs.  monitor noise with o-scope.  Add ferrite beads here and there.  Use better swithces than voltage consumming mosfets, and use short wire lengths.

Stick to the source.  He knows what I mean.

[Guest Alun]

The duty cylce also gets lower too, which is what I think you're trying to achieve, what time constant6 are you after, you could do this by connecting a capacitor and resistor up to the control voltage pin.

[natasha]

SALAM
h r u?
i'm the new member n i don't know exactly how can i make the 555 timer so plz help me and send me full instruction means how i can make this and how it can work ok thanx