bussard rotation ramp up

belkin321 · Post by **belkin321** » Tue Aug 19, 2008 2:47 am

Greetings,
How could an led bussard rotation circuit be modified to slowly ramp the rotation speed up, once power is applied? The bussard would then rotate at the speed defined by the circuit design. Thank you.

Pat Amaral · Post by **Pat Amaral** » Tue Aug 19, 2008 2:25 pm

I would think that could be accomplished by using a progammable microcontroller such as a PIC. I don't pretend to even have an idea of how to pull it off. I've only dabled. But there's a bunch of people here who use them on a regular basis.

tetsujin · Post by **tetsujin** » Tue Aug 19, 2008 3:02 pm

Pat Amaral wrote:I would think that could be accomplished by using a progammable microcontroller such as a PIC. I don't pretend to even have an idea of how to pull it off. I've only dabled. But there's a bunch of people here who use them on a regular basis.

Basically depends on how you handle the timing in your program - I usually just write delay-loops, so ramping up the speed could be done by gradually lowering the number of steps used for each delay...

If it's just a chaser circuit - I don't know precisely how you'd do it (I don't know the precise details of how to change the speed of a timer circuit like the 555, offhand) but it'd probably be a fairly simple matter to have a resistor-capacitor circuit that slowly charges up after power is applied (and drains once power is disconnected) and have the voltage over the capacitor affect the timer rate...

belkin321 · Post by **belkin321** » Tue Aug 19, 2008 11:33 pm

Thanks Pat and Tetsujin. Tetsujin, where in a chaser circuit would the resistor and capacitor be placed. Thanks again for any help.

tetsujin · Post by **tetsujin** » Wed Aug 20, 2008 4:19 pm

belkin321 wrote:Thanks Pat and Tetsujin. Tetsujin, where in a chaser circuit would the resistor and capacitor be placed. Thanks again for any help.

That's the part I don't know. :D I'm really a lot better with programs than I am with analog circuits...

jwrjr · Post by **jwrjr** » Wed Aug 20, 2008 10:20 pm

I use single-chip-computers by strong preference. With them, ramping up (or down) is pretty easy.

en'til Zog · Post by **en'til Zog** » Thu Aug 21, 2008 1:05 pm

You could try putting a capacitor around the main timing resistor of a 555 timer chip and see if that produces a ramped start and stop. Solderless experimenter's boards are great for that kind of experimentation.

You might try different values, of course, to see what they do. Anything from 1 uF to 330 uF would be where I'd start.

HTH

belkin321 · Post by **belkin321** » Thu Aug 28, 2008 2:03 am

Thanks to all for your assistance.

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