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Modifying The Design?

I found a great circuit for a variable frequency strobe light at

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but I think it could be made a little bit better by replacing the 555 in the trigger oscillator with an XR2206 wave generator producing a square wave. The 2206 can be more easily frequency calibrated than the 555 but the pulse width from the

2206 is by it's very nature, fixed.

If I used the XR2206 would the fixed pulse width cause any problems?

Ron

-- "Everybody has a secret except for me and my monkey."

Reply to
Ron Hubbard
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bit

I am not at all sure that duty cycle is your only problem using the XR2206 as a replacement for the 555 in this circuit. The square wave output is specified for saturation voltage at only 2 mA, and I don't see an absolute maximum on the current from this pin.

But, I think you can get other duty cycles than 50% by replacing the single timing capacitor connected pin 5 to 6 with a pair of unequal capacitors connected between ground and 5 or 6. This trick works for the CMOS CD4067, but I can't unravel the schematic of this chip enough to tell if it will work as well, here. The other tack would be to have the FSK switch take place at each half cycle, switching timing resistors for the positive and negative half cycles.

But I don't see your problem with the 555, to begin with. It is pretty predictable. Do you want a calibrated speed dial on the timing resistor? I think that the typical adjustable resistor is less predictable than the 555.

Reply to
John Popelish

bit

It would be nice to replace the pot on the 555 with a rotary switch and individual resistors to get certain frequencies. With the XR 2206 the formula is simple and very accurate; I can't say that for timing resistors on the 555; it's usually more of pulling out the multi-meter and doing it by trial and error.

Ron

Reply to
Ron Hubbard

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