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Altering little schem

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bowser22

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Hi guys id like to alter this circuit to allow flashing in the range of 8 to 16hz.
**broken link removed**
the circuit currently only allows flashing of 1 to 5hz. what parts can i swap out to give me the rate i desire?
Thanks!
 
i alread purchased a kit for the circuit above though and was wondering before i put it togewther what i could alter
 
C3 is 47uF. If you change it to 10uf then the frequency will be from 4.7Hz to 23.5Hz.
These capacitors are electrolytic so their tolerance is wide.
 
You don't need PR2, D2, or D3 if you only want to change frequency. Those are for duty cycle adjustment, and this scheme doesn't work well anyway.
 
It's not a good design. The % of duty cycle that is adjustable changes with the frequency adjustment. Believe me, I tried this same scheme on my bench. It sucks.
 
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ahhh i found that confusing as to the duration of the flashes coupled with the frequency, one variable has to be dependant on the other. what is a good circuit that i can get a kit for?
Thanks
 
There have been a couple ideas posted on how to do this. Attached is my idea. It works in simulation, but I haven't tried building it yet. Have other projects on my bench right now. R10/R13 are intended to model the variable resistor used for duty-cycle adjustment. R9 is for frequency adjustment.
 

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i now realise a xenon tube would be the way to go. i need a ready to build kit that will take 12v say from a car battery and flash a xenon at 14hz.
 
Just change C3 from 47uF to 10uF. The the 0-5Hz goes to 0-25Hz or so.
That should give you plenty of adjustment to illegally operate traffic lights by pretending to be an emergency vehicle. ;)
 
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