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Altering little schem

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bowser22

Member
Hi guys id like to alter this circuit to allow flashing in the range of 8 to 16hz.

the circuit currently only allows flashing of 1 to 5hz. what parts can i swap out to give me the rate i desire?
Thanks!
 

bowser22

Member
i alread purchased a kit for the circuit above though and was wondering before i put it togewther what i could alter
 

audioguru

Well-Known Member
Most Helpful Member
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.
 

BrownOut

Banned
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.
 

BrownOut

Banned
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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bowser22

Member
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
 

BrownOut

Banned
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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bowser22

Member
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.
 

Mr RB

Well-Known Member
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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