hi
im hoping to build this http://www.slottechforum.com/slotin...ltage Comparators/LM339/LM339 oscillators.pdf bottom left
unfortunately ive met my nemesis- math/s.

r12 and c1 what units to use?
1/f intermediate frequency or more likely 1/f ?
>> much more than?


if i assume say r12 =25k=25000 ohms
" " c1 = 1n =.000001 farads
= .025
1/.025 =40 hz - when i should be looking for a few thousand hz on these figures, according to a similar example.

the xtal is 2 MHZ, i'm using a high speed comparator.

hope someone can help

doug

 

R is in Ohms, C is in Farads, 1uF is 0.000001, 1nF is 0.000000001, 1pF is 0.000000000001. , work backwards so 1/F = RxC

So your values R 25k x 1nF=0.00025Sec =40Khz

2Mhz is a 10K resistor and 50pF cap.

 

thanks DODGYDAVE youve saved my life,i'm glad you did it with zeros rather than powers of ten, which i never could get my head round,after all its easy to cancel most of the zeros.
thanks again,
doug

 

the powers of ten tell you how many zeros to cancel or add. 10 to the 6th, 1 with 6 zeros. one millionth, 1 times 10 to the -6, put the 1 in the sixth place to the right of the decimal point.

 

Errr...

1 times 10 to the -6 (minus 6), you would put the 1 in the 6th place to the right of the decimal point.